Designing of Cranes With Standards

7/27/2019 Designing of Cranes With Standards

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A list of Indian Standards relevant to this standard is given in Annex F.This standard is the first in the series of standards relating to cranes and covers the

structural design. The other standards in the series covering the mechanical and electrical

portion are as follows:

IS 3177:1999 Code of practice for of overload traveling cranes and gantry cranes other

than steel work cranes ( Second Revision)

IS 807 : 2006 Design, Erection and testing (Structural Portion) of Cranes and Hoists -

Code of Practice

The committee kept in view the manufacturing and trade practices prevailing in the

country while formulating the standard. Assistance has also been derived from the

following publications:

For the purpose of deciding whether a particular requirements of this standard is

complied with the final value, observed or calculated expressing the result of a test oranalysis, shall be rounded off in accordance with IS 2:1960 Rules for rounding off

numerical values (revised). The number of significant places retained in the rounded off

value should be the same as that of the specified value in this standard.[In case of codeof practice, this clause will not be applicable.]


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CONTENTS

Section I - GENERALPage

1.1. SCOPE...091.1.1 TERMINOLOG......091.1.2 CAPACITYIDENTIFICATION.....091.1.3 INFORMATIONTOBESUPPLIEDWITHENQUIRYORORDER.10 1.1.4 WORKMANSHIP,MATERIALANDINSPECTION10 Section II MECHANICAL COMPONENTS2.1.0 CALCULATIONPROCEDURE.122.1.1 CHECKINGFORULTIMATESTRENGTH.122.1.2 VALUEOFTHEPERMISSIBLESTRESS..122.1.3 VALUEOFTHECOEFFICIENTVR..132.1.4 RELATIONSBETWEENTHECALCULATED

STRESSESANDTHEPERMISSIBLESTRESSES....13 2.1.5 CHECKINGFORFATIGUE....142.1.6 STRESSES...142.1.7 PERMISSIBLEFATIGUESTRESS...152.1.8 CHECKINGFORCRIPPLING....16 2.1.9 CHECKINGFORWEAR...16

2.1.10HOOKS...16 2.1.11ROPEDRUMS..192.1.12ROPES.202.1.13SHEAVES.21


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2.1.14EQUALIZERBARORSHEAVES232.1.15TRACKWHEELS23

2.1.16BUMPERS262.1.17SHAFTING.28 2.1.18PRESSFITSANDKEYS29 2.1.19BEARINGS.30 2.1.20GEARING..............312.1.21MACHININGSPECIFICATIONS....342.1.22GEARBOXES.34 2.1.23LUBRICATION....36 2.1.24LINESHAFTINGANDCOUPLINGS..372.1.25RAILS..38 2.1.26OPERATORSCABIN..38 2.1.27MEANSOFACCESS.40

2.1.28GUARDING..402.1.29WEATHERPROTECTION..402.1.30PAINTING412.1.31HANDLINGFACILITIES412.1.32BRIDGEANDTROLLEYDRIVES.41

2.1.33TORSIONALDEFLECTIONANDVIBRATION....432.1.34MOTIONLIMITINGDEVICE....432.1.35CROSSTRAVELANDLONGTRAVELLIMITINGDEVICES.44


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2.1.36LOADINDICATIONANDLOADLIMITINGDEVICES....442.1.37DRAWINGSANDDOCUMENTS...44 Section III ELECTRICAL EQUIPMENT3.0ELECTRICALEQUIPMENT...453.1POWERSUPPLY453.1.1GENERAL...453.1.2DSLSYSTEMSANDACCESSORIESFORCRANES463.1.2.1GENERAL....463.1.2.2CONDUCTORS..463.1.2.3CURRENTCOLLECTORS.463.1.3CROSSTRAVELCURRENTCOLLECTINGSYSTEM..473.1.3.1GENERAL..473.1.3.2CONDUCTORS....473.1.3.3COLLECTORASSEMBLY....47

3.1.4EARTHING....473.1.4.1GENERAL47 3.1.4.2CONTROLCIRCUITEARTHING...483.1.4.3MAGNETEARTHING..483.1.5CONDUCTORBARS,CABLEREELSANDFLEXIBLECABLES.483.1.6CALCULATIONOFCROSS-SECTIONOFCONDUCTORS..50

3.1.6.1GENERALOPERATINGCONDITIONS...503.1.6.2INTERMITTENTDUTYAPPLICATIONS.50 3.1.6.3CO-ORDINATIONBETWEENCONDUCTORSANDPROTECTIVE


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DEVICES....50

3.1.6.4SHORTCIRCUITPROTECTIONOFCONDUCTORS..513.1.6.5CALCULATIONOFTHECROSS-SECTIONINRELATIONTOTHE

ADMISSIBLEVOLTAGEDROP.....523.1.6.6CALCULATIONOFTHEMINIMUMCROSS-SECTIONINRELATION

TOTHETHERMALCAPACITYOFTHECONDUCTORS..56

3.1.6.7INSTALLATIONOFCABLES....573.2ELECTRICALPROTECTIVEANDSAFETYEQUIPMENT.593.2.1PROTECTIVEEQUIPMENT..593.2.1.1GENERAL.....593.2.1.2ELECTRICALPROTECTIVEDEVICE....623.2.1.2.1GENERAL..623.2.1.2.2PROTECTIVEDEVICECOMMONTOALLMOTIONS..633.2.1.2.3SCHEMEAPROTECTIVEDEVICEFOR

INDIVIDUALMOTIONS..64

3.2.1.2.4ACINSTANTANEOUSRELEASESINGLEPOLEOVERLOAD64

PROTECTIVEDEVICEFORINDIVIDUALMOTIONS:..

3.2.1.3PROTECTIVEDEVICESFORMOTORCIRCUITS.653.2.1.4CONTACTORS..663.2.1.5CONTROLSWITCHFUSE..663.2.1.6EMERGENCYSWITCHES..66

3.2.1.7OFF-POSITIONINTERLOCKING....673.2.1.8PILOTLAMP..673.2.1.9MAINFEATUREOFBUILT-INCRANEWEIGHINGSYSTEM

(LOADCELL)..67

3.2.1.10AUXILIARYISOLATINGSWITCHESANDFUSES...68


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B)MOVINGCABCRANES.693.2.1.11DISTRIBUTIONBOARD..70

3.2.1.12AUXILIARYSWITCHESOTHERTHANISOLATIONSWITCHES..713.2.1.13IDENTIFICATIONOFCIRCUITS.723.2.1.14DISPOSITIONANDHOUSINGOFELECTRICALEQUIPMENT..723.2.2SAFETYFEATURES....743.2.2.1MOTOROVERSPEEDPROTECTION..743.2.2.2DEVICESFORSWITCHINGOFFFORPREVENTIONOFUN-

EXPECTEDSTARTUP..74

3.2.2.3LIMITSWITCH..753.2.2.3.1LIMITSWITCHESINHOISTMOTION.753.2.2.3.2TRACKLIMITSWITCHES...763.2.2.3.3PROXIMITYSENSING/ANTI-COLLISIONDEVICES.763.2.2.4SAFEGUARDINGMOTORSAGAINSTOVERHEATING.77

3.2.2.5OVER-CURRENTPROTECTIONOFCONDUCTORS..783.2.2.6SAFEGUARDINGAGAINSTABSENCEOR

INVERSIONOFPHASES..78

3.2.2.7ACTIONOFSAFETYDEVICES793.2.2.8PROTECTIONAGAINSTTHEEFFECTSOFLIGHTNING..793.3DESIGNANDSELECTIONOFMOTORS...80

3.3.1GENERAL.....803.3.2SELECTIONOFMOTORSFORHOISTMOTION..833.3.3MOTORFORCRANETRAVELORTROLLEYTRAVERSE.863.3.3.1GENERAL......86


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3.3.3.2SELECTIONOFMOTORSFORCRANETRAVELOR

TROLLEYTRAVERSE....86

3.4DESIGNINGTHECRANECONTROLS...93

3.4.1CRANECONTROLLINGARRANGEMENTS933.4.1.1GENERAL....933.4.1.2CONTROLLERS..943.4.1.3CONTROLLERSPROVIDEDINTHECABIN953.4.1.4PENDANTCONTROLLERS...973.4.1.5REMOTECONTROL.....983.4.1.6RESISTORS...1023.4.1.6.1GENERAL..1023.4.1.6.2FITTINGS..1023.4.2CRANECONTROLS...1033.4.2.1THYRISTORCONTROLMAINFEATURES..103

3.4.2.2SPECIALPROTECTIONFORDIRECTCURRENTDRIVESYSTEM.105

3.4.2.3THYRISTORCONTROLLERSFORSLIPRINGMOTORS...1063.4.2.4VARIABLEFREQUENCYDRIVES....1073.4.2.4.1GENERAL.1073.4.2.4.2VFDSELECTION..108

3.4.2.4.3DYNAMICBRAKINGSELECTIONFORVFDS...1103.5BRAKING.1113.5.1ELECTROMECHANICALBRAKING...1113.5.1.1GENERAL....111


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3.5.1.2HOISTMOTION...1123.5.1.2.1GENERAL.112

3.5.1.2.2BRAKINGPATH..1123.5.1.3LONGTRAVELANDCROSSTRAVELMOTIONS.....1133.5.2ELECTRICALBRAKING....1142.5.3BRAKEMAGNETCOILS...114TABLEBRAKEMAGNETCOILRATINGS....114

