EzTrak + VFD help

The hookup described in post #4 may work with that vfd but could cause failure with other VFDs- some units are more rugged than others
Most manufacturers say to always connect the VFD output directly to the motor, no switches or contacts in between
Opening the motor circuit with power applied causes severe voltage spikes which may damage the VFD output stage
 
If running in sensorless vector it would most likely trigger a fault code if the motor is disconnected while running, you also loose the effects of controlled acceleration and deceleration. It can be done if the VFD is significantly upsized (typically 5-10X) and run in straight V/Hz, and in this case it may have worked because the control system and drives are all fed through a transformer which would smooth the AC output, but transformers can overheat and fail if for an input Hz other than they were designed for.

Newer drives are lee likely to fail if a motor is disconnected while running, and it is not uncommon in industry to use a single VFD to drive multiple motors, but they each require a MPCB designed to be used with a VFD and withing a limited carrier frequency. They are there to provide overload protection and not a means as a motor disconnect. There are also specifically designed plugs for disconnecting these motors which are rated as a motor disconnect device should a motor need to be replaced durring operation.
 
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