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while running, a slip ring induction motor ,it got tripped and found 2 nos power fuses blown out.on inspection rotor winding IR value zero.ie after releasing the brushes. how it happens?. pl ans

when the motor is starting its an induction motor with a squirrel cage

while its getting up to speed the voltage across the slip rings will be very high

there is a field resister shorting the rings this is removed and replaced with dc

with a make before break field application relay

if the dc is applied before the motor is up to near synchronous speed the stator will need to have very high current to accelerate the mass of the machine

sometimes the controls are magnetic

sometimes a centrifugal switch

sometimes a timer

a compressor will have an unloader to minimise load on the motor before the dc is applied

however this is done

if dc is on the field before you get close to operating speed you will blow fuses

if the "failure" happened while running it could be a momentary power interruption or a momentary load interruption

if the controls didnt see it and restart the motor

you can dissect the fuses and see weather you had a short or an overload

or add a bit more detail about the equipment and incident

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What is locked rotor in three phase induction motor?

A motors locked rotor current is the same as the motors starting current. This is the point where the voltage is applied to a non rotating motor, time cycle zero. Because the motor is not rotation and generating a back EMF to oppose the inrush current, the current will go as high as 6 times the running current of the motor.


What happen if we do the 3 phase winding in rotor of induction motor and give the 3 phase supply only stator winding?

This is how an induction motor normally works, hence the name. The supply voltage is connected to the stator winding(s) and a current is induced in the rotor. A synchronous motor, on the other hand, will have current supplied to the rotor through slip rings and brushes. The rotor current is generally supplied as DC though, or else rectified in the rotor.


In induction motor the will the direction of the rotor will be in the direction of the current?

The direction an induction motor will turn depends upon the direction of the rotating field setup by the winding. Remember in AC the direction of the current reverses itself 120 times every second for a 60 hz system. So no it will not turn in the "direction" of the current.


Formula for rotor speed on a cage rotor induction motor?

The formula to calculate the rotor speed (N_r) of a cage rotor induction motor is given by: N_r = (120 * f) / P, where f is the supply frequency in Hz and P is the number of poles in the motor. This formula assumes the motor is running at near synchronous speed and neglects slip.


What causes the current to decrease as an induction motor accelerates?

The current in an induction motor decreases as it accelerates due to reduced rotor impedance and increased back EMF. As the motor speeds up, the rotor reacts with the rotating magnetic field produced by the stator, causing a decrease in the current needed to maintain acceleration. This decrease in current helps to improve the motor's efficiency and reduce energy consumption.

Related Questions

What is the useful of open end winding of induction motor?

Standard induction motor has a closed squirrel cage rotor, where as open ended induction motor has split phase rotor.


What is induction motor?

Induction motor is an AC electric motor which uses electromagnetic induction to induce the electric current in the rotor to produce torque.


Explain starting of a wound rotor induction motor?

explain wound rotor


How do you convert from slip ring motor to induction motor?

short the rotor terminals.


What did mean by standstill in induction motor?

rotor speed = 0


Does induction motor has rotor winding?

Yes, the induction motor has a rotor winding. It is usually one turn, shorted. This is how the magnetic fields generated in the stator induce a current in the rotor, which subsequently generates a torque from the opposing magnetic fields, stator to rotor.


Pull-out torque of induction motor?

The pullout torque is the maximum torque a motor can achieve. Also known as breakdown or peak torque. It occurs at the point where, the increase in the rotor current is exactly balanced by the decrease in the rotor power factor.


What happens if 3 phase supply is given to stator and rotor both in a induction motor?

its impossible to give suppy to rotor of an induction motor,because of it a closed path for circulating currents.


What happens to the rotor speed and rotor current when the mechanical load on an induction motor increases?

rotor speed will decrease....the rotor current wil increase.....


What happen to the rotor speed and rotor current when the mechanical load on an induction motor increases?

rotor speed will decrease....the rotor current wil increase.....


Which motor doesn't have any winding on its rotor?

Squirrel cage induction motors.


What are the different types of induction motors?

DOL(Direct Online starting) Star Delta starting Auto transformer starting Above methods are for squirrel cage induction motor Rotor resistance starting is used for wound rotor or slip ring induction motor