TABLE2.BRAKEMAGNEETOPERATINGVOLTAGESANDCURRENTS.1153.6AUXILIARYELECTRICALEQUIPMENT.....1183.6.1LIGHTING....1183.6.1.1CABIN...1183.6.1.2WORKINGAREALIGHTING.....1183.6.1.3ACCESSANDMACHINERYLIGHTING....1193.6.1.4EMERGENCYLIGHTING....119

3.6.2HEATINGANDAIR-CONDITIONING.1193.6.2.1MACHINERYHOUSE...1193.6.2.2OPERATORCABIN..1193.6.3AUXILIARYCIRCUIT.1203.6.4LIFTINGMAGNETS&LOADHOLDINGDEVICES.120

3.6.4.1GENERAL.....1203.6.4.2MAGNET...1213.6.4.3MAGNETLEADANDCABLE1223.6.4.4MAGNETCOUPLINGS....122


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3.6.4.5CABLEDRUM..1223.6.4.6MAGNETCONTROLANDPROTECTIVEEQUIPMENT1233.6.4.7BATTERYBACKUPSYSTEM.....123

Section IV INSPECTION AND TESTING4.1.10CRANEINSPECTIONANDTESTING125 4.1.13INSPECTIONPROCEDURE..127 4.1.14GENERALREMARKS....130 4.1.34TESTING....133 APPENDIXA Listofsteelplantcranesandspecialservicemachine138B Informationtobesuppliedwiththeenquiryororder..139 C Selectionofmotors...147D RatingofResistors....150

E Preferredparameters....150 F ReferenceStandards....151


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DraftIndian Standard

Code of practice for heavy duty electric overhead travelling cranes including special

service machines for use in steel work (Second Revision of IS 4573)

SECTION I - GENERAL

1 SCOPE

1.1 This code covers design, manufacture and erection of heavy duty electric overhead traveling cranes for use in steel works. Its provisions where applicable, shall also

apply to special service machines, such as those listed in Annex A.

1.2 This crane service classification system applies specifically to fatigue strength

analysis of Mechanical components. The maximum rated load will also be used to checkthe crane for static strength, buckling, deflection and stability.

1.3 The concept of classification may also enter into the rating and selection of electrical

equipment and provide guidance for the selection of components which have a metal life

between replacement.

1.4 This code is not intended for application to cranes for use in areas where sparks from

cranes could lead to explosions. Which are covered IS 3177.

2 REFERENCES

The standards given in Annex A contain provisions, which through reference in this text,

constitute provisions of this standard. At the time of publication, the editions indicatedwere valid. All standards are subject to revision and parties to agreements based on this

standard are encouraged to investigate the possibility of applying the most recent editions

of the standards indicated at Annex G.

3 TERMINOLOGY

For the purpose of this standard the definitions given IS 13472 (Part 1)1992/ ISO 4306-1:2007 shall apply.

4 IDENTIFICATION

4.1 A small plaque shall be located in a prominent position in the cab bearing the

following inscription:

a) Manufacturers name;

b) Manufacturers serial number; and


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c) Year of manufacture

d) Capacity of each hoist shall be shown on each side of crane in such amanner as to be easily legible from the floor.

4.2 Information to be supplied with Enquiry or Order

Information regarding the conditions under which the crane is to be used, together with

the information required in Annex B, shall be supplied with the enquiry or order.

4.3 Information to be supplied by the Manufacturer

The manufacturer shall supply all tender documents including drawings giving the over

all sizes, clearance, end approaches, structural features, travel wheel loads, end carriagebuffers, impact forces, wheel spacing, etc.,

5 WORKMANSHIP, MATERIAL AND INSPECTION:

Workmanship and material shall be subject to the inspection of the owner or hisrepresentative at all times. Weldments of carbon steel (except bridge girders) shall be

stress relieved by uniformly heating in a furnace. Field welds shall likewise be stress

relieved unless other means agreeable to the owner as specified in the information sheet.The temperature of the furnace when the weldment is placed in it shall not be over 150C

at the start and increased to 650C at a rate not exceeding 95C/hour, and then held at thetemperature for 1 h/25mm of thickness of material. It shall then be cooled in the furnace

at a rate (not exceeding 95C/hour) to 260C, before being removed from the furnace.

Weldments of alloy material shall be welded and stress relieved using a procedurespecified by the owner.


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SECTION 2 MECHANICAL COMPONENTS

5. CALCULATION PROCEDURE5.1 Mechanism components shall be designed by checking that they offer required

safety against failure due to fracture, crippling, fatigue or excessive wear. Other

factors shall also be taken into consideration and it is particularly important toavoid over heating or deflection which may interfere with correct functioning of

the mechanism.

5.2 CHECKING FOR ULTIMATE STRENGTHMechanism components shall be checked for ultimate strength by verifying that the

calculated stress shall not exceed a permissible stress dependent on the braking

strength of the material used.

5.3 VALUE OF THE PERMISSIBLE STRESS

The value of the permissible stress a is given by the following formula:a = R/VR , Where:a is the ultimate stress of the material

VRis a safety coefficient corresponding to each case of loading.5.4 VALUE OF THE COEFFICIENT VR

The values to be adopted for VRare given in table I below:Table I

Case of lading IV exceptional loading condition

Value of VR 1.8

5.5 Relations between the calculated stresses and the permissible stresses.

According to the types of loading considered, the following relations shall be

verified in which:

t is the calculated tensile stressC is the calculated compressive stressfis the calculated bending stresss is the calculated Shear stress(a) Pure tension : 1.25 ta(b) Pure compression : c a

(c) Pure bending : f a

(d) Combined bending and tension: 1.25 t + f a(e) Combined bending and compression: c + f a(f) Pure Shear : 3 s a

(g) Combined tension, bending and shear:[(1.25 t + f)

2+ 3 s

2]

o.5 a

(h) Combined compression, bending and shear:[( c + f)

2+ 3 s

2]

o.5 a5.6 CHECKING FOR FATIGUE

General method -The fatigue strength of a given component is mainly determinedby the following factors

a) The material from which the component is constructed.


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b) The shape, surface condition, state of corrosion, size (scale effect) and

other factors producing stress concentration.c) The ratio between the minimum and maximum stresses which occur

during the various stress cycles.

d) The stress spectrum

e) The number of stress cycle5.7 STRESSESThe following characteristics shall be determined for each type of fluctuating stress,

tension, compression, bending or shear, occurring during an appropriate stress cyclein the component details having regard to the loading that it will experience.

max, min = extreme values of stress occurring in the stress cycle.

min = considered as negative if it is of opposite sense to maxPfb = permissible fatigue stress in bending

Pts = permissible fatigue stress in shear

Pfb = fatigue reference stress at which a component details has a 90 percentprobability of survival

omax, amin = extreme values of axial tensile stress.bmax, bmin = extreme values of stress in bending

smax, smin = extreme values of torsional shear stressmax, min = Max degree of stress fluctuation.

5.8PERMISSIBLE FATIGUE STRESSThe permissible fatigue stress Pfs for each type of stress, tension, bending or shearis given by:

Pfs = 0.8 Pfrfor hoisting mechanisms

= 0.85 Pfrfor all other mechanisms.Where the component detail is subjected to a single type of fluctuating stress, that is

max shall not exceed Pfthe permissible fatigue stress.The stress combination occurring most frequently in practce in a component detail

is that of bending and torsion. The details subjected to this combination shall be

designed so that( b Max )

2+ ( s Max )

2< 1.0

Pfb Pfs

5.9 CHECKING FOR CRIPPLINGComponent subjected to crippling that in overall flexural buckling due to axialcompression shall be checked so that the calculated stress does not exceed a limit

stress determined as a function of critical stress above which there is a risk of

crippling occurring. For this check co-efficient Cdf of IS 3177 (Table 2).

5.10 CHECKING FOR WEARIn the case of parts subjected to wear, the specific physical quantities such as

surface pressure or the circumferential velocity shall be determined.NOTE: Annex B of IS 3177shall be referred for calculating the fatigue stress Pfr.

5.11 HOOKS

5.11.1 Generally hooks shall be designed material clause as per IS 3664 for infinite life

based on the rated load except where the owner specifies finite life design. The designshall be established by analysis or testing.


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5.11.2 Hooks shall be forged from fine grain material. Any welding on the hook shall be

with the approval of a qualified welding engineer and performed prior to initial heattreatment. The capacity of the hook may be stamped on the hook nose. The hook shall

not be painted.

5.11.3 Hook shank

The calculated maximum stress at the root of the thread of the shank section,including a fatigue stress concentration factor for the type of thread used, shall not

exceed 0.33 of minimum ultimate tensile strength at mid-radium.

5.11.4 Considerations:Due consideration shall be given to impact, service and to the possibility of bending

forces on the hook shank. These bending forces will be partially dependent upon the

geometry of the hook saddle and the coefficient of friction between the hook saddleand the loading element.

The shank shall be undercut below the last threads for a length of at least two pitches

to allow for a uniform stress flow. The undercut shall have a radius at each change indiameter.

5.11.5 Hook BodyHook bodies shall be as per IS 3664 where the line of the resultant load on the hook

passes through the center of curvature of the inside edge of the hook and coincideswith the centreline of the shank. The lifting Hooks shall comply with IS 3815 and IS

5749. The maximum combined stress at the inner surface of curvature of the critical

section 90 degrees from the vertical load shall not exceed 0.33 time of minimumultimate strength. This applies to hook bodies of trapezoidal section. Where square

or rectangular sections are used, these stresses shall be reduced by at least 10 %.

