star delta motor problem

What is tripping, the Overload Relay or the Circuit Breaker?

Check the current settings.

It this is a new connected motor or the existing motor ?

If it is an existing motor, do you have any problem starting it previously?.

We also want to know if you have change the load, for example last time it was to run a small pumps and now you have change the pump slightly bigger and so on....

What is the load this motor connected to?

What is the timer set for the contactor changeover to Delta point. You can see the timer set inside the control panel.

Please let us have these information.

What I believe is that this is a normal starting method of 3-ph A/C motors, since it is still running.

Most of the time this is the problem you need a multy meter to check the continutie of 6 leads mentioned good luck

crm

My dear friend ,

I have this problem before and I'm sure the connection to the the motor in the power circuit has two wires are awapped.

If you need my advice , just swap two wires from delta connection.

Please also see that

1. Change over From Stat To CDelta must happen when currunt in star falls down.

2. Disconnect Cables from Motor terminals & take Trial of Starter keeping all cables at safe distance. If the starter is nottripping then the problem is in formation of Star. This can be in side the starter & even at motor terminals also.

3. Check current when starter falls in Delta, check whether all three phase is taking current or not. If problem in formation of Delta, one of thep hase will not draw current.

First and formost check the polarity of the six leads terminal and set this aside if you have already determine the correct polarity. then check the control circuit on the delta load side contactor trace the connection moving up to the wye loadside contactor up to the line supply side. the change over timer is just a matter of adjustment the required time delay as you wish but should not long than 10 seconds. Probably the problem is on the delta contactor. thats all, good luck.

First and foremost you must determine what is tripping! If it is tripping on Overload, that is a completely different problem that if t is tripping the circuit breaker. Any advice without knowing that is potentially steering you in the wrong direction.

The tripping known that occur during change over from star to delta. it is probably in the wrong connection on the deta side, might be on either one or two winding naturally it will trip the overload relay of delta contactor, since both relay are in series with star relay otherwise it will not start if it wrong polarity in star connection, it is during the change over. if the polarity is wrong during change over, the effect sudden reverse which is contradict and the current will increase tend to trip the relay before the breaker, since the relay has set to smaller current than the breaker which is capable to handle up to 10kampere of minimum rating in a split of second. try to analyze the characteristic between the breaker compare to a relay. and compare this to a trasformer of wrong polarity connection, if you want a more detail, it is not whom you know but what you know.

As pointed out by a number of very intelligent people already the need to check proper rotation and phasing in Delta mode is important. The timing of the drop out of the star connector and the pickup of the delta connector is also critical. Based on one article you want sufficient time for the arc on the start contactor to extinguish prior to picking up the delta connector.

Mr.JRaef is right.

"First and foremost you must determine what is tripping! If it is tripping on Overload, that is a completely different problem that if t is tripping the circuit breaker. Any advice without knowing that is potentially steering you in the wrong direction."

The main problem is that no one know whether the motor is the existing motor that had been in operating previously and suddenly it give your the problems or it is a new installed motor. If it is a existing motor, then all the information given will be misleading to solve the problem.

check the change over time from star to delta,the motor should at least attained 80% of the fullload before change.

ok i also fasing same probs.so do 1 thing cahnge ur relat..u using 10A class relay..right.. so change with 20 A class relay..by usung this relay u change ur tripping time..ok

YOUR PHASE SEQUENCE IS NOT CORRECT.

i agree with most of the answers..the problem which i think so can be with timer which shift the star delta connection.