VFD wiring enclosure??

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reel-break

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Hello I`m wiring an enclosure for 2 vfd drives for air make up unit on the roof.I currently have 2 50hp 600 vac motors feeding from a Sq D mcc.I have 2 separate 100 amp breakers to each motor. Now my question is My 2 new VFD`s are located in a new panel I built. Can I run the 2 separate feeds from the 2 100amp breakers to the vfd`s in the cabinet? And what code issues are there such as labeling should I be aware of just as it pertains to the 2 separate feeds in the enclosure. All the wiring and such is compliant. Or is this a big no,no and I need to run a single feeder to the encosure and a disconnect there for both the motors.I`m guessing the safest would be the 1 feeder but money wize the 2 separate feeders would be the ticket with labeling of course.I`d appreciate some feed back. Thanks

I have in the enclosure 2 separate 100 amp breakers 2 vfd`s a set of bypass contactors and the mcc is right beside the new enclosure.Hope I covered it.
 
You can run both feeders in the same conduit. Provided the conduit is of sufficient size.
I would run the feeder conduit to a gutter and set two disconnects. You need the disconnect's as your panel is on the roof.
Then run two conduits or flex from the disco's to the VFD panel. Mark each disconnect and breaker with the location of the power source.

You should have included a line reactor (unless the VFD's have one) in that panel for each VFD. You can always add a smaller panel next to the main panel for the reactor.

Since these VFD's are on the roof. I garrantee that you will wish you had included the reactors.

Do not run any signaling cable or control wires with the input or output conductors. Keep the output conductors seperate from each motor in their own conduit or Flex.

I would have a remote reset downstairs if possible. Or you can mount the VFD keypad at main level. The VFD manufacturer has the extension cable for this. I think they can be no longer than 100', but check with manufacturer.
 
"why would the location of the vfds matter one iota"?

Because when they trip out due to power correction caps closing/opening or other line issues he would have to climb up the ladder or stairs everytime to reset the drive.
The reactors are designed to prevent nuisance trips and that is why I recommended them in the panel on the roof and the keypad at the main level.

I don't like climbing, yes, including stairs, unless I have to. Without the reactors, this could be an everyday pain in the butt.
 
John Valdes said:
"why would the location of the vfds matter one iota"?

Because when they trip out due to power correction caps closing/opening or other line issues he would have to climb up the ladder or stairs everytime to reset the drive.
The reactors are designed to prevent nuisance trips and that is why I recommended them in the panel on the roof and the keypad at the main level.

I don't like climbing, yes, including stairs, unless I have to. Without the reactors, this could be an everyday pain in the butt.
Click to expand...

if there are nuisance trips and line reactors prevent them, what difference would it make where the vfds are located?
 
The MCC control center is right beside the new cabinet with the drives and the line reactors included.My question is involved with having more than one disconnect feeding the same cabinet. Is this code and safety compliant.Please give a reference. The vfd cabinet will feed from 2 separate 100 amp breakers with lockable disconnect built together Mcc control center.I guess my main concern is say a plant eletrician turns off vfd 1 and works on vfd 2 and gets shocked or worse. Is this a code compliant method and common practice. My gut tells me run one feeder and 1 disconnect but the eng. dept. have it with 2 separate feeders for economics I guess.Via the 100 amp dico`s are already there. If I buy a 150a a cell for the existing MCC I`m talking several thousand dollars.Thanks
 
reel-break said:
The MCC control center is right beside the new cabinet with the drives and the line reactors included.My question is involved with having more than one disconnect feeding the same cabinet. Is this code and safety compliant.Please give a reference. The vfd cabinet will feed from 2 separate 100 amp breakers with lockable disconnect built together Mcc control center.I guess my main concern is say a plant eletrician turns off vfd 1 and works on vfd 2 and gets shocked or worse. Is this a code compliant method and common practice. My gut tells me run one feeder and 1 disconnect but the eng. dept. have it with 2 separate feeders for economics I guess.Via the 100 amp dico`s are already there. If I buy a 150a a cell for the existing MCC I`m talking several thousand dollars.Thanks
Click to expand...

Especially since they are adjacent to each other, I don't see a serious problem. Put a sign on the VFD enclosure noting there are two sources of power into the cabinet and where to disconnect them.

I do have to suggest that if you are paying several thousand dollars for a 150A disconnect switch for an MCC, you should find a less expensive source.
 
This is a sore subject in many parts of the country....And that it varies from place to place.....

