Bulletin 140M current trip settings for a powerflex 70

[sparky64]

I have a 3 phase 3kw motor that is rated at 6.5 amps flc, the motor is controlled by a power flex 70 drive. The drive is protected by a Bulletin 140 mpcb. I have set the parameter for flc in the drive to 6.5 amps, but in order to have discrimination between the drive and the mpcb, what should i set the current trip on the mpcb to, should it be set to the inrush current of the drive, and if so, is there a rule of thumb, or do i have to use the inrush current formula for each seperate drive.

thanks in advance

Sparky

 

[DickDV]

You need to follow the guidelines in the Instruction Manual for the drive. It will specify the input fusing and may specify circuit breaker specs as well.

If there is no separate info on circuit breakers, set your breaker to best equal the behavior of the fuses specified. Keep in mind that the current limiting device is for branch circuit conductor protection primarily. The drive, if properly programmed, will protect itself and the motor rather well without dependence on the upstream fusing.

 

[JohnW]

Don't use MPCBs with the Powerflex 70. In the back of the manual is the correct 140M magnetic only MCB for use with the powerflex 70. Drives generally provide their own thermal current overload protection.