motor star delta starter problem
motor star delta starter problem
(OP)
Motor started normally on star connection during delta transition supply protection circuit breaker is tripping.
75 KW Induction motor directly coupled to screw air compressor
Moulded case circuit breaker is rated for 160 Amps thermal & 1600 Amps magnetic protection
ganesan
75 KW Induction motor directly coupled to screw air compressor
Moulded case circuit breaker is rated for 160 Amps thermal & 1600 Amps magnetic protection
ganesan





RE: motor star delta starter problem
This is very common when using those foul things. During the transition the motor is disconnected from the power source. It immediately starts to go out of phase with the source but since it still has its magnetic fields its actually a generator. So what you have in your case is a 75kW generator out of sync with the supply that is now reconnected to the supply at some completely random phase angle. You can get 2x short circuit currents. Every start is a crap-shoot of when the the transition contactor closes.
Wye-Delta starters cause a lot of head scratching - "why did the breaker blow?" - questions.
Keith Cress
kcress - http://www.flaminsystems.com
RE: motor star delta starter problem
A higher efficiency motor which typically has lower impedance will likely have a greater propensity for trips. A compressor that starts, perhaps, dozens of times a day has bad odds.
The delay between shifts can make a large difference in the odds too. Perhaps your contactors have gotten slower in transitioning? Perhaps faster? If your setup has a transition delay timer it could be changing in the direction that causes bigger or more common surges. Your breaker could be going out of calibration. The adjustment screw mechanism changing. It could be getting warmer where your breaker is so now it's tripping a little easier?
I'd switch out to a soft starter. You'll stop shocking your power network and everything else sharing it. All the other stuff is also seeing those occasional voltage blasts and current surges.
Keith Cress
kcress - http://www.flaminsystems.com
RE: motor star delta starter problem
Other advice was offerred to me here, including Jeff's discussion of rolling the leads, etc:
thread237-274161: Wye-delta start – peak current and instantaneous setting
In our case we ended up increasing the instantaneous setting./
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(2B)+(2B)' ?
RE: motor star delta starter problem
Muthu
www.edison.co.in
RE: motor star delta starter problem
RE: motor star delta starter problem
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If we learn from our mistakes I'm getting a great education!
RE: motor star delta starter problem
RE: motor star delta starter problem
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If we learn from our mistakes I'm getting a great education!
RE: motor star delta starter problem
If it is an existing installation, I would check the timer, the contactors, and the compressor for proper function. The breaker itself may also be an issue.
The motor is probably not the problem.
RE: motor star delta starter problem
Muthu
www.edison.co.in