Initially motor starts with star connection ,after few
timing changes to delta connection, why the motor should
run continously in star connection,it gives high torque &
low current?
Answers were Sorted based on User's Feedback
Answer / madhu
basically in star connection line current is equal to phase
current,it gives high starting torque. after motor reaches
pick up speed we changed to delta.because in delta line
voltage is equal to phase voltage& line current is root 3
times the phase current.if we run in star in running time
the power losses are more due to current is high. thats why
we changed star to delta.
Is This Answer Correct ? | 18 Yes | 3 No |
The purpose of starter is to start the motor and to limit
the starting current.we are starting the motor in y-
connetion during this impedence of two windings put across
the line voltage hence the starting current gettinh
redeuced
but the motor rated capacity (out put torque)can only be
obtained when itis changed to delta connection this time
the voltage is incresed bu 1.732 time to meet the torque
(torque is direct proportion to square of supply voltage .
Is This Answer Correct ? | 7 Yes | 1 No |
Answer / velusamy
There are two reasons
1.To get high starting torque, motor runs at star for
predetermined duration and then changed to delta.
2.If the motor runs continuously , the capacity of the
motor is reduced by root 3 times (Capacity of motor
rating/1.7324) and hence motor will fail if the OL setting
is not reduced to 1.7324times of motor full load current).
Is This Answer Correct ? | 6 Yes | 2 No |
Is it true that in the 3 phase transformer, the limbs of the core are at 45 dgrees to each other. if true, why?
what is a power factor?
0 Answers MPWU Kiribati, Thermo,
what is intermediate switch
please let me know , we have installed two separate motor for fire fighting system 1) 60 hp and 2) 15 hp the load is 74 AMPS and 20 AMPS then tell me the main power cable in Aluminum will be what thickness , the length is 225 mt from the main utility to fire pump house
hi can anyone pls tell me the eee interview core questions asked in l&t
Hello Can I use step up HV transformer 440/4160V as a step down? Thanks Evgeny
Frequency of rotor emf in induction motor is around A same as stator frequency B 50% C 5 % or below D 30%
How much current in 100 kva Transformer HT & LT side
what is T P N bus bar
How to calculate the copper in HT motors if KW, RPM & Voltage is given
0 Answers Control Dynamics, NTPC,
can we measure +,-.zero sequence current ....? if so how can ???
why tertiary winding is used in transformer with diagram?