problem inverter motor speed controller

Dear Friends.

I have a problem inverter motor speed controller.we are using inverter motor speed controller for controlling 15KW/380VAC/3P motor for plastic bag manufacturing plant.inverter is Toshiba VF-S9.problem is machine run after 8 to18 hours main power distribution panel RCB star to trip frequently.after 15 minute when we start machine again we can use machine 4-5 hours and again start to trip RCB.we are using separate RCBs for each machine so we make correct all the machine ground fault problem but still we are facing this problem.our RCB data is100ma 40A 4 pole.so PL help how to eliminate this problem.thanks.

Regards.
M.kuruppu.

That sounds like a temperatue problem. Could be a rise in temperatur so the isolation of some wires (in the stator) changes its isolation charakteristics and a leakage current trips the RCDs. Only a idea... Maybe have a look on this

Dear Ulf Kirchner.

Thanks for your reply.i will check what you have told things.this machine run without stop every day.so it could be what you have told temperature problem.anyway thanks.have a nice day for you.

Regards.
M.Kuruppu.