5.11.6 TestingWhere hook capacity has been established by testing, the static load required to

straighten out the hook body shall not be less than 5.0 times the rated load.A certificate of compliance showing both fatigue and static load testing covering both

the configuration of the hook body and the hook shank shall be provided.

Approval by the owner shall be obtained for hooks selected on this basis.5.11.7 Sections

Proportions of hook sections other than the critical section shall be such that the stress

does not exceed the stress in the critical sections.

5.11.8 ThreadsThe hook nut and shank threads shall provide required strength for the hook capacity.

Due consideration shall be given to the weakening effect of the nut locking

arrangement.5.11.9 Latches

Hook latches and swivel lock plates shall be provided when specified.

5.11.10 Laminated Point hooksLaminated hooks shall be made for steel works and foundries for lifting and carrying

molten masses in spigot ladles. The material, dimensions, design, components and

assembly for laminated point hooks are covered IS 5749 and part and technicaldelivery conditions for laminated hooks are covered IS 5749.

5.12 ROPE DRUMS


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5.12.1 Drum shall be rolled or centrifugally cast steel as per IS 2328 Flanged ends, if

required, shall not be less than 2.5 mm in thickness and project not less than 65mm. beyond the pitch diameter of the drum.

5.12.2 Drums shall have wrapped grooves of a depth equal to 12 mm of the diameter of

the hoisting rope and a pitch of not less than 1.2 times this diameter. The groove

radius shall be 0.8 mm in. larger than the radius of the rope. Drums shall bedesigned so that not less than two complete wraps of hoisting rope will remain in

the grooves ahead of the first rope clamp when the hook is at the lowest position.

In addition, it shall be possible to lay the hook block on the floor for maintenancewith one full wrap remaining on the drum.

5.12.3 One empty groove for each rope shall be left on the hoist drum when the hook is

in the highest position. This provision is to insure that overlapping of the ropewill not occur when the hook is in the highest drifted position.The pitch diameter

of the drum for 6 x 36 wire rope shall not be less than 30 times the diameter of the

hoisting rope used for Classes M7 and M8 cranes.5.12.4 Radius of the bottom of the groove

The useful life of the rope depends not only on the dia of the pulleys and drums, butalso on the pressure exerted between the rope and the groove supporting the rope.

The winding ratios are given as the radius of supporting groover where r = 0.53 d, dbeing the nominal dia of the rope.The drum gear shall be keyed and pressed on to

the periphery of the hub or shell of the drum, or shall be bolted with fitted bolts to a

flange on the drum or by other attachment means as approved by the owner. Thelead angle of the rope shall not exceed 5

oon either side of helix angle of the groove

in the drum. The contour at the bottom of the grooves shall be circular over a

minimum angle of 120o.

5.13 ROPES5.13.1 The hoisting ropes shall be of the grade and type specified in IS 2266. Based on

the static breaking strength, a design factor of 8 shall be used for hot metal handling

hoists and 5 for hoists other than hot metal handling.The sheave arrangement should

be reeved so as to eliminate reverse bends except at the drum.5.13.2 The maximum allowable fleet angle for frequent working positions shall be 2

degrees for Classes M7 and M8 cranes. The maximum allowable fleet angle for

seldom reached positions shall be 3 degrees for Classes M7 and M8 cranes.When

special reeving, such as a stabilised reeving arrangement is used, consideration mustbe given to geometry and dynamics to maintain the appropriate safety factors.

Provisions should be made to prevent the twisting of the hook block.

5.13.3 Where load swinging can occur due to the crane service, rope lead angles shall beset, or other provisions made, to minimize or eliminate the possibility of the rope

skipping grooves on the hoist drums. When designing hoist drums the following

should be taken into consideration. On high duty cycle cranes, drum groovesshould be flame hardened to a minimum of 400 BHN.

5.13.4 The minimum breaking load Fo of the intended for a particular duty shall be

determined from the formula given below, however impact factor shall not beconsidered while calculating the rope tension

Fo = S x Zp x Cdf


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S Maximum rope tension considering inclination of the rope in the upper

most position.Zp Minimum practical co-efficient of utilisation. For M7 and M8 duty,

Zp shall be taken equal to 6.0

Cdf duty factor for hoisting as defined in 7.4.3 of 3177

5.14 SHEAVES5.14.1 The pitch diameter of all sheaves, except equalizer sheaves for 6 x 36 wire rope

shall not be less than 30 times the diameter of the hoisting rope used for Classes M7

and M8 cranes. Use the next larger size diameter for lead sheave. Sheaves shall beenclosed by guards which fit close to the flanges to prevent the ropes from coming

out of the groves. The material of the sheaves shall be as per IS 1030 Gr B

1989.The bearing assembly in each sheaves shall be individually lubricated. Thefittings and grease lines shall be located so that they will be protected from damage.

Where possible, upper sheave block mountings shall be above the trolley deck. The

upper sheaves block shall be removable as a unit from the above.5.14.2 Grooving

Sheaves shall have machined groove. The contour at the bottom of the grooveshall be circular over a minimum angle of 120o

and shall have an included angle

of 45o. The depth of the groove shall not be less than 1.5 times the dia of the

rope. The radius of the groove shall be between 0.53 to 0.59 times the dia of the

wire rope rounded of upwards to the nearest 0.5 mm on higher side.

5.14.3 Diameter of the SheaveThe diameter of the bottom of the groove at an equalizing sheave shall not be less

than 65 percent at the minimum sheave diameter. The value shall be calculated as

per clause 8.5.2 of 3177. The minimum winding diameter shall be calculated asper the formula, D H.d.Where:

D the winding dia meter on pulley or compensating pulleys

H a coefficient depending upon the mechanism group

d the nominal dia of the rope.The value of H for main pulley shall be 28

The value of H for compensating pulley shall be 18,

5.15 EQUALIZER BARS OR SHEAVES

5.15.1Where required, either an equalizer bar or sheave will be acceptable. In either casethe bar or sheaves shall be positioned to be accessible from the floor of the trolley and

made in such manner that it can turn or swivel to align itself with the pull of the

ropes. Equalizer sheaves shall have a pitch diameter not less than 18 times thediameter of the rope. Cranes having hoists which handle hot metal or critical loads

should utilize equalizer bars to provide two independent rope systems, not equalizer

sheaves. Forincreased rope life, consideration shall be given to using equalizer sheaves with

the same diameter as the running sheave.

5.16 TRACK WHEELS5.16.1 All track wheels shall be double flanged. The blanks shall be made by roll

forming, forging or casting from grades of steel appropriate to the forming

process. Bridge track wheels shall have either straight or tapered treads. The


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material of the wheels shall be grade C 55 Mn 75 of IS 1570(Pt I & II) Bridge

wheel loads shall be determined with the maximum lifted load on the trolley,which shall be positioned at the closest working approach that produces the

maximum wheel load. Trolley wheel loads shall be determined with the maximum

lifted loads,

Max lift load = (Wt+ WL + WA) , where:

5.16.2 Material for wheel

The material for the track wheel shall be grade C55 Mn 75 of IS: 1570 and alsomay be of steel. The steel shall not contain more than 0.06 percent either of

sulphur or phosphorus.

5.16.3 Dia of the wheelsThe Thread diameter of wheels shall be standardised to sizes 160, 200, 250, 315,

400, 500, 630, 710, 800, 900, 1000 and 1250 mm. The minimum tread diameter

of the wheel may be calculated from the formula given below:

W x Cdf x CsfD =1.5 a x Cbh x Csp

Where:D Tread dia of the wheel in mm

W Maximum wheel load in newtons

a useful width of railCdf duty factor undefined in 7.4.3 of IS 3177

Cbh hardness factor for the wheel. For values refer Table 9 of IS

3177Bhw as calculated in 7.4.3 of IS 3177

Csf safety factor depending on the material used as defined in7.4.3 of IS 3177Csp Co-efficient depending on the speed of rotation of the wheel

defined in Table 10 of IS 3177.

5.16.4 Determining the mean load

In order to determine the mean loads, the procedure is to consider the maximumand minimum loads with stood by the wheel in the loading cases considered, i.e.

with the crane in normal duty but omitting the dynamic factor. The values of P

mean shall be determined by the formula for loading case I and II, IIIP mean = (P min I, II, III + 2 P max I, II, III) / 3

5.16.5 Determining the wheel width

a) Flat bearing surface : a = B 2rb) Convex bearing surface : a = B 4r/3

where:

B width of the rail, and

R radius of the rounded corners of the side5.16.6 Flanges

The dimensions of flanges for guiding trade wheels at the base shall not be less

than the values given in Table 11 of IS 3177/1999.

WT- WeightofthetrolleyWLWeightoftheliftedloadWA-Weightofthecolums


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5.16.7 Determining the limiting pressure P1

Table

Values of PL

Ultimate strength for metal usedfor rail wheel

PL in N/mm2

500 N/mm

2

5.0600 N/mm

25.6

700 N/mm2

6.5

800 N/mm2

7.2

5.17 BUMPERS5.17.1 Provisions in the design of the runway and the design of the runway stops shall

consider the energy absorbing or storage device used in the crane bumper. The

device may be nonlinear (e.g hydraulic bumpers) or a linear device such as a coil

spring.

5.17.2 The maximum deceleration rate for both bridge and trolley shall not exceed 5 m/s2

at l50% of the full load rated speed (full load rated speed shall be used unlessadequate information is supplied by owner to determine the actual attainable

maximum speed.) Additionally, bumpers shall be capable of absorbing the totalenergy at 100% full load rated speed.

