What is the d/f between DOL & star delta starter & automatic
star delta starter?

Answers were Sorted based on User's Feedback



What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / prakash

A DOL starter connects the motor terminals directly to the
power supply. Hence, the motor is subjected to the full
voltage of the power supply. Consequently, high starting
current flows through the motor. This type of starting is
suitable for small motors below 5 hp (3.75 kW). Reduced-
voltage starters are employed with motors above 5 hp.
Although DOL motor starters are available for motors less
than 150 kW on 400 V and for motors less than 1 MW on 6.6
kV. Supply reliability and reserve power generation
dictates the use of reduced voltage or not

To reduce the starting current of an induction motor the
voltage across the motor need to be reduced. This can be
done by autotransformer starter, star-delta starter or
resistor starter. Now-a-days VVVF drive used extensively
for speed control serves this purpose also.

Is This Answer Correct ?    492 Yes 65 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / niranajn

in dol starte the motor is directly fed from the line and
in star delta starter ther motor is started initially from
star and later during running from delta

Is This Answer Correct ?    348 Yes 49 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / suresh pulipati

In case of Star Delta starter the motor intially will run
in star connection and when 80% of rated speed picks, the
motor change over to delta connection. With this star delta
connection we are able to reduce starting current by 1/3 of
DOL starting current and starting torque also.

Is This Answer Correct ?    226 Yes 33 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / cool

Whenever you start a big heavy electric motor, you need to
start it slowly to prevent the rotor overheating and
drawing an enormous current. When the windings of a 3-phase
motor are connected in STAR the current is reduced to only
root three of the normal running current that is taken when
it is connected in DELTA.

Is This Answer Correct ?    141 Yes 19 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / ankur mishra(moradabad)

In DOL starter full line voltage is fed to motor which will
start motor with a shock, it also draws very high current
than rated current(around 6 times), but if we use star-
delta starter , the motor starts as a star connection later
which is converted in to delta.
using star connection the line voltage is devided in two
phase voltages, also impedence is also increased due to two
star windings which result in low starting current and low
torque which will prevent motor to run with shock.
another difference is DOL starting takes less time while
star-delta takes more time to run at rated speed.

Is This Answer Correct ?    91 Yes 13 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / honey

in induction motor the torque is propotional to squre of
supply voltage in case of dol the motor directly connected
to supply so torque is more while in star delta the motor
is firstly connected to star hence voltage is reduced
torque will be less and when motor reaches its 80% of speed
it connects with delta with the help of timer then full
voltage is supplied hence less rating motor should be
started with dol but for high rating it should be with star
delta

Is This Answer Correct ?    58 Yes 8 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / dipanshu singh

in dol motor is supplied full line voltage hence torque
will be more, whereas in star delta the voltage is reduced
by root 3 times hence torque reduced

Is This Answer Correct ?    51 Yes 15 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / vasu.p

in dol starter the motor is directly fed from the line and
in star delta starter then motor is started initially from
star and later during running from delta

Is This Answer Correct ?    43 Yes 7 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / electo man

To the point, when motor starts using DOL it takes 6 times
its rated current to just start. while in Star-Delta
starter its starting current reduces to one by root three.

Is This Answer Correct ?    47 Yes 18 No

What is the d/f between DOL & star delta starter & automatic star delta starter?..

Answer / rajendra mallick

In a DOL starter motor terminals is directly connected to
starter such that initially a very high starting current is
feed to drive the motor.Dol starter is used for small
motors below 5hp because of high starting current may
damage motor winding. Dol starter using for large motor
using star delta connection,first motor run on star
connection mode upto 80% which provide low starting current
and low torque initally and after getting maximum torgue
motor operates on delta mode with high torgue.

Is This Answer Correct ?    25 Yes 6 No

Post New Answer

More Electrical Engineering Interview Questions

I've heard that most of the substations are rated in multiples of 1.11 because of form factor.What is form factor?

3 Answers  


why table fans rotate clockwise .while ceiling in anti clockwise?

4 Answers  


arrange to send solved question and answer its easy to study and understand the thing, because of Exam is to be conducted shortly

1 Answers  


explain all the classes with example

0 Answers  


why transformer rating is in KVA?

4 Answers   ABB,






How does ELCB work when exist earth foult? and How does RCCB work when exist earth foult?

1 Answers  


Differnce between negative Pahse SequenceFunction and unbalance Function?

0 Answers   Atsco, LMW Lakshmi Machine Works Limited,


A circuit breaker on detecting fault will a. Open b. Close c. Open and trigger the alarm

2 Answers  


what is the minimum (Common factor) insulatin resistance of the following a, 4mm sq wire b, cable from 50 mm sq to 800mm sq

0 Answers  


While testing the value of the resistance for the earthing rod, two auxillary rods are connected to the earthing tester.What is the working function of a earth tester?

0 Answers  


wchich motor we are using in mixer?

4 Answers  


we are operationing 3NOs 800 Kva generators by singronyus.specialey evening time our panel trip. the panel showing generator earth fault

4 Answers   RRB,


Categories
  • Civil Engineering Interview Questions Civil Engineering (5084)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4451)
  • Electrical Engineering Interview Questions Electrical Engineering (16631)
  • Electronics Communications Interview Questions Electronics Communications (3918)
  • Chemical Engineering Interview Questions Chemical Engineering (1094)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (239)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (259)
  • Instrumentation Interview Questions Instrumentation (3014)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (124)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (25)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1379)