Existing MCC

[Anir]

Hello Members,

We working on a project in San Jose, CA for replacement of old motor-pumps fed from a legacy (Westinghouse) MCC.
Provide New connections for new 125 HP, 460V,3-ph motor-pumps. The existing MCC (480V,3-ph) is > 400' away.
The client wants new ABB ACH550 VFD's (w/ C.B) to control the motor-pumps.
The VFD's cannot be retrofitted into the legacy MCC .

Plan : 400A-3P C.B in (E)MCC* - > Feeder/s (~60') - > VFD -> Feeder/s up-to (E)MCC -> Run new conductors from the VFD (>400') through the (E)MCC to go through the existing U.G conduits to connect to the new motor-pumps (thru Disconnect).
* After demo out the old starter disconnects..

(needless to say the client is not keen on any expensive/elaborate construction).

Questions :
1. Can we use (E)MCC to run conductors through it into existing conduit/s ? What are the Code considerations in this kind of install ?
2. If we go with a VFD (w/fused-disconnect) - Can the 400A-3P C.B at the MCC provide the protection for the downstream ?
OR, a fused-disconnect switch at MCC and the VFD (w/C.B) will be a better option ?
3. Any other considerations or code issues that can be foreseen cropping up during this installation ?

Thank you for your time & effort.

Best Regards

 

[Jraef]

Hello Members,

We working on a project in San Jose, CA for replacement of old motor-pumps fed from a legacy (Westinghouse) MCC.
Provide New connections for new 125 HP, 460V,3-ph motor-pumps. The existing MCC (480V,3-ph) is > 400' away.
The client wants new ABB ACH550 VFD's (w/ C.B) to control the motor-pumps.
The VFD's cannot be retrofitted into the legacy MCC .

Plan : 400A-3P C.B in (E)MCC* - > Feeder/s (~60') - > VFD -> Feeder/s up-to (E)MCC -> Run new conductors from the VFD (>400') through the (E)MCC to go through the existing U.G conduits to connect to the new motor-pumps (thru Disconnect).
* After demo out the old starter disconnects..

(needless to say the client is not keen on any expensive/elaborate construction).

Questions :
1. Can we use (E)MCC to run conductors through it into existing conduit/s ? What are the Code considerations in this kind of install ?
2. If we go with a VFD (w/fused-disconnect) - Can the 400A-3P C.B at the MCC provide the protection for the downstream ?
OR, a fused-disconnect switch at MCC and the VFD (w/C.B) will be a better option ?
3. Any other considerations or code issues that can be foreseen cropping up during this installation ?

Thank you for your time & effort.

Best Regards

What's in the MCC now? Starters? If so, you cannot use the MCP breakers that were part of the old starters as feeders, you would need to replace them with real thermal-mag breakers. But once you do that, you are fine with using them to feed the VFDs.

You would only need another OCPD at the VFD if the VFD requires a specific fuse or circuit breaker to get it's SCCR (Short Circuit Current Rating), which is very possible. That's something that ABB should be able to tell you. If it is OK to use any breaker, and 400A is within the maximum allowable for that drive, then you can use a non-fused disconnect at the drive, you do not need to duplicate the OCPD. But again, ABB will have to tell you what size OCPD that drive needs.

 

[Anir]

What's in the MCC now? Starters? If so, you cannot use the MCP breakers that were part of the old starters as feeders, you would need to replace them with real thermal-mag breakers. But once you do that, you are fine with using them to feed the VFDs.

You would only need another OCPD at the VFD if the VFD requires a specific fuse or circuit breaker to get it's SCCR (Short Circuit Current Rating), which is very possible. That's something that ABB should be able to tell you. If it is OK to use any breaker, and 400A is within the maximum allowable for that drive, then you can use a non-fused disconnect at the drive, you do not need to duplicate the OCPD. But again, ABB will have to tell you what size OCPD that drive needs.

Thank you for the answers..

Can you also please let me know the answers for the Questions 1,2,3..

Thanks

 

[Jraef]

Thank you for the answers..

Can you also please let me know the answers for the Questions 1,2,3..

Thanks

Huh... I thought I did...

1. It depends on what you have in there now.
2. You would only need another OCPD at the VFD if the VFD requires a specific fuse or circuit breaker to get it's SCCR (Short Circuit Current Rating), which is very possible. That's something that ABB should be able to tell you. If it is OK to use any breaker, and 400A is within the maximum allowable for that drive, then you can use a non-fused disconnect at the drive, you do not need to duplicate the OCPD. But again, ABB will have to tell you what size OCPD that drive needs.
3. No idea, I'm not there to see it, but in general this is something that is done all the time. If you follow what I said, you should be good to go.

If they are willing to drop one "B" off of the end of their preferred brand, I would be willing to come out and take a look with you. If not, call their favorite brand guys (he says, knowing it will not likely do much good...)