5.17.3 Between cranes or trolleys (if two trolleys are located on one bridge) bumpers

shall be capable of absorbing the energy from 70% of full load rated speed of bothcranes or trolleys travelling in opposite directions, or the energy from 100% of

full load rated speed of either crane or trolley, whichever is the greatest.

5.17.4 The design of all bumpers shall include safety cables to prevent parts fromdropping to the floor. For computing bridge bumper energy, the trolley shall be

placed in the end approach which will produce the maximum end reaction fromboth bridge and trolley. This end reaction shall be used as the maximum weight

portion of the crane that can act on each bridge bumper. The energy absorbing

capacity of the bumper shall be based on power-off and shall not include the liftedload if free to swing. Bridge bumpers shall have a contact surface of not less than

125 mm in diameter, be located on the rail centreline and mounted to provide

proper clearance when bumpers of two cranes come together and both are fullycompressed. Where practical, they shall be mounted to provide for easy removal

of bridge track wheels.

5.17.5 Buffers shall have sufficient energy absorbing capacity to bring the loaded cranes

or crab to rest from a speed 50 percent of the rated speed at a deceleration rate notexceeding 5 m/s2.

5.18 SHAFTING

5.18.1 Hoist shafting design torque shall be based on the torque required to lift the rated

load plus hook block and/or lifting beam and shall take account of mechanical

efficiencies. Design torque for all travel drives shall be based on 2 times the 60minute motor rating for series wound, constant potential D.C drives, and 1.7 times

the 60-minute motor rating for A.C motors and adjustable voltage D.C drives


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without motor field weakening, or wheel slip at maximum wheel load (0.20

friction factor) whichever is lower. Due consideration shall be given to themaximum brake torque which can be applied to the drive.

Axles or shafts which are provided with sleeve bearings are to be surface or case-

hardened and ground.

5.18.2 ShaftsAll shafts shall be made of low alloy steel of C 45 and axles shall have strength,

rigidity and required the bearing surfaces. All shafts shall be supported on

minimum two bearing. Angular deflection of the line shaft at torquecorresponding to 1.5 times the motor torque during the acceleration period shall

not be more than 0.25o

per meter of shaft length. The drive for line shaft shall be

mounted as close as practicable to the centre of the span.5.18.3 Stress calculations - All shafting shall be designed to meet the stresses encounted

in actual operation. Due consideration shall be given to the maximum Torque which

may be applied to the shaft. When significant stresses are produced by the otherforces, these forces shall be postioned to provide the maximum stresses at the section

under consideration. Impact shall not be included.5.18.4 Fatigue stress check for normal operating conditions - Any shafting subjected to

fluctuating stresses such as the bending or rotating shafts or the torsion inreversing drives must be checked for fatigue. The bearing stress must not exceed

50% of the minimum yield strength for non - rotating shafting.

5.19 PRESS FITS AND KEYS5.19.1 Keys shall be provided for all connections subject to torsion. All gears, pinions

and couplings shall be pressed or shrunk onto shafts in addition to being keyed.

All press fits shall be made in accordance with IS: 2048/1983 Preferred Limitsand Fits for Cylindrical Parts. All keys and keyways shall be radiused and/or

chamfered according relevant Indian Standard.

5.20 BEARINGS

5.20.1 Antifriction bearings shall be spherical, tapered, straight. Antifriction bearings

shall be selected on the basis of B-10 life, to give a minimum life expectancy often years or 5,000 to 40,000 hours under the service conditions for which the crane is

intended. Bearing selection in this specification is based on the total number of

cycles which it is expected the bearing will undergo during the number of hours

service the crane will be used in a 10 year period.5.20.2 All bearings selected shall meet the required life at 75% of the maximum bearing

load (at rated speed) based on the recent catalogue rating of the bearing

manufacturer. Bearings are selected for 75% of the maximum load (at ratedspeed) on the assumption that this gives a practical average value for fatigue life

purposes. If the load on the bearing is essentially constant, the bearings must

meet a required life of 100% of the maximum load at rated speed. In some casesaxle sizes establish bearing sizes.With wheel bearings of the antifriction type, one

bearing on each wheel axle shall be of the fixed type. The other bearing shall be

arranged to allow for expansion or float of the axle.5.20.3 Lubrications-Provisions shall be made for the service Lubrication of all the

bearings unless sealed and lubricated for life. Ball and roller bearings shall be

lubricated before assembly.Gear housings shall be split or designed to permit easy


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removal of the shaft.Gear reduction units should be designed so that gears, shafts

and bearings, as well as bearing cartridges and end pieces, can be pre-assembledas a spare.Drum bearings and supports for the upper sheave block shall be located

so as to equalize the load on track wheels as near as possible.

5.20.4 Bearing Brackets and Housing

Bearing brackets, if not integral with the frame, shall be mounted on a machinedsurface and be kept in alignment by fitted bolts or other equally effective

methods. When shafting is geared together the support structure for all bearing

cartridges should, where practical, be integral and located as close as possible tothe gears and pinions. Heavy caps shall be provided with a means for lifting.

5.21 GEARING:

5.21.1 Gearing types

Gearing shall be spur, herringbone, helical as specified in the IS 4460, 7504. Nosplit gears or overhung gears shall be used without specific approval of the owner.

5.21.2 Gearing Design:

Horsepower ratings for all spur and helical involute gearing shall be based upon

American Gear Manufacturers Association or IS 4460 Fundamental RatingFactors and Calculation Methods for Involute Spur and Helical Gear Teeth.

5.21.3 Allowable Stress (Sac) and (Sat)The allowable stress for contact stress (Sac) and for bending stress (Sat) and

material used shall be as listed for Grade I material as per IS 4460.

5.21.4 Dynamic Factors (Cu) and (Ku)

The dynamic factors for pitting resistance (Cu) and for bending strength (Ku)shall be as per Paragraph 8.3.2 and 8.3.3 of AGMA 2001 B-88 based on the

lowest quality member in the mesh.

5.21.5 Elastic coefficient, (CP)The elastic coefficient (CP) shall be as per IS 4460.

5.21.6 Hardness Ratio Factor (CH)The hardness ratio factor (CH) shall be as per IS 4460.

5.21.7 Service Factors

The service factors (CSF) and (KSF) shall be used as per IS 4460.5.21.8 Maximum and Minimum Gearing Face width:

The gearing face width shall be a maximum of 1.4 times the pinion pitch diameter

and a minimum of 3 times the circular pitch.5.21.9 Gear Design Loading

Hoist gear loading for bending strength and pitting resistance shall be based on

the torque required to lift the rated load plus hook block and/or lifting

beam.Travel drive gear ratings for bending strength and pitting resistance shall be

based on 2 times the 60 minute motor rating for series wound constant potentialD.C drives, and 1.7 times the 60 minute motor rating for A.C motors and

adjustable voltage D.C drives without motor field weakening, or wheel slip atmaximum wheel load (0.20 friction factor) whichever is lower. Due

consideration shall be given to the maximum brake torque which can be applied to

the drive.5.21.10Dynamic Response


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Where unusual drive arrangements are employed the dynamic response of the

system should be analysed to ensure that any additional loadings are identified.

5.21.11Drum Gear Alignment-The effects of trolley frame and rope drum deflections on

the alignment of the hoist drum gear and pinion shall be considered.5.22 MACHINING REQUIREMENTS5.22.1 Machining and Inspection-All gears shall be 20 pressure angle full depth tooth

form and shall have a full root radius unless this compromises other designconsiderations. The wall thickness over the keyway of pinions shall be atleast

equal to the tooth depth and the rim thickness of gears shall be atleast 1.2 times

the tooth depth. Gears shall not have a shoulder or step left in the fillet area.5.22.2 Bores - Bores for gears requiring heat treatment shall be finish-machined or

ground to size after heat treatment and shall be no harder than 345 BHN for Class

G-1; 300 BHN for Class G-2; and 269 BHN for Classes G-3 and G-4.5.22.3 Keyway Tolerances - Keyway tolerances to be in accordance with relevant Indian

Standards.5.22.4 Effective Case Depth - The effective case depth for carburised and hardened gears

is defined as the depth below the surface at which the Rockwell C hardness hasdropped to HRC 50.

5.23 GEAR BOXES

5.23.1 All gears shall be completely enclosed in gear boxes which shall be attached torigid supports. All gear boxes except for drum ring gears shall be oil-tight and sealed

with compound or gaskets.The bottom of the gear boxes shall be split horizontally

above the oil level. Easily accessible drain plugs and breathers shall be provided.Oil level dipsticks shall go directly into the main body of gear box.

5.23.2 Openings shall be provided in the top section for the inspection of gearing at meshlines. Gear box inspection cover plates should provide reliable sealing, and be

easily opened and resealed.

5.23.3 In Classes M7 and M8, bearings shall be mounted in cartridges. Cartridges shallbe held in place by tapped bolts and flanges. Splash oil lubrication of bearings

may be used unless otherwise specified. Oil pumps shall be used if vertical

gearing exceeds two reductions. On horizontal gearing, the oil level shall be

above the smallest gear.Oil seals shall be sized to allow replacement with split seals. Through bolts should

be used to hold the gear cases together and to mount the gear box to its base.All

gear cases shall be mounted on machined surfaces. Shims shall not be used.5.23.4 Gear box seats shall be of sufficient size to allow the installation of shear blocks to

locate the gear box positively.

