Why is it that variation allowed in supply voltage to motors is (+ or -)10 %,

Why is it that variation allowed in supply voltage to
motors is (+ or -)10 %, whereas that in frequency is (+ or -
)5 %

Question Posted / shyamalmandirwala

3 Answers
5639 Views
I also Faced
E-Mail Answers

Answers were Sorted based on User's Feedback

Why is it that variation allowed in supply voltage to motors is (+ or -)10 %, whereas that in freq..

Answer / gajendran.al

Variation in supply voltage to motor affects the torque
produced by the motor and is not affected much with +/- 10%
whereas variation in frequency affects the speed of the
motor. Even 1Hz variation could vary speed by 30 rpm for a
4 pole motor. So variation in frequency is not advisable in
motor
Pl note that increase in supply frequency makes the motor
rotate above rated speed which may cause mechanical failure
of motor.

Is This Answer Correct ?

6 Yes

0 No

Why is it that variation allowed in supply voltage to motors is (+ or -)10 %, whereas that in freq..

Answer / subash

But in motors the rated frequence +or- 5% will be there its
true

Is This Answer Correct ?

0 Yes

0 No

Why is it that variation allowed in supply voltage to motors is (+ or -)10 %, whereas that in freq..

Answer / shriram.....

For the motor we are not using ups power supply

In ups power supply, we can maintain the voltage as well as
frequency.

But we are using raw power for motors in plants.

Eg if I we are using some load. Now I getting 415 volts at
full load if I reduce some load any reasons then voltage
will lightly increase so voltage will not stay constant.

For that reasons operating voltage +/- 10 %

Shriram....

Is This Answer Correct ?

0 Yes

2 No

Post New Answer

More Electrical Engineering Interview Questions

The capacity of the transformer is 20/25 MVA, Ratio is 132/11 KV, Vactor group YNyno. and impedance is 10.07%. As per the calculation the secondary current is 1312.2Amps. The maximum fault current the transformer should sustain is 13.030KA. How many times the transformer should sustain the maximum short circuit current of 13.030KA over a period up 1 Year. The transformer is repaired one & 10 Years old.

1 Answers

how to carried out tan delta test in 11 KV alternator ?

0 Answers

what's float charger and boost charger? why it's used?

2 Answers APCPDCL, PTCL, Rolls Royce, Siemens,

Is it required to lay 2 runs of GI wires along with armoured cables from one power DB Machines of higher rating?

0 Answers

what is the equation of insulating resistance of motor???

1 Answers Birla,

What should be the values of settling time, peak time, steady state error, overshoot, rise time, MPOS (Maximum percent over shoot) to keep the system in transient state, to keep the system in steady state ?

0 Answers

In Power Line Communication (PLC) the wave trap is used to block communication signals from entering neighboring lines. My question is this: Why do they allow for different filtering arrangements on these wave traps? Isn't it always going to be a low pass filter since we want the power frequency to go through, and the comm signal blocked?

0 Answers

what is the VVVFD and?

4 Answers

What difference between ref protection and differential protection ?

0 Answers EPC, INEL Power System Engineers,

How many current ratings of MCB's are in the market? e.g: 1A, 2A, .......upto.

4 Answers

WHAT DO YOU MEAN THE DIFFERENT TYPE OF CURVES OF RELAY LIKE STANDARD INVERSE, VARY INVERSE, NORMAL INVERSE, LONG INVERSE ETC....

0 Answers

Hi all I had applied for the RRB test in the ELECRICAL category. I would be pleased if any of you can sent me previous year question papers. Please forward the question papers to varshashahi@yahoo.com Thanks and regards Varsha

0 Answers

For more Electrical Engineering Interview Questions Click Here