7/28/2019 CAFE4

1/10

_u --

APPBECIATlOII fOil EllGIIlEUS

INSPECTION &MAINTENANCEOFDISTRIBUTIONSUBSTATIONSPreventive Maintenance (PM) programs for distribution substations, overhead linesand equipment are designed to achieve the following goals:

1. Reduce hazard to life and property due to equipment failure.2. Provide safe and reliable power supply to Customers minimizing power

interruptions due to equipment failure for lack of maintenance.3. Attain expected lifetime operation of distribution equipment, thus providing

reasonable return on capital.4. Develop statistics on distribution equipment or component performance to

improve system safety and reliability.Manual (DMM-OI-01)provides general guidelines for the inspection and maintenanceof substation equipment on distribution feeders rated 34.5 kV or below consist of anyof the following:

1. Ground mounted substations, indoor and outdoor,with RMUs.2. Ground mountedpackage substationswithMV air break switchgear3. Groundmounted compact substations with MV switchgear.4. Pole mounted substations with transformer on a platform and controlled by anRMU or Cutout Fuses.Table 4.1-1 Guidelines for Inspection and Maintenance of SubstationEquipment.

231

7/28/2019 CAFE4

2/10

APPRECIITlOIFORIIGIIlEERS

EquJpme...,~Substation Building

2 13.8 kV RMUIEOS (Lucy.:g$yt'olle, MGfEPS) OifandSF!:> gas type '13.8 kV S1=6C:ircuit6neakiiltlri!

7/28/2019 CAFE4

3/10

APPRECIATIONOil ENGINEERS,"

RMU SWITCHGEAR INSPECTION AND MAINTENANCEThe Distribution Maintenance Manual (DMM-02-02) provides precise and adequateinformation on the planned Inspection and Maintenance of 11/13.8 kV RMUswitchgear. Preventive Maintenance is the practice of conducting routine inspections,tests and the servicing of power distribution facilities, consistent with goodeconomics, so that impending faults can be detected and reduced or eliminated. Whilstequipment deterioration is normal, equipment failure is not inevitable.MINI-PILLAR INSPECTION AND MAINTENANCEThe Distribution Maintenance Manual (DMM-02-05) sets out a guideline andprocedure for inspection and maintenance of Mini-pillars in service in order to achievereliable performance and optimum service life.The Mini-pillar is one of the major components of SEC LV Distribution networks.Preventive Maintenance is the practice of conducting routine inspections and servicingof power distribution facilities so that impending faults can be detected and reduced oreliminated.INSPECTION OFMINI-PILLARRoutine inspection of eachMini-pillar in service should be carried out as follows:. Costal/High HumidityAreas

Metal enclosure once every four (4) yearsFiber enclosure once every six (6) years. Other AreasMetal enclosure once every five (5) yearsFiber enclosure once every six (6) years

OVERHEAD LINE PATROLLINGThe Distribution Maintenance Manual (DMM-03-01) provides precise and adequateinformation on the overhead network patrolling. Overhead networks, because of theirexposed nature, can very easily develop additional problems, apart from the normaldeterioration of network components. These include:

233

7/28/2019 CAFE4

4/10

APfRECIATlOUORENGINEERS

. Inadequate clearance over roads, over or near new.

. Buildings, trees and structures.. Storm/lightning damage.

. Third party damage / interference.The scheduling of the overhead linemaintenance is based on the information recordedon the patrol sheet. Likewise the materials, equipments and tools required to effect thenecessary repairs shouldbe evident fromthe patrol sheet.

TYPES OF PATROLLINGTwo types of periodic patrolling are carried out on the overhead distribution linesystem, as follows:Safety PatrolThis patrol is carried out to ensure safety to the public by the visual detection ofpossible hazards. The patrol in open country, desert village and suburban area will beconducted from a vehicle. In congested area, it will be sometime necessary to carryout the patrol on foot.Detailed PatrolThis patrol is carried out on foot along the route of a line in conjunction with plannedmaintenance. The purpose of this patrol is to detect network defects and interferenceprior to the start of planned maintenance on that section of line. Items to be covered inthis patrol are detailed in Fig. 4.1-25.

234

7/28/2019 CAFE4

5/10

APPRECIATIONfO."

