THW,that is my fear and the odds aren't good.
Just to be clear,this is in an MCC and the motor leads t1,t2and t3 have been removed from the VFD output and brought up to the fuse holders in the combination starter effectively making the disconnect the devise that starts the motor.All o/l protection,and the VFD are out of the circuit.The disco is fused at 50a and the motor FLA is 40a
The issues I have with it are

-the lack of O/L protection

-across the line starting of the very large blower wheel that's intended to be soft started.

-the fact that we are a starting a 600v 40a motor by disconnect on a questionable installation.

- the fact that this building has both an automated switch gear that switches the service entrance between two separate grids on voltage loss with secondary emergency generator backup

The new motor is a week old and the VFD fried when we transferred back to normal power from generator after our annual high voltage maintenance shut down on Friday.I did find L2 very lose and burnt on the line side of the equipment disconnect.If they had returned my call I would have informed them that a drive of the same rating for a far less critical motor is sitting within easy reach of the incoming motor leads in the same MCC and it would have taken me all of 5 minutes to pull the leads into the other tub and do it properly.
If we lose power and it happens often the transfer back to normal power from emergency can be very messy as the generator can be anywhere from 0 to 180 degrees out of phase with normal power.Furthermore we do have an in phase monitor to delay the transfer so i can guarantee that motor will take a hit sooner rather then later.
I most likely be the poor SOB that has to replace both the VFD and new motor on the next go round and if big boss figures out what is going on he will want to know why I said nothing.Sadly going up the chain of command is a very risky proposition around here.I guess my real question is,am I making more out of this than I should?



Last edited by frank; 05/05/14 01:20 PM.