Star delta testing help needed

[Kj14]

Hi I need some help I haven't work on star delta motors since my 1st year apprenticeship. How do you test the motor from the panel i.e check that the windings are balanced?

Any help much appreciated

 

[telectrix]

you could clamp each phase. see if each was equal current.

 

[Andy-1960]

Depending on the type of load you may find doing a current test on each phase does not always give the answer you may expect. It may be fine on a load such as a fan, but I have a customer that manufactures compressors and we always get out of balance current readings.

Testing in the panel across each set of windings with a good quaility meter should give a matching resistance across all three windings, so test between U1 & U2, V1 & V2, W1 & W2. Then megger test each winding to earth.

 

[PEG]

Hi,depending on constraints,if it was the motor i was wanting to test,i would not include the wiring from panel to motor. Check as described,but at disconnected motor.

This way,any troubling readings are the motor,and not any included part of the connections.

 

[Andy-1960]

Hi,depending on constraints,if it was the motor i was wanting to test,i would not include the wiring from panel to motor. Check as described,but at disconnected motor.

This way,any troubling readings are the motor,and not any included part of the connections.

Testing at the motor with it disconnected would always be my preference, but the OP did ask how to test from the panel so I assumed there were constraints.

 

[Pete999]

Hi I need some help I haven't work on star delta motors since my 1st year apprenticeship. How do you test the motor from the panel i.e check that the windings are balanced?

Any help much appreciated

No such animal as a Star Delta Motor, it's the method of starting that Star Deltahttps://www.youtube.com/watch?v=KsS1v_i2YtU
Best way to check the Windings would be to disconnect the 6 leads at the Motor terminal box, make sure you mark the leads, to avoid malfunctions

 

[PEG]

No such animal as a Star Delta Motor, it's the method of starting that Star Deltahttps://www.youtube.com/watch?v=KsS1v_i2YtU
Best way to check the Windings would be to disconnect the 6 leads at the Motor terminal box, make sure you mark the leads, to avoid malfunctions

...Like that massive circular saw,not cutting as well as previously...

 

[Andy5678]

What is the purpose of the test, maintenance or do you suspect a fault?

 

[Kj14]

The motors getting hot and tripping out Ive insulation resistance tested and that's fine, just want to check the motor is balanced. Need to rule out electrical fault before fitters will look it

 

[Andy5678]

Can you turn the rotor to make sure it turns free and smooth, is there any noises coming from it when it's on, if there's a belt on it is that ok and tight enough. Also check if the overload is set properly

 

[Andy-1960]

Is it changing from star to delta?

 

[PEG]

Perhaps,most importantly of all,what is the motor driving?

 

[mickfred]

Won't be the starter , most likely bearing gone , damaged fan or belt too tight .

 

[Andy-1960]

Won't be the starter , most likely bearing gone , damaged fan or belt too tight .

How can you say it's not the starter? I have seen motors that have been stuck in star either because of a failed timer or even a welded star contactor and boy does the motor run hot!

 

[mickfred]

BECAUSE I SAY ITS NOT ( please don't be the starter )