Dear Expert,

Please confirm could I use 3UA overload relay instead of 3RU overload relay in below Star -Delta Feeder power Conf..

If Yes then please tell me 3UA oveload equivalent part no. for 3RU2156-5BB10-8K.

Hello,

You can replace 3RU by 3UA. If you want to retain 3RT contactors as it is, you need to go for independent mounting CT operated overload relay i.e. by 3UA6230-5A overload relay. 

HTH