I want to make autooff panel when main power resums for 20 kw 3 phase kirlosker Diesel Gen Set.

 

Do you mean you want the power to remain off when power source resumes after an outage etc.?
Max.

 

It can be done with a 415V (3 phase) contactor detecting the Incoming mains supply, and switching the load over to generator when it has a power cut.

 

You have a 20 KW 3 Phase generator which runs on diesel fuel. Since you mention "main power" I assume this is a standby generator so when mains power fails you use the genset. If I were you since a 20 KW genset is not really all that large I would consider just investing in a fully automatic transfer switch. Most are controlled using a small micro-controller and are not too expensive. mains power fails, the genset starts and waits a few seconds, if no mains power the auto transfer happens and things run on the genset. When power returns the auto transfer switch senses it, waits a few seconds and if mains power is stable it transfers back over to mains power. The genset will then run a few more min for cool down and then shutdown. The same company, Kirlosker who makes the genset also makes auto transfer switches, they are popular throughout India. If you want to build it yourself you will need to define in detail exactly what you have and what you want, including the timing functions..

Ron