Sinamics S120 hoding brake issue

[glavanov 40]

Hello, everyone,

 

Drive: S120 with CU310-2 PN

Safe brake module: 6SL3252-0BB01-0AA0

Servo motor: 1fk7032-5ak71-1vv3-z

 

 

After 5 years of trouble-free operation: Alarm 7930 - Brake control error[10]

When we power up the system the drive initialisation is done and RDY and COM leds are solid green.

When positioning command is applyed the RDY led starts flashing red 2Hz.

With machine power off and brake coil disconnected from the safe brake relay module we apply 24V DC on the coil for short preiod of time few times to see if the brake works and it does.

We can hear clear klicking sound and the motor shaft is free when applying voltage on the brake coil.

After this operation the system works with no issue for 5-10 days and then again Alarm 7930

Mainly the motor wont move at all and brake holding, but some times during machine operation in state when the motor should stay still and holdin with brake it can moved by hand freely... the brake not holding.

My guess is that the brake is mechanically worn and stuck in the hold position, but sometimes it also gets stuck in the open position.

 

Is there a spare part for the holding brake or the motor must be replaced? No info in manuals...

Shall we look for the problem elsewhere?

Thank you in advance and best regards.

[glavanov 40]

It turned out to be a bad brake coil, but I didn't catch it until got it off the brake.
With a slight application of axial pressure on the coil ring resistance becomes OL.