3 phase motor starting prob

[sparkypaul]

Hi just joined the forum,I am not too expierienced with motor installations hoping some one can help me out with what i hope is a minor problem.just connected 2 x 3 phase 15kw motors through star delta starters .first one works fine,second one starter contacters pull in fine and power goes throgh contacter fine but does not start and then delta connection kicks in and motor runs. am i missing something obvious ?? cheers sparkypaul.

 

[Darkwood]

Could be numerous problems but start by dropping off both motor connectiions are wiring the suspect motor to the contactor you know is ok, assuming the motors are the same and the overloads are too, does the motor hum when not starting?

 

[silva.foxx]

Hi just joined the forum,I am not too expierienced with motor installations hoping some one can help me out with what i hope is a minor problem.just connected 2 x 3 phase 15kw motors through star delta starters .first one works fine,second one starter contacters pull in fine and power goes throgh contacter fine but does not start and then delta connection kicks in and motor runs. am i missing something obvious ?? cheers sparkypaul.

Welcome Sparkypaul.

Is the star contactor energising?
Is the star contactor closing?
Is the star connection in tact?

Are the links from the delta to star contactor present and continuous?

Is the motor trying to start in star?

Regards
s.f

 

[welshmadness]

What i normally do if i have a star/delta problem is remove the main fuses in the starter (so no 400v), put the starter into `test`mode which energises the control circuit only. I then ramp up the star/delta changeover timer to about 20seconds. Using a ohmeter, put them across L1 and L2, press the start button and take the star resistance reading across the combination. (L1-L2, L2-L3, L1-L3) all should be equal. When the changeover timer activates, repeat the measurement process again for Delta and again you shauld have a balanced reading. All this test proves is that you dont have an open/dead short between any of the motor windings when its trying to start up.

Make sure if you fitted star/delta manufactured links that they are all tight across the contactors and that any of the links have not gone behind the contactor terminals.

Good luck and keep us posted.

 

[sparkypaul]

Hi thanks to all who took the trouble to try to help,when i went back the next day with a fresh mind,it turned out the manufacturer of the star deta starter had missed out links on one of the contactors.Put them in and hey presto it runs a dream.Again many thanks to all.