Use of VFD with motor with mechanical brake

We are using a Powerflex 70 VFD to drive a Sew Eurodrive motor with a built-in mechanical brake. The brake is powered from the feed to the drive. Any recommendations on VFD parameters to make sure that the VFD supplies enough energy to the drive to ensure that the brake releases before the drive starts to accelerate.

Try using RPM measured from the drive and use a contact from a relay or contactor in series with the brake so that the relay activates only when RPM are less than certain value. When starting, disable same relay by using start command in order to run the motor free.

I would say you need an external supply for the brake.
Simply use a "running" signal from the VFD to power a contactor that releases the brake.

I agree with ojz0r. Use a separate full voltage supply controlled with an external relay for the brake.

I agree with the above posters on separately powering the brake. This is usually done by using the Run/Stop relay output on the VFD.

I've tried about everything trying to trick the brake and drive to keep them from fighting each other but never had success. The problem is that, even at very low voltages and frequencies, the drive can detect that the rotor is locked by the brake. Long before the brake release coil has enough voltage to release the rotor, the VFD has faulted, usually on Overcurrent.

I just did one of these.....SEW has a habit of wiring the brake to an internal point of the motor windings. Be cautious about what voltage your brake is looking for. 600 volt motors typically have a 350 volt brake voltage feeding a rectifier module as an example.

I ended up ordering a 24Vdc brake coil from SEW, as this was the control voltage in my panel.

Soggy Canuck said:

I just did one of these.....SEW has a habit of wiring the brake to an internal point of the motor windings. Be cautious about what voltage your brake is looking for. 600 volt motors typically have a 350 volt brake voltage feeding a rectifier module as an example.

I ended up ordering a 24Vdc brake coil from SEW, as this was the control voltage in my panel.

Click to expand...

The SEW rectifier modules I am familiar with include a timer which drops the voltage to a hold in value once the brake is released. This is presumably the 350V you refer to.
I always use an output on the VFD to control the brake rather than one on the PLC as it too easy for people to do silly things in the PLC programme if they think they can "improve" the performance of a drive. In particular I have seen a tendency to hold the brake off when the motor is not running in stop/start applications. This eventually causes the brake coil to overheat and burn out because there is no cooling from the motor fan. People who would happily do this in the PLC programme seem to be far more reluctant to play with the VFD parameters.

Definitively a separate power source for the brake is the option.