Gear boxes shall be provided with lifting lugs that are suitable for use in liftingthe whole gear case assembly without tilting.

5.23.5 The gear box mounting shall be machine cut, hardened and profile ground to

relevant Indian Standards and shall be seated and positively located on machinedsurface. The fabricated gear boxes shall be stress relieved before machining. The

internal surfaces of the gear box shall be painted with oil resisting point. All

gearing not enclosed in Gear boxes which may constitute a hazard under normal


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operating conditions shall be guarded with provision for lubrication and

inspection.Guards shall be securely fastened.

5.24 LUBRICATION5.24.1 All lines shall be located so as to provide the maximum natural protection, and at

the same times lines should be positioned so that ordinary repairs can be made

without complete removal of the lines. All lines shall be fastened to the cranesstructure.

5.24.2 Centralised automatic grease systems should be considered on trolleys. Manual

pumps should be considered for bridge drive assemblies. Flexible hoses should beutilised at components end for easy removal.

5.24.3 Provisions shall be made for lubricating all bearings unless sealed or lubricated for

life, matting gears and chain and sprockets arrangements, where necessary easy accessshall be provided.

5.24.4 A lubricating chart shall be provided indicating all the lubricating points with Red

colour paint, the type of lubricant and recommended frequency of lubrication.

5.25 LINE SHAFTING AND COUPLINGS:

5.25.1 Floating shaftWhere possible, the flexible halves of half flexible couplings shall be mounted on

the floating shaft. Couplings shall be located close to the bearings and beprovided with substantial removable guards which shall extend beyond the ends

of the hubs and overlap with the coupling hub OD. Where half-flexible couplings

are used, the couplings shall be located close to the bearing on the end truck andthe adjacent line shaft bearing shall not be closed than 1250 mm.

5.25.2 The load shall be transmitted between couplings half by means of fitted bolts. For

shaft speed below 400 rpm, the following maximum bearing spacing shall bepermitted.

a) 3.5 m for 75 mm diab) 4.25 M for 90 mm diac) 4.5 M for 100 mm diad) 4.85 m for 115 mm dia

5.25.3 For shaft speed in excess of 400 rpm, the above spacing shall be reduced as

necessary to avoid harmonic vibrations. Supports for motor and gear reduction

units shall be welded structural steel, rigidly connected to the crane girder. Bolts

for fastening bearing brackets, motors and gear reduction unit shall be accessiblefrom above the foot walk. Angular deflection of bridge line shafts at torque shall

not exceed 0.3 degree/m of shaft length.

5.26 RAILS5.26.1 Joints on trolley rail shall be welded or made by using standard joint bars. There

shall be no bolt holes adjacent to the welded joint. Where joint bars are used, the

joined ends of the rails shall be laid without openings between the ends.The railsshall be as per CR rail.

5.26.2 For box girders, rails shall be fastened in place by suitable clamps. The rail

clamping shall be of soft mounting system, consist of pad and clips. The pad shallbe reinforced with galvanised steel vulcanised to and totally encapsulated by the

elastomer. The clips should provide positive lateral rail and pad restraint and

vertical restraint. The clips shall be of spring clips presses the rail against the pad.


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The clamps shall be spaced at not more than 900 mm centres. Heat treated rail

shall be used for increased rail life. The rails shall be welded together by flashbutt welding or thermit welding.

5.27 OPERATORS CABIN5.27.1 Type and location - The operators cabin may be of the fixed/moving type as

required by the purchaser.5.27.2 Structure - The cabin shall be rigidly built of structural steel and fire proof

material and shall be braced to prevent movement between cabin and supporting

members. It shall be supported by rivets or bolts in shear. The head room of thecabin shall not be less than 2 M.

5.27.3 In ladle cranes, other cranes handling hot materials and outdoor cranes, cabins

shall be totally enclosed, unless otherwise specified.5.27.4 The cabin of outdoor shall be weatherproof.

5.27.5 Cabin Access - The entrance to the cabin shall be fitted with a door located for

safe access. The cabin floor shall be extended outside the cabin on the sidecontaining the door, and if necessary, sideways also to form a platform unless

otherwise required. Suitable hand railing should be provided on the platform.5.27.6 Accessibility to the bridge platform shall be through the stairs.

5.27.7 Visibility and Field of vision - Cabins shall be so designed that under all operatingconditions the field of vision of the driver is adequate.

5.27.8 Lighting, heating, ventilation and air-conditioning: Fixed service lighting shall be

installed to provide glare free illumination in the crane cabin.5.27.9 All cabins shall be provided with an air circulating fan of minimum sweep 400

mm.

5.27.10 All air-conditioned cabins shall be fitted with a suitable hydraulic doorcloser and temp in the cabin shall be around 25C.

5.27.11 A suitable Co2 type fire extinguisher shall also be provided.5.27.12 The cabin shall have a robust seat with a fixed or hinged base and a durable

upholstered squab. The seat shall be capable of withstanding severe braking

force.

5.28 MEANS OF ACCESS5.28.1 General requirements - Safe means of access shall be provided to the drivers

cabin and adequate hand-holds and foot-holds shall be provided, where necessary.

5.28.2 Platform - Every platform shall be securely fenced with double tiered guard railshaving a minimum height of 1.1 metre.

5.28.3 Ladders - Sides of ladders shall extend to a reasonable distance above the

platforms. Vertical ladders exceeding 3 metre in length shall be provided withback safety guards.

5.29 GUARDING -5.29.1 All gear wheels, pinions and chain drives shall be totally enclosed. Effective

guards shall be provided for revolving shafts and couplings. Long travel cross-

shafts and couplings above the top platform shall be guarded wherever necessary.

The sheaves of hook blocks shall be guarded to prevent the trapping of a handbetween a sheave and the in-running rope and shall be enclosed except for rope

opening.

5.30 WEATHER PROTECTION


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5.30.1 For outdoor cranes all electrical and mechanical equipment shall be adequately

protected from weather. All weather proof covers shall be easily removable.

5.31 PAINTING -5.31.1 Before the despatch of cranes, the complete crane covering structural, mechanical

and electrical parts shall be thoroughly cleaned of all dirt, grease, scales, rust and

given a single coat of primer. All components shall be given two finishing coat ofpaint of colour as per customers choice.

5.32 HANDLING FACILITIES:5.32.1 Suitable structures at all four corners for handling the track wheels, should be

provided. However for all outdoor goliath and semi-goliath cranes, this facility

shall be provided.

5.32.2 All cranes shall be provided with jack pad on both end carriages and trolleystructures in such a way so as to facilitate removal of wheels, wheel bogie and

compensating bogie.

5.33 BRIDGE AND TROLLEY DRIVES-5.33.1 Bridge and trolley drives arrangements may cover most types of crane drives

regardless of the number of wheels.5..33.2Bridge drives- Bridge drive shall consists of one of the following arrangements,

and these arrangements cover most four or eight wheel crane drives.5.33.3 DRIVE I-The motor is located near the centre of the bridge and connected to a

self-contained gear reduction unit located near the centre of the bridge. Output of

the Gear reduction shall be connected directly to the truck wheel axle by means ofsuitable shafts and couplings.

5.33.4 DRIVE II The motor is connected to a self contained gear reduction unit located

near the centre of the bridge. The Truck wheels shall be driven through gearspressed and keyed on their axles or by gears fastened to, or integral with, the

Truck wheels and with pinions mounted on the end section of the cross-shaft. Theend sections of the cross-shaft shall be connected by suitable couplings.

5.33.5 DRIVE III-The motor is located at the centre of the bridge and is connected to the

cross-shaft and gear reduction units with suitable coupling. Self-contained gearreduction units located near each and of the bridge shall be either directly

connected to the wheel axle extension or connected to wheel axles by means of

shafts in the suitable couplings.

5.33.6 DRIVE IV-The motors are located near each end of the bridge without torqueshafts. The motors shall be connected to self-contained gear reduction units. The

gear reduction unit shall be applied to the truck wheels by means of both suitable

shafts and couplings or directly mounted to the wheel axle shaft extension.Another variation of this drive would separate the high speed and final reductions

by locating the motors near each end of the bridge without torque shafts.

5.33.7 DRIVE V-The motor is located near the centre of the bridge and in connected to aself-contained gear reduction unit located near centre of the bridge This reduction

unit shall be connected by sections of cross-shaft having suitable couplings to

self-contained gear reduction units located near each end of the crane, and these inturn connected to truck wheel axle by means of shafts with suitable coupling.

5.33.8 DRIVE VI-The motors are located near each end of the bridge and connected with

a torque shaft. On the drive end, the motors shall be connected to self-contained


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gear reduction units by suitable couplings. The output of the gear reduction units

shall be connected directly to the truck wheel axle by means of suitable shafts andcouplings.

5.34 TORSIONAL DEFLECTION AND VIBRATION

Natural frequency and amplitude of total torsional deflection of the drive system

should be determined. Low frequencies and large total torsional deflections areundesirable for crane operation.

5.35 MOTION LIMITING DEVICEPositive by operated hoisting motion limiting devices shall be provided that stopsthe upward and downward motion when predetermined level is reached to prevent

over winding or over unwinding.

NOTE:-The limiting device shall be regarded as a safety feature and not as aroutine operational means of stopping. Where normal operation of the crane

necessitates frequent approach to the upward limit, an additional motion limiting

device shall be provided that operates independently and require manual settings.

