Home Forums General Discussion Technical Questions braking units for ac drives

I had a problem with a Yaskawa braking unit, on an EC controller, with an Omron VVVF drive. In this case, it had nothing to do with the 3 phase input voltage being too high, but rather, the braking unit just would not shut off at all, regardless of the DC bus voltage level. It was just on all the time, even when not running, constantly putting the drive's internal DC bus across the dynamic braking resistors.

That made 'em burn up. Melted the paint on the controller cover, lots of smoke, set off the building fire alarms. Not a good day...