Drawing- Is this in violation ?

[milmat1]

Attached drawing, study it carefully. It is just a generic drawing and is just to show a concept.
However, this circuit is from a real machine and I wonder if this is in violation.
My concern is with them using the main OCPD for the VFD and also tapping the other motor and control XFMR from the downstream side of that same OCPD. Which is BTW a J-class fused disconnect.

Couldn't attach a PDF so I made it an image..

 

[Eddie702]

I don't see anything to be concerned about.

 

[ptonsparky]

Looks normal. Max Recommended fusing for a VFD can be way higher than what we as ECs would think about. I often used smaller.

 

[zbang]

Assuming everything is sized appropriately, looks OK to me, too.

 

[petersonra]

I see nothing wrong with it conceptually. I would point out that depending on exactly what you have the wires coming off the main fused disc switch might have some issues on how exactly they get terminated. You typically can't connect three wires to the load side of the disconnect.

 

[milmat1]

I see nothing wrong with it conceptually. I would point out that depending on exactly what you have the wires coming off the main fused disc switch might have some issues on how exactly they get terminated. You typically can't connect three wires to the load side of the disconnect.

We usually either have a PDB for termination or the AB 1494U-xxx have multi-port lugs available.

Thanks...

 

[petersonra]

We usually either have a PDB for termination or the AB 1494U-xxx have multi-port lugs available.

Thanks...

Usually my approach as well. However, you still have to be careful about the wire size coming off the pdb or the multi port lugs. Most times only listed down to #14.

I try to avoid pdb because of the low sccr on many of them, plus they take up room, but since you have a main disc with fuses you should be able to get one that is listed at higher SCCR with a specific fuse upstream.

 

[milmat1]

Usually my approach as well. However, you still have to be careful about the wire size coming off the pdb or the multi port lugs. Most times only listed down to #14.

I try to avoid pdb because of the low sccr on many of them, plus they take up room, but since you have a main disc with fuses you should be able to get one that is listed at higher SCCR with a specific fuse upstream.

Yeah, In this case of 200HP drive, it will require two PDB'S due to the 300MCM wire to the VFD, and the AWG14 to the control circuit. Really a difficult application here to break down the wiring and retain safety..

 

[petersonra]

Yeah, In this case of 200HP drive, it will require two PDB'S due to the 300MCM wire to the VFD, and the AWG14 to the control circuit. Really a difficult application here to break down the wiring and retain safety..

Take a look at the lug choices available carefully. A fair number of the lugs are available with a control wiring connection. This is a tapped hole on the side of the lug. All you need is a screw and a ring tongue terminal to hook up smaller loads. Probably could put two or more rings under the screw.