Gope_69 said:Yes it be important when need to switch off your Inverters also when there is Emergency..(i mean through Emergency PB)....
504bloke said:MCB on the Input can isolate the invertor (sized to invertor).
For emergency i would not have the contactor on the input to the invertor but put it on the output.
Glenwhere? said:Surely with all the capacitors inside the vfd, it is better to cut off the output rather than the input. That way you are sure that all stored energy is cut off from the drive. The new danfoss drives do not need the high power removed in emergency. They have a special emergency circuit built in which meets ce directive
Speaking of PowerFlex series, Allen Bradley DOES NOT recommend a contactor on the output side of the VFDs.creativepaper said:My old Ansaldo VFD's had a contactor prior to the drive. I am changing them to Powerflex 700VC drives which have a hardware enable digital input (I kept the contactor as the PLC performs some checks (ensures that the regen unit is fully working, etc) before pulling it in).
My E-Stop (Pilz safety relay) quickly ramps the drive to zero then disables the hardware enable, while the Ansaldo drives would quickly ramp down then remove power to the contactor.
I agree that I would not like to keep cycling the power to a vfd, but for a new installation (multiple drives, regen unit) I think I would use input contactors so the PLC is in control when power can be put to the drives instead of the main switch.
504bloke said:MCB on the Input can isolate the invertor (sized to invertor).
For emergency i would not have the contactor on the input to the invertor but put it on the output.
tragically1969 said:Not according to Mitsubishi you dont, it should be on the input side, end of story.