Question re: need for line side contactor for an Automation Direct GS20 VFD?

[ControlSysNick]

I'm using an Automation Direct GS20 VFD for the first time and I have a question for the Automation Direct gurus regarding the recommendation of a contactor on the incoming AC line power. According to the manual:

"The addition of a magnetic contactor (MC) in the AC line power input wiring is recommended to turn off power quickly and reduce the possibility of malfunction if the protection function of the GS20(X) AC drive is activated.".

I intend to use the STO function with the E-Stop and this application does not require cutting the power to the drive in an E-Stop situation.

From what the manual says, the purpose of this line-side contactor is to protect the drive if the "protection function of the GS20(X) AC drive is activated.".

According to the manual, the protective function is activated in an overload situation. Would it not be enough to monitor a relay on the the drive for an overload condition and just turn off the run signal if an overload occurred? Or do you always have contactor on the 3-phase AC line power ahead of the drive?

 

[chud]

I really dont like putting line contactors before the drive. I have seen many drives fail because power is removed the whole time especially while running.
We use magnetic circuit breakers which gives a point to isolate and also protects against short circuits on the drive. For me the drive should handle the load side by itself

 

[ControlSysNick]

Hi Chud,

Thanks replying.

Like you, I think the drive should be able to handle the overload situation gracefully and it shouldn't be necessary to cut power on the line side.

However, the manual appears to suggest that it may be necessary. I've attached a screen grab from the Automation Direct GS20 Drive manual.

I'm inclined to interlock the RUN signal to the drive and not install the line side contactor and I think it will be fine. However, as I'm new to the Automation Direct GS20 drives, I was wondering what the folks that use and know these drives would do. Do you use these drives without the line-side contactor and have no problems?

Thanks again!

Nick