A 213~~: '1"",,,-: Detailed SheetI }': \\'1rM ( )3WifeSP~

OfIPOf.e#

!Pole NumOOf"$ I I I I I +I I I I0 FuseCulouts- - u

/Equipment

Cabf&R~

Condl.ldOrSPofaNumbers

; ,*-lI'WIf$.HQ, I"'""ILlat"

.

'

.~F-~.~~17t-~~('frb'RUSH, (2)10(._"",'''''''''_~T''''''''''''''-"""-"""'---- Md OfO!-tJ....Fig. 4.1-25 Detailed Patrolling Sheet (cont'd)

235

AmDi;ii$OO: Detailed Sheet

,: j14Wims. fPug& Fee.dEldN:afueJararimPo.#Of PoIa' I

P

7/28/2019 CAFE4

6/10

mREeI4T10BJORENGINEERS'II:lU,.lII~;I'I.i

236

7/28/2019 CAFE4

7/10

,or,,1' APPRECIATIONFORENGINEERSREVIEW EXERCISE1. Match the left and right column shown below.

2. Read the following statements then choose TRUE or FALSE

237

1. A padlocked A) The operation of anyone fuse operating on a trip bar gives triplehinged flap pole tripping of the switch fuse.

2. Interlock lever B) Restricts access to the operating shafts of the switches.3. Striker pin fuses C) prevents the switch being operated through fromON to EARTH4. Room substation. D) SupplyLVnetwork in residential and commercial areas.5. Platformmounted E) The high tension is supplied to the transformer either by overhead

transformers lines or byunderground cables from anRMU.6. Dedicated sls F) High tension is supplied to the transformer byUIG cable7. Unit substations G) Installed outdoor to receive incoming cables from the LV panels

and outgoing cables for service connections.8. Pad mounted H) Installed in consumer's building, used for schools, apartment

transformer buildings, commercial buildings, industrial buildings andcompounds.

9. Mini-pillars I) For one customer.

1. (SF6)is an inert, light gas having bad dielectric and arc extinguishing properties.2. Same SF6gas is recirculated in the circuit, hence the big requirement of SF6gas.3. The maintenance required for RMU switch is minimum.4. The life of metallic parts and contacts are longer in SF6gas.5. SF6is a gas at low temperature and pressure.6. Moisture has low effect to the properties ofSF6 gas.7. The SF6is a chemical inactive gas.

7/28/2019 CAFE4

8/10

238

7/28/2019 CAFE4

9/10

~ APPBECIAJIOIIOIHNGIHEERSDEMONSTRATE DISTRIBUTION NETWORK

IN OUTSIDE YARD

TASK 4.1-1IDENTIFY PRIMARY DISTRIBUTION EQUIPMENT

PROCEDUREl.2.

Study the following steps of the performance sheet, carefully.Go to outside distribution equipmentyard.Identify and state the purpose of a distribution transformer..

4. Identify and state the purpose of distribution substation with pole mountedtransformers.

5. Identify and state the purpose of a distribution substation with platformmounted transformers.

6. Identify and state the purpose of a distribution substation with pad mountedtransformer.

7. Identify and state the purpose of an indoor (consumer's type) primarydistribution substation. Go inside and point to Circuit Breaker and_instrumentson switchgear.

8.9.

Identify and state the purpose of a primary distribution overhead line.Identify and state the purpose of a primary distribution underground cablefeeding an overhead line.

10. Identify and state purpose of a cable term.

239

7/28/2019 CAFE4

10/10

APPRECIATlOlFQBNGINUBS

TASK 4.1-2IDENTIFY SECONDARY AND CUSTOMERS DISTRIBUTION

EQUIPMENTPROCEDUREl.2.3.

Identify and state the purpose of a secondary distribution transformer.Identify and state the purpose of a LV panel.Identify and state the purpose of metering instruments inside the LV panel.Identify and state the purpose of incoming and outgoingcables for the LVpanel.Identify and state the purpose of a Mini-pillar.

4.5.6. Identify and state the purpose of incoming and outgoing cables for the Mini-

pillar.7.8.

Identify and state the purpose of a consumer'spanel with KWHmeters.Identify and state the purpose of a consumer's panel with KWH meters andCurrent Transformers.

240