Variable frequency drives

[benaround]

You can always add inter-lock contacts at the service switch to open the

vfd side at the same time, in case of accidental opening of service switch.

It's far less expensive in the long run.

 

[charlie tuna]

i'll throw a wrench into the gearbox ------ how do you get around exceeding the voltage rating of the disconnect switch??? the output of the drive is above 600 volts!!!!!!!!!!!!!!!!!!!

 

[petersonra]

i'll throw a wrench into the gearbox ------ how do you get around exceeding the voltage rating of the disconnect switch??? the output of the drive is above 600 volts!!!!!!!!!!!!!!!!!!!

how do you get around exceeding the voltage rating of the motor and wiring?

The answer is they are rated in volts RMS I guess.

 

[steve66]

You can always add inter-lock contacts at the service switch to open the

vfd side at the same time, in case of accidental opening of service switch.

It's far less expensive in the long run.

I have always specified a disconnect switch with an extra "early break" contact. Wire this contact to the VFD enable input, and when someone starts to open the disconnect, it shuts off the VFD before the disconnect actually opens.

Mennekes has an option for this on some disconnects: http://www.mennekes.com/products/disconnect/ms.html

 

[don_resqcapt19]

Charlie,

i'll throw a wrench into the gearbox ------ how do you get around exceeding the voltage rating of the disconnect switch??? the output of the drive is above 600 volts!!!!!!!!!!!!!!!!!!!

If that is correct than how can we use standard 480 volt motors and standard 600 volt wire?
Don

 

[benaround]

Steve66,

You would be surprized at how many guys don't spec. that in. Also, most

manafacturers instructions included with the vfd will spec. that in their booklet.

thanks for the link,