5.36 CROSS TRAVEL AND LONG TRAVEL LIMITING DEVICES:

The limiting devices shall prevent the following conditions:(a)Over traversing and over travelling, and(b)Collision where two or more crane/Trolleys operating on the same track.

5.37 LOAD INDICATION AND LOAD LIMITING DEVICESLoad indication and limiting devices are recommended it weights of objects to be

lifted are not known accurately. When fitted, they shall sense the load on thecrane by means other than the current consumed by the hoist motor. If the load

lifted is more than SWL load limiting devices shall stop further hoisting operation

till the load is removed or reduced.

5.38 DRAWINGS AND DOCUMENTS

Following drawings and documents shall be submitted for approval of thepurchase before manufacturing of the crane:

(a) GA drawings of the crane(b) GA drawings of crab/Trolley(c) GA drawings of individual mechanisms(d) Drawings of bridge, end girder and their connection(e) Sub-assembly drawing for wheels, hook blocks and hoist drums.(f) Calculation for selection of motor, reducer brake, couplings, etc.


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SECTION 3 ELECTRICAL EQUIPMENT

6.1 POWER SUPPLY

6.1 GENERAL-This document deals with a.c. low-voltage systems upto 1000 V.

The power supply system should comply with relevant Indian Standards. Voltage

variation at the point of supply to crane DSL system be limited to 5% +5% of therated voltage under normal operating conditions. The End User should ensure this with

respect to number of cranes in the bay with dedicated feeder, etc., In applications with

very long cabling distances it may be necessary to limit the voltage variation further. Theallowed per cent voltage drop in the different parts of the power supply need to be

considered case by case. The type of the power supply grounding may have significant

effects on the requirements of the crane electrification. The type should always be agreedbetween the purchaser and supplier. For Cranes with incoming power requirement higher

than 1000 kVA , the system voltage should preferably be 690 V a.c in order to design

with optimum sizes of conductor , cables , motors and controls. Typical example is LadleCranes.

6.2 DSL SYSTEMS AND ACCESSORIES FOR CRANES6.2.1 General

Down shop lead arrangement using copper, aluminium or steel sections with or withoutshrouding or by using flexible trailing cable arrangement may be used. Use of shrouded

conductors, where ever possible is recommended.

6.2.2 Conductors

Current collecting system shall be provided either by the purchaser or by the crane

manufacturer as agreed by them. Cranes operating on bare conductors shall be equipped

with suitable guards to prevent ropes or suspended load coming in contact with the liveconductors due to swing of the hook block. Down-shop conductors also shall be screened

to prevent contact while handling long lengths of conducting materials from floor.

6.2.3 Current collectors

Unless otherwise agreed to, all collector assembly shall be supplied by the crane

manufacturer. The purchaser shall furnish relevant details depending upon themanufacturers scope of work. Collector rollers or shoes shall be so designed as to avoid

sparking and shall be easily replaceable. Collector assembly shall be mounted on a rigid

structure on the crane bridge. Necessary safe and convenient access shall be provided for

maintenance or replacement of the collectors.

6.3 CROSS TRAVEL CURRENT COLLECTING SYSTEM

6.3.1 General-Cross travel current collecting system shall be with bare conductors or

with shrouded conductors or with trailing cable arrangement. The collection system shallbe provided by the manufacturer.

6.3.2 Conductors-Cross travel conductors for the main crab shall be mounted on the

main bridge platform and not inside the main girders. Conductors for auxiliary crabs shallbe mounted suitably above the level of auxiliary crab rails. Cross travel conductors shall

be arranged so that they are all accessible for maintenance from atleast one side along the

whole length. Bare conductors mounted on the bridge adjacent to a walk way along thebridge shall be completely screened from the walkway.

6.3.3 Collector assembly-Collector assembly shall be rigidly mounted on the crab and

shall be provided with reasonable accessibility to all parts for maintenance purpose.


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6.4 EARTHING

6.4.1 General-The crane structure, motor frames, and metal cases of all electricalequipment including metal conduit or cable guards shall be effectively connected to earth

complying with Indian Electricity Rules (See IS 3043). A flexible metallic tube or duct

may not form an effective earth connection. The crane wheels shall not be used as means

of earthing.Where the crane is connected to the supply by flexible cord or flexible cable,the crane shall be connected to earth by means of a separate earthing conductor enclosed

with the current carrying conductors.Travelling cranes connected to the supply through

collectors shall be effectively earthed through a fourth lead or through a set of collectorssliding on the gantry rail with reference to IS 3043.The purchaser shall arrange for the

earthing of the gantry and/or the long travel earth conductor.

6.4.2 Control Circuit Earthing

One end of the secondary winding of control circuit transformer shall be earthed. One end

of the coil of all relays and contactors shall be connected to earth side of the control

circuit supply and this connection shall not be interrupted by any fuse or contact.In thecase of dc control circuits one pole of the rectifier shall be earthed.

6.4.3 Magnet Earthing

The magnet frame shall be bonded to the crab by the earth connection via the magnetlead, the magnet coupling, the magnet cable and an extra slip-ring on the cable drum.

6.5 CONDUCTOR BARS, CABLE REELS AND FLEXIBLE CABLES

The following three important considerations must be taken into account in dimensioninginsulated wires or cables:

- The temperature rise in normal condition.

- The temperature rise in faulty operation and on short-circuit.- The voltage drop

The following clauses in IEC 60204-32 defines the basic requirements.Clause 13.7 Flexible Cable

Clause 13.8 Collector wires, collector bars and slip ring assemblies

Clause 14.4.3 Connections to cranes and between moving parts of the crane.According to 13.8.2 of IEC 60204-32, where ever collector wires, conductor bars and

slip-ring assemblies are installed as part of the protective bonding circuit, they shall not

carry current in normal operation. Therefore, the protective conductor (PE) and the

neutral conductor (N) shall each use a separate collector wire, collector bar or slip-ring.The continuity of the protective conductor circuit using sliding contacts shall be ensured

by taking appropriate measures (e.g. duplication of the current collector, continuity

monitoring). The continuity of any protective bonding connection with sliding contactsshall be ensured e.g by duplication of the current collector (one set). Additionally, when

sliding contacts are used to supply power to electronic drives, double collectors should be

used also in phase collectors to avoid noise and hardware failures which may occur if acontact cuts off momentarily (2 sets of current collectors).

6.6 CALCULATION OF CROSS-SECTION OF CONDUCTORS

These requirements apply both to the power supply to the crane and also to cabling withinthe crane.In general the selection of cable / conductors depend on the following :

a) General operating conditions

b) Ambient air temperature


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c) Methods of installation

d) Groupinge) Intermittent duty applications

6.6.2 Co-ordination between conductors and protective devices

a) In all cases, the following relationships shall exist:

Ib < = InIb < = Iz

Where

In = is the nominal current or current setting, in amperes, of the over current protectivedevice

Iz = is the effective current carrying capacity, in amperes, of a cable for continuous

Service under the particular installation conditions concerned.b) Where the over current protective device is intended to provide overload protection,

the following relationships shall exist:

Ib < = In < = IzI2 < = 1.45 x Iz

where I2 is the minimum current, in amperes, that when maintained for 1 hour will causethe protective device to open the circuit

c) Where the over current protective device is intended only to provide short circuitprotection:

In may be greater than Iz and

I2 may be greater than 1,45 IzHowever, it should be remembered that the higher In is in relation to Iz , the greater is the

possibility of exceeding the ultimate short-circuit conductor temperature in the event of a

short circuit. That is particularly true in the case of the smaller conductors ranging in sizeup to 16 mm

2.

6.6.3 Short circuit protection of conductors

The conditions to be met for short circuit protection is:

t xIs

k= , where:

s = conductor cross section in mm2

t = switch off time for protection against hazardous shock currents max 0.2 to 5 s, as

applicable.

I = effective short circuit current in amperes expressed for a.c as the rms.K = factor for conductor [As / mm

2] when insulated with the following material,

= 76 for PVC insulated Al conductors

= 115 for PVC insulated copper conductors

= 141 for Rubber insulated copper conductors= 132 for SiR insulated copper conductors

= 143 for XLPE insulated copper conductors= 143 for EPR insulated copper conductors

6.6.4 Calculation of the cross-section in relation to the admissible voltage drop

The voltage drop must be considered, paying attention to the fluctuation and the voltage

drop within the power supply. For very long supply lines, not only the resistive but also


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the inductive part of the supply impedance need to be taken into account. Drop due to

reactance should also be checked.The cross-section of the conductors should bedetermined by taking into account the mechanical strength required and the electrical

load to be carried. Looping cable may be provided in parallel after checking the limit of

voltage drop.When calculating the voltage drop, the most unfavourable position of the

hoisting appliance in relation to the supply point must be considered.When calculatingthe admissible voltage drop on a supply line used by several hoisting appliances, the start-

up (ID) and rated (IN) currents of the motors operating simultaneously must be taken into

account.Table No: 2.1

For all lifting appliances as a whole

Motion-1 Motion-2 Motion-3 Motion-4Number of hoisting

appliances on one

main contact line (highest rating in kW)Motions in decreasing order of

power.(kW)

1 X X

2 X X X

3 X X X4 X X X X

5 X X X X

Two hoisting

appliances workingtogether

X X X X

Table No: 2.2

For all the hoisting appliances as a wholeNumber of

appliances on one

main contact lineMotion-1

ID IN

Motion-2

ID IN

Motion-3

ID IN

Motion-4

ID IN

1 X X

2 X X X3 X X

4 X X X

5 X X X X

2 appliances

Working togetherX X X X

Notes for the calculation:a) In this clause, the rated current (In) should be considered not necessarily to

mean the name plate current of the motor but the current drawn by the motor at

full rated load. (ie. FLC corresponding to mechanical KW) for slip ring motors.

b) In case of squirrel cage motor to be controlled by an electronic drive (soft-starter, frequency converter, etc.,) the maximum current during any phase of

operation should be considered as start-up current, although the highestcurrent does not necessarily occur when starting the motion. With direct

starting the ID (starting current) is typically 5 to 10 times In. With electronicdrives the start-up current depends on the converter type and on its

adjustments; with frequency converters the ID is typically below 2 times IN

(nominal current).