Third Party....NRTL....110.2....110.3(A).....110.3(B)

Around here....Any more than one device in an enclosure is subject to being listed....

Just my 2 cents....
 
Have you ever had to reset a VFD? Would you rather walk over to the keypad and do it, or have to climb up on the roof to do it?

Reactors or not, the drive is going to trip sooner or later. It's the nature of the beast. They trip.

You can climb up to the roof all day if you want. I'm walking over and reseting it at floor level/eye level.
 
John we have several hundred vfd`s and I rarely have to reset one besides this is in an air make up unit inside the building and we have an elevator if that makes you feel better. So there`s no problem with the 2 separate feeds?
 
reel-break said:
Hello I`m wiring an enclosure for 2 vfd drives for air make up unit on the roof.I currently have 2 50hp 600 vac motors feeding from a Sq D mcc.I have 2 separate 100 amp breakers to each motor. Now my question is My 2 new VFD`s are located in a new panel I built. Can I run the 2 separate feeds from the 2 100amp breakers to the vfd`s in the cabinet? And what code issues are there such as labeling should I be aware of just as it pertains to the 2 separate feeds in the enclosure. All the wiring and such is compliant. Or is this a big no,no and I need to run a single feeder to the encosure and a disconnect there for both the motors.I`m guessing the safest would be the 1 feeder but money wize the 2 separate feeders would be the ticket with labeling of course.I`d appreciate some feed back. Thanks

I have in the enclosure 2 separate 100 amp breakers 2 vfd`s a set of bypass contactors and the mcc is right beside the new enclosure.Hope I covered it.
Click to expand...

Interesting way to do this But I believe it has to have a single disconnect..yet I have couple of questions are we in the same MCC just different enclosure? what was the reason for the enclosure if in the mcc? just so you can run bypass relays?
 
reel-break said:
Hello I`m wiring an enclosure for 2 vfd drives for air make up unit on the roof.I currently have 2 50hp 600 vac motors feeding from a Sq D mcc.I have 2 separate 100 amp breakers to each motor. Now my question is My 2 new VFD`s are located in a new panel I built. Can I run the 2 separate feeds from the 2 100amp breakers to the vfd`s in the cabinet? And what code issues are there such as labeling should I be aware of just as it pertains to the 2 separate feeds in the enclosure. All the wiring and such is compliant. Or is this a big no,no and I need to run a single feeder to the encosure and a disconnect there for both the motors.I`m guessing the safest would be the 1 feeder but money wize the 2 separate feeders would be the ticket with labeling of course.I`d appreciate some feed back. Thanks

I have in the enclosure 2 separate 100 amp breakers 2 vfd`s a set of bypass contactors and the mcc is right beside the new enclosure.Hope I covered it.
Click to expand...

If these are ASD chassies be very careful of mounting them in the same enclosure because radiated interference can drive the controls crazy. (The two would be fighting each other.) As you may notice the ASD manufacturer will supply you with recommended fuse data rather than CB info and it has to do with speedy clearence of fault. You may want to independently protect each drive, if you do the tripple cartridge type fuse holder can enable you to disconnect and service the drive in your Level 2PPE:mad:.

If you have two power source, identify it so.

Watch the cable distance from the drive to the motor that you do not exceed the manufacturers recommendation.
 
weressl said:
If these are ASD chassies be very careful of mounting them in the same enclosure because radiated interference can drive the controls crazy. (The two would be fighting each other.) As you may notice the ASD manufacturer will supply you with recommended fuse data rather than CB info and it has to do with speedy clearence of fault. You may want to independently protect each drive, if you do the tripple cartridge type fuse holder can enable you to disconnect and service the drive in your Level 2PPE:mad:.

If you have two power source, identify it so.

Watch the cable distance from the drive to the motor that you do not exceed the manufacturers recommendation.
Click to expand...

Good point on the chassis mount drive. But, correct wire placement and sufficient distance in the cabinet may prove not to be an issue. You will not know until they are operating. Contacting the manufacturer would be helpful. But, he may have NEMA 1 enclosures making this a non issue. I also agree fuses (semiconductor) are better for AC and DC controls. But breakers are listed in all drive manuals as exceptable. You are correct that each control needs it's own seperate protection. One disco on the roof would be fine as long as the inputs are separated and protected somewhere.
It also looks like the control enclosure is right next to the motors so he should be fine there. This is a variable torgue application, hopefully he did not purchase more drive than he needs. But that would not be a concern as far as operation. Just more bang for his buck.
The poster seems knowlegeable. he will be successful, I'm certain.
 
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