Problem with Star-Delta Starter

For compressor starting : its required high starting time, so every start 6 times

current passes for longer period-so ultimately it burnt breaker contact or motor

winding.

so for equipment like compressor ( High Inertia ) should use auto transfomer having

70 % voltage setting (Than rated voltage) instead of star-Delta starter

N.L. Modha

nirbhaiy@yahoo.com

Thank you for your advise. Is it because the size of the motor (is there a limit that dictates us to use auto transformer starter) or every compressor has to use auto transformer?

Thank you

dear adhyartha,

I think that Panta gave you good idea about your problem with false starting. If I were you I should buy good soft-starter .

Hi there, in most electrical standards the motors with power like yours must be supplied with high voltage 3.3 or 6.6 Kv, but if we want to run this motors with low voltage the best method is by using power transformer supplied with high voltage and transfer this voltage to low feeding the motor, this method decreasing the current on the starter.

Accurate troubleshooting requires sufficient information. Clearly two of your three phases are drawing more current over time than the original designer anticipated. But where and why this unbalance is happening is your problem. Here are a few possible reasons assuming that you're using a synchronous motor:

1. The centripetal starting switch is not opening for the damper windings found on the rotor. (An unusual approach with a synchronous motor but I am grasping at straws here.) This can happen by:
1. mechanical switch failure (gunk or shorting)
2. Insufficient motor speed from increased mechanical load (it's stuck)
2. Two of the starting windings are wired to the running contacts.
3. The motor originally has a wiring short or something mechanically is nicking some stator windings.

If instead you have an induction motor then these ideas come to mind:

1. start current reducing resistors that are wired in series with the three phases and a centripetal switch failure that is not opening for one phase and thus not removing that resistor and preventing the motor to achieve full speed.
2. You may have a failed capacitor bank that is attempting to supply reactive power to reduce real power draw required for efficient operation.
3. Mechanical damage to stator windings

That's my ideas