- 1.starter -B. Prasad Chartered Engineer
2. Necessity of starter At starting ,the speed of motor is zero
so that the back e.m.f. In the armature is zero. Armature
resistance is so low, if it is connected to power supply directly ;
huge current will pass thru armature. The huge current may damage
the machine, major heat, very high speed in case of DC series
motor. Ia = V/Ra 3. Function of starter Start and stop the motor.
Limit inrush current where necessary. Permit automatic control when
required Protect motor and other connected equipments from over
voltage, no voltage, under voltage, single phasing etc. 4. Motor
Starter Features. Rated by current (amperes) or power (horsepower)
Remote ON/OFF control Motor overload protection Starting and
stopping (electrical life) Plugging and jogging (rapid making and
breaking current) 5. Type of starter forDC Motor Two point starter
for DC series motor Three point starter for shunt motor Four point
starter for compound motor ForAC Motor DOL Starter Star-Delta
Auto-transformer Variable Frequency drive 6. Wiring Diagram of DOL
Starter: 7. MotorStarting Characteristics on DOL Starter: Available
starting current:100%. Peak starting current:6 to 8 Full Load
Current. Peak starting torque:100% 8. Advantages of DOL Starter:
Most Economical and Cheapest Starter Simple to establish, operate
and maintain Simple Control Circuitry Easy to understand and
troubleshoot. It provides 100% torque at the time of starting. Only
one set of cable is required from starter to motor. Motor is
connected in delta at motor terminals. 9. Disadvantages of DOL
Starter: It does not reduce the starting current of the motor. High
Starting Current: Very High Starting Current (Typically 6 to 8
times the FLC of the motor). Mechanically Harsh: Thermal Stress on
the motor, thereby reducing its life. Voltage Dip: There is a big
voltage dip in the electrical installation High starting Torque:
Unnecessary high starting torque, even when not required by the 10.
Suitability DOL is Suitable for: Small water pumps, compressors,
fans and conveyor belts. Motor rating up to 5.5KW DOL is not
suitable for: The peak starting current would result in a serious
voltage drop on the supply system Motor rating above 5.5KW 11. Star
delta starter Most induction motors are started directly on line,
but when very large motors are started that way, they cause a
disturbance of voltage on the supply lines due to large starting
current surges. To limit the starting current surge, large
induction motors are started at reduced voltage and then have full
supply voltage reconnected when they run up to near rotated speed.
12. Star-Delta Connection in transformer 13. Star-Delta Connection
in motor 14. Star delta power circuit 15. Star delta control
circuit 16. MotorStarting Characteristics of Star- Delta Starter:
Available starting current: 33% Full Load Current. Peak starting
current: 1.3 to 2.6 Full Load Current. Peak starting torque: 33%
Full Load Torque. 17. Advantages of Star-Delta starter: The
operation of the star-delta method is simple and rugged It is
relatively cheap compared to other reduced voltage methods. Good
Torque/Current Performance. It draws 2 times starting current of
the full load ampere of the motor connected 18. Disadvantages of
Star-Delta starter: Low Starting Torque, only 33% starting torque
Break In Supply Possible Transients Six Terminal Motor Required
(Delta Connected). It requires 2 set of cables from starter to
motor. The delta of motor is formed in starter and not on motor
terminals. Applications with a load torque higher than 50 % of the
motor rated torque will not be able to start using the start-delta
starter. Low Starting Torque: reduction of the line voltage by a
factor of 1/3 (57.7%) to the motor and the current is reduced to
1/3 of the current at full voltage, but the starting torque is also
reduced 1/3 to 1/5 of the DOL starting torque . 19. Reversing of
Direction 20. Variablefrequencydrive(VFD) A variable -fre q ue ncy
drive (VFD), also termed adjustable-frequency drive, variable speed
drive, AC drive, micro drive or inverter drive is a type of
adjustable-speed drive used in electro-mechanical drive systems. It
co ntro ls AC m o to r spe e d and to rq ue by varying m o to r
input fre q ue ncy and vo ltag e . 21. Principle of VFD Variable
frequency Drive, principle of the same is by regulating the
frequency, we can regulate the speed of drive Example - n=120f/p
Where, n - speed f - frequency p nos. of poles 22. VFD flow diagram
23. VFD 3-phase power conversion 24. Application Cane Carrier
Drive, Feeder Table Drive, Milling Plant Drive, Raw juice Pumps,
Sulphited Juice Pumps, Molasses Pumps, Injection Pumps, Cooling
Tower Pumps and Centrifugals for a Sugar Curing and Chemical Dosing
pump. 25. Auto transformer 26. Circuit and function An
auto-transformer starter makes it possible to start squirrel-cage
induction motors with reduced starting current, as the voltage
across the motor is reduced during starting. In contrast to the
star-delta connection, only three motor leads and terminals are
required. On starting, the motor is connected to the tappings of
the auto-transformer. 27. Starting Characteristics: Motor terminal
voltage less than line voltage (by transformer ratio). Motor
current exceeds line current (by inverse of transformer ratio).
Starting torque is reduced by the square of the terminal voltage.
Applications: Where complete acceleration at reduced amperes is
needed. Where line ampere reduction requirements are severe, and
load torque is not minimal. 28. Difference between DOL/Star delta
/Autotransformer Sr . DOL Starter Stardelta starter Auto
transformer starter 1 Used up to 5 HP Used 5 HP to 20HP Used above
20 HP 2 Does not decrease the starting current Decreases the
starting current by 1/3 times Decreases the starting current as
required 3 It is cheap It is costly It is more costly 4 It connects
directly the motor with supply for starting as well as for running
It connects the motor first in star at the time of starting in
delta for running It connects the motor according to the taping
taken out from the auto transformer 29. Current in Star Delta
(380to 415V) MotorKW Rated phase current-A MCB-A Fuse -A MCCB-A 1.1
1.4-1.75 6 6 6 2.2 2.6-3 10 10 6 3.7 4.3-5.2 16 20 16 5.5 5.8-7 20
25 16 7.5 7.5-9.3 25 32 25 11 11-13.2 32 40 32 15 14.5-18 40 50 50
18.5 17.3-21.3 40 63 50 22 21.3-26.6 63 80 80 30 30-36.5 80 100 80
37 36-42 80 125 100 30. Current in DOL (380-415V motor) MotorKW
Rated line current-A MCB-A Fuse -A MCCB-A 1.1 2.5-3 16 10 6 2.2
4.5-5 16 20 6 3.7 7.5-9 25 25 16 5.5 10-12 32 32 16 7.5 13-16 40 40
25 11 19-23 50 50 32 15 25-31 63 63 50 18.5 30-37 80 80 50 22 37-46
100 100 80 30 52-63 Not used 125 80 31. WIRE/Cable SIZE
International standard wire sizes (IEC 60228) 0.5 mm 0.75 mm 1 mm
1.5 mm 2.5 mm 4 mm 6 mm 10 mm 16 mm 25 mm 35 mm 50 mm 70 mm 95 mm
120 mm 150 mm 185 mm 240 mm 300 mm 400 mm 500 mm 630 mm 800 mm 1000
mm 32. ACT FAST AND INITIATE FIRST . ---- 33. THANK YOU