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c) For slip-ring rotor motors, consider ID to be approx. 1.8 x In.

d) For drive with n motors in parallel, apply n x ID or n x IN.e) In case two or more hoisting appliances are working together, they should

be considered as one appliance by using the sum current (ID or IN) of each

joint motion.

f) In case the power supply also feeds other (continuous) loads such aslighting, hydraulic pumps, lifting magnets or other cranes, the current drawn

by these devices need to be taken into account.

For a three phase power supply, the required minimum cross-section (S) of copperconductors can be calculated with the formula:

23 1 cos1 totX XI X

S mmuXK

=

, where

l = Effective length of the line (m)

Itot = Sum of the above calculated (ID and IN) currents (A)

u = Admissible voltage drop (V)k = Electric conductivity [ x mm2 x 2-1]-1cos = Power factor.Calculation for voltage drop: (for reference purpose)

u= 3 x Itot x l x Z where Itot = Net current load on DSLl = effective length ( l/2 for mid point feed )

Z = Impedance (/km)6.6.5 Calculation of the minimum cross-section in relation to the thermal capacity of

the conductors

When calculating the cross-section for the conductor bar, which supplies several hoistingappliances, the actual simultaneous operation of the drive motors must be taken into

account.Notes for the calculation:

a) In this clause, the rated current (In) should be considered not necessarily to meanthe nameplate current of the motor but the current drawn by the motor at full ratedload.

b) In case n>1 motors are driven in parallel, consider: In = n x In (In = nominalcurrent for one motor)

c) In case two or more hoisting appliances are working together, they should behandled as one by using the sum current of each joint motion.

d) In case the power supply also feeds other (continuous) loads such as lighting,hydraulic pumps, lifting magnets or other cranes, the current drawn by these

devices need to be taken into account.The maximum allowed conductor temperature shall not be exceeded during normal

operation. Conductor cross-section should be selected according to manufacturersspecifications.

6.6.6 Installation of Cablesa) While selecting cables consideration shall be given to factors like ambient

temperature, grouping and disposition of cables, and the limitation of the voltage


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drop. The cables selection, testing shall be as per IS: 694, IS 554 and IS 9968 part

1 and Part 2.b) Protection: All cables shall be adequately protected against mechanical damage

and metal trunking may be used if desired. If electric conduit is used it shall be

welded conduit complying with the to relevant Indian Standard.

c) Where cables are drawn into a steel tubes, the steel tube shall be heavy gauge,welded or solid-drawn, screw-jointed and drained.

d) For outdoor cranes, except where flexible unarmoured cables are essential, cables

shall be either armoured or enclosed throughout their length in galvanizedtrunking or conduit either flexible or rigid. A flexible metallic tube or duct shall

not be used as an earth connection. Taped and braided varnished cambic insulated

cables shall not be used for out-door cranes.e) Installation; The cable and wiring systems for each motion shall be independent

and common returns shall be avoided. Main cables and controlled wiring shall be

effectively separated. Where there is incidence of direct radiation of heat, thecable shall be protected by a shield of sheet metal.

f) Cables shall be adequately secured to the main structure of the crane having dueregard for the weight of the cable and the possibility of vibration. Where mineral

insulated metal cables are subject to the effects of high transient voltage they shallbe suitably protected by the use of surge limiting devices.

g) Cables remaining alive when a main isolator is opened shall have metallicprotection and shall be separately installed.

h) Cable runs shall not be installed in any place where they will impede the crane

drivers field of view.i) Due consideration shall be given during the design of the crane to make suitable

provision for cable runs and to avoid cable runs in locations where hightemperatures and mechanical damage are likely to be experienced under service

conditions. The cables should be easily accessible and should not hamper the

movement of persons on the crane.j) Suitable precaution shall be taken to prevent the ingress or collection of water or

oil in any part of a conduit or trunking system.

k) Termination: Where trunking is used it shall extend into the electrical compartment

or enclosed units. It shall be terminated as close as practicable to motors, collectorgear and master controllers. Where junction boxes are necessary, as at motors

equipped with flexible tails, these boxes shall be rigidly fixed to the crane

structure close to the end of the trunking. Flexible or rigid conduit may be used toprotect the cables between the trunking and the connected apparatus.

l) Conduit systems shall be continuous to switch boxes and conduit outlets.

m) Cable tails shall be suitably insulated and mechanically protected, and shall besuitably supported with insulated cleats, where necessary, to ensure rigidity.

n) Identification: Cores of multicore cables shall bear a distinguishing mark or tape.

p) Cable ends and terminals shall be ferruled at both ends and permanently markedwith numbers or letters to correspond with the diagrams or connections to be

supplied.

6.7 ELECTRICAL PROTECTIVE AND SAFETY EQUIPMENT


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6.7.1 PROTECTIVE EQUIPMENT

6.7.1.1 General-Suitably located efficient means shall be provided to protect every partof a system from excess current and voltage to prevent danger or damage. Enclosures

having minimum degree of protection IP 41 shall be provided for all electrical

equipments except for motors and resistors.

Main Isolating switches: Main switches used for isolating shall comply as per IS 2516part 1 and 2. The main metal-clad isolating switch shall be provided on the crane bridge

in an accessible position and connected directly to the long-travel collectors or terminal

box in case flexible cables are used. The switch shall be located as close as possible to thelong-travel collectors or terminal box, unless its position be otherwise specified. On fixed

cab cranes (See Fig. 1) it shall isolate all circuits, except the crane lighting circuits,

warning lighting circuits, communication circuits; and in ac cranes, the circuit of thetransformer supplying the portable lighting socket outlets. On moving cab cranes, it shall

isolate all circuits except bridge lighting circuits, warning lighting circuits and in ac

cranes the circuit of the transformer supplying the portable lighting outlets. This isolatingswitch shall be unfused, unless high betaking capacity fuse protection is specified.

FIG. 1 DIAGRAM OF MAIN ISOLATING SWITCHES AND FUSESREQUIRED FOR FIXED CAB CRANES

On moving cab cranes (See Fig. 2) an additional main unfused metal-clad isolating

switch shall be provided on the cab structure in an accessible position outside the crane

cab and connected directly to the cross travel collectors or terminal box in case flexiblecables are used. The switch shall be located as close as possible to the cross-travel

collectors, unless its position be otherwise specified. It shall isolate all circuits, except the

crab lighting circuits, circuits arranged to operate warning devices and on ac cranes thecircuit to the transformer for the portable lighting socket outlets on the crab. The

selection, maintenance and installation shall be as per IS 10118, part 1 to 4.Each of the

above main isolating switches shall be rated to carry atleast the combined full-loadscurrents of the two motions of the crane using the largest power (kW) working together

with auxiliary loads such as lifting magnets and shall be provided with a means for

locking it in the OFF position of the switch. The switch cover shall be interlocked withthe operating handle, so that it may not be removed or opened when the switch is closed.

Live terminals inside the switch shall be shielded to prevent accidental contact. A pair of

neon type pilot lamps or other device in duplicate, indicating when the supply to the


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crane control circuits is live, shall be provided in a position visible to the driver from his

normal working position. If specified, the main isolating switch on the bridge shall befitted with a pair of auxiliary contacts which will be closed when the main switch is open

and vice-versa, to operate the crane warning lights

Fig. 2 DIAGRAM OF MAIN ISOLATING SWITCHES AND FUSES

REQUIRED FOR MOVING-CAB CRANES

6.7.2 Electrical Protective Device

6.7.2.1 General

If electrically operated contactor equipment is used for control of all crane motions, the

protective equipment shall be in accordance either with Scheme A, in which each motionhas separate protection, or with Scheme B, in which an overload of any motion trips off

the crane supply. If drum controllers or master controllers are used for the control of all

motions, the protective equipment shall comply with Scheme B. Also it is more oftenrequired that in master controller operated crane, overload of any motion should not trip

the complete crane circuit, but should trip the individual circuit. In general, overloadprotection shall be of electromagnetic type with time delay. Thermal overload relays in

conjunction with high rupturing capacity fuses or manual reset type overload relays may

be provided if agreed by the purchaser.Where a motion is ward-Leonard controlled, provisions shall be made for:

a) Protection in case of motor field failure;

b) Protection against the motor creeping when the controller is in the off

position; andc) Tripping of the generator field circuit with suppression of generator voltages

instantaneously when there is an over current of 250 percent in the generator-

motor loop; or after a time-lag when there is a sustained over current of lowervalue.

Operation of any of the above protective devices shall automatically apply the electro-

mechanical brakes on the relevant motion. If other systems of control or mixed systemsare specified, the protective equipment shall be in accordance with the recommendations

of the control gear manufacturer. An indelible circuit diagram of the protective equipment

shall be provided in the electrical equipment compartment.

