mkgrady
Senior Member
- Location
- Massachusetts
I have a job where I am feeding four VFD motors. I submitted the motor disconnects and they were approved as noted. The note was to confirm that they are provided with auxiliary contacts for the VFD's. In doing some checking around it appears the auxiliary contacts are there to signal the VFD controller to get ready for the motors to be disconnected. I assume the auxiliary contacts open just before the power wires going to the motor. I think this prevents damage to the motor or the controller.
There is nothing in the contract that requires any kind of control wires from the VFD controller to the motor. It just requires the three power wires and an EGC. I don't see how auxiliary contacts are going to be of any use without a pair of control wires between the disconnect and the VFD controller. Do I have this right?
It looks like I will have to spend about $150 for each of the auxiliary contact kits. I'm installing GE 60 amp 3R disconnects. The contact kits cost more than the switch. None of this appears to be required by the contract. I'm assuming there is nothing in the code that would require this.
There is nothing in the contract that requires any kind of control wires from the VFD controller to the motor. It just requires the three power wires and an EGC. I don't see how auxiliary contacts are going to be of any use without a pair of control wires between the disconnect and the VFD controller. Do I have this right?
It looks like I will have to spend about $150 for each of the auxiliary contact kits. I'm installing GE 60 amp 3R disconnects. The contact kits cost more than the switch. None of this appears to be required by the contract. I'm assuming there is nothing in the code that would require this.