6.7.2.2 Protective device common to all motionsAs minimum equipments of protection, electromagnetically operated contactors or

manually operated circuit breakers fitted with no volt release capable of cutting off the


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power supply to the motion drives with under voltage protection shall be provided.

Suitable protection against short circuit shall be provided at each of the isolator positions.The circuit breaker of the main contactor shall be rated to carry at least the combined full

load currents of motors for any two motions having largest powers and auxiliary loads

such as magnet, etc., if specified by the purchaser that more than two motions may be

operated simultaneously, circuit breaker/main contactor shall be rated to suit therequirement. In appropriate cases, high rupturing capacity fuse may be provided. The

circuit-breaker shall incorporate thermal and electro-magnetic overload protection device

for protection against sustained overload and short circuit condition. If adequateprotection against short circuit is to be provided at each isolating positions, there will be

either HRC fuses or MCCB/ACB in each isolating position. As HRC fuses may lead

single phasing only MCCB should be provided in each isolating position. The circuitbreaker or main line contactor should not be rated to carry magnet full load current as

magnet supply is taken before the circuit breaker/main line contactor. The breaker shall

have adequate rupturing capacity to withstand and clear fault current of the system. Ifspecified a suitable control circuit may be provided for this circuit-breaker to prevent it

from being closed when the main contactor of a particular motion has failed to open,although the corresponding controller has been brought to its zero position.

6.7.2.3Scheme A Protective Device for Individual MotionsThe provision of overload protection with adjustable inverse time log overload release

shall be under-voltage release and with overload. The minimum provision of overload

protection shall be such that all supply lines except one to each motion shall be providedwith adjustable inverse time-lag overload releases. These shall be connected as close as

possible to the contractors they control and shall be set to trip the circuit of the motion

controlled when carrying 200 percent of the full load current of the motor, after a time-lag of not more than 10 s. It shall not be possible to reinstate the current supply to the

contactor closing coils of a motion until the master controller for that motion is returnedback to the off position.

6.7.2.4 Ac Instantaneous Release Single Pole over Load: Protective Device for

Individual Motions:

Any motor having its power less than one-third that of the largest motor and served by

the same common overload release, shall be protected by a separate overload release.

However, normally instantaneous release of overload relays are not used for individual

motion and circuit breaker is tripped by its own overload. In crane with circuit breakeroverload protection is provided by circuit breaker. In cranes with line contactor one triple

pole magnetic overload relay rated for total crane power may be provided to trip the main

contactor. Adjustable overload releases shall be provided to trip the main contactors orcircuit-breakers and shall be connected as close to them as possible. The minimum

provision for over current protection shall be as given below:

a) one instantaneous release in a common line feeding all motions set to tripthe main contactors or circuit breakers instantaneously when the current

rises to 250 percent of the value specified above; and

b) One inverse time-lag release in each other line feeding each motion, set totrip the respective motion when carrying 200 percent of the full load current

of the line, after a time-lag of approximately 10 s.


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It shall not be possible to reinstate the current supply to the common main contactor

closing coils, or complete the under voltage circuit of the circuit breakers until the mastercontrollers for all motions are returned to the off position.

6.7.2.5 Protective Devices for Motor circuits

The number of overload devices and their position shall normally be in accordance with

the arrangements shown in Table 14. If specified by the purchaser, other arrangementsgiving protection not less than any of these shall be considered as complying with the

specification.

Table 14 Normal Requirements for Number of Protective Devices for Circuit

Dc Supply

No line earthed One line earthed

3-phase acsupply

2 per motion in separate lines 1 per motion

connected in the non-

earthed line.

3 per motion in

separate lines

6.8 Contactors

Reversing contactors shall be interlocked, preferably mechanically as well as electricallyso that only one directional contactor can be in the closed position.

6.9 Control Switch Fuse

Operating coil circuit of the main contactor or control contactor in case of cranes withcircuit breaker. A double pole control switch fuse shall be connected in the operating coil

circuit of the contactor. Miniature circuit breaker as an alternative to control switch fuse

may also be used.

6.10 Emergency Switches

A mushroom head push button or a prominent switch for emergency stop shall be

provided at each control facility to switch off the total crane supply or to de-energize

the main contactor common to all the motion drives. In the case of dc cranes, rheostatbraking shall be applied to the hoist motions. When any circuit breaking device is open

no main pole on the nominally dead side shall be made alive by a parallel circuit inemergency.The emergency switch shall be so located as to be readily available for

prompt use by the operator in case of emergency. If specified by the purchaser or when

the crane span is larger than 20 m, the number of emergency stops shall be more than

one. A reset button shall be provided if required by the purchaser. The emergency stoppush-buttons or switches shall be connected in the operating coil circuit in the case of a

contactor and in the under voltage release circuit in the case of a circuit breaker.

6.11 Off-Position Interlocking

Electrical interlocking shall be provided to prevent inadvertent starting of the motions, in

the case when power is lost, without the controller being brought to the off position onrestoration of the supply.

6.12 Pilot Lamp

A red pilot lamp shall be connected to indicate that the crane is ready for operations and it

shall be so located that it is visible to the operator. The pilot lamp shall be connected sothat it indicates whether the control supply is ON or OFF or the contactor is CLOSED or

OPEN.

6.13 Main feature of built-in crane weighing system (Load Cell)


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- The load cell shall be of compression type and IP 68 protection.

- The power supply shall be 230 V ac or 110 V ac 50 Hz single phase.- The load cell shall be placed in such a way that the load which is inert on the

equalizing pulley/bar is transferred to this load cell by a pivot assembly.

- The built-in crane weighing system should have local indicator, processor

based type, LED displa y, IP 55 protection, shall be located on the controlcabin of the crane.

- The built-in crane weighing system should have remote indicator, LED

display type, minimum visibility range of 50 m, shall be located on the cranegirder.

- The resolution shall be in the order of 5 kg.

- The system shall have the provision of tripping the circuit in case ofoverloading the cranes and should serve on an additional overload safety

device.

6.14 Auxiliary Isolating Switches and Fuses

Auxiliary switches used for isolating shall comply with the relevant Indian Standards. If

specified, an isolating switch shall be provided to isolate all supply lines to the maincircuits of each motion. Double-pole high breaking capacity fuses shall be provided on

each motion control panel. If specified a double-pole isolating switch shall be providedon each motion control panel to isolate the control circuits. Miniature circuit-breaker as

an alternate to control switch fuse is also permissible.Metal-clad isolating switches with

cartridge fuse protection in all lines shall be provided to isolate all supply lines to each ofthe following distribution boards or circuits where they exist. The cartridge fuses shall

comply with the relevant Indian Standards.

a) Fixed cab cranes:

- Distribution board for all crane lighting circuits including warning lighting

circuits.- Distribution board for auxiliary circuits other than lighting circuits.

- Magnet circuits.

b) Moving cab cranes

- Distribution board for bridge lighting circuits including warning lighting

circuits.

- Distribution board for all crab lighting circuits.

- Distribution board of boards for auxiliary circuits other than lighting circuits.- Magnet circuits.

In fixed cab cranes, the crane lighting circuit isolating switch shall be connected directly

to the long travel collectors and located in the immediate vicinity of the main isolatingswitch on the bridge.In moving cab cranes, the bridge lighting circuit isolating switch

shall be connected directly to the live side of the main isolating switch with cables as

short as possible. The switch shall be located on the bridge in the immediate vicinity ofthe main isolating switch. The crab lighting circuit isolating switch shall be connected

directly to the cross-travel collectors and located in the immediate vicinity of the main

isolating switch on the crab.

6.15 Distribution Board

Metal clad distribution boards incorporating adequate protection in all lines,

except those directly connected to earth, shall be provided as detailed below to


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feed the following auxiliary circuits where they exist. Distribution boards shall

comply with relevant Indian Standards, except that semi-enclosed fuses shall notbe used.

a) fixed Cab Cranes:

- One distribution board for crane lighting circuits as follows:

- Cab service and maintenance lighting: cab and bridge approaches and electricalequipment compartment lighting; warning lights; in ac crane, the step down transformer

supplying the socket outlets and walkway, and bridge lighting for illuminating the floor

area.- One distribution board for cab heating circuits, fan and air conditioning circuits, if

provided.

b) Moving Cab Cranes:

- One distribution board for bridge lighting circuits, as follows:

- Warning or signal lights; in ac cranes, the step down transformer supplying the

bridge socket outlets, and walkways and bridge lighting.- One distribution board for crab lighting circuits, as follows:

- Cab service and maintenance lighting; cab and bridge approaches and electricalequipment lighting and in ac cranes, the step-down transformer supplying the

crab socket outlets.- One distribution board for cab heating circuits, fan and air-conditioning circuits.

6.16 Auxiliary switches other than Isolation switches

6.16.1Each auxiliary circuit shall be provided with a totally enclosed lightingswitch component complying with relevant Indian Standard (See Appendix

C). These auxiliary switches shall be located as follows:

i. For the equipment in the cab, such as fans and air-conditioners;ii. For the electrical compartment lighting, at the door of the compartment;

iii. For the cab approaches, bridge approaches, and bridge walkway lighting suchthat an operator can illuminate the approaches or walkways without traversing

them

iv. For the bridge lights on the crane bridge, at the crane entrance platform in fixed-cab cranes and on the bridge in moving cab cranes; and

v. Non-fusible double pole emergency switches should be connected in series fo

Documents

Designing of Cranes With Standards