# feeders for vfd's in same conduit



## Rollie73 (Sep 19, 2010)

I'd have no problem feeding to a splitter with this conduit and then feeding each VFD from there. Just keep the lines and the loads seperated as usual and don't group up loads from individual VFD's.


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## buddhakii (Jan 13, 2011)

Thanks Rollie. Just trying to verify what I already knew.:thumbsup:


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## running dummy (Mar 19, 2009)

I second what Rollie said. 


And unless JRaef comes on next saying otherwise ill keep believing its ok! :thumbsup:


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## buddhakii (Jan 13, 2011)

running dummy said:


> I second what Rollie said.
> 
> 
> And unless JRaef comes on next saying otherwise ill keep believing its ok! :thumbsup:


Diddo to JRaef. I think he invented the vfd


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## Rollie73 (Sep 19, 2010)

I'm well trained and versed in VFD installation and programming. I was the only installer certified to do start up on ABB's HVAC drives here on Cape Breton Island for about 6 yrs. I think you'll be ok............lol

BTW.......are you using load side or line side reactors on the job??


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## Jlarson (Jun 28, 2009)

You can run the drive line conductors in the same conduit, wireway... whatever all day long.

It's the drive load conductors you don't want to be running in the same raceways.


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## micromind (Aug 11, 2007)

Jlarson said:


> You can run the drive line conductors in the same conduit, wireway... whatever all day long.
> 
> It's the drive load conductors you don't want to be running in the same raceways.


True.

Done it many times.


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## Rollie73 (Sep 19, 2010)

It works fine. I had one crazy instance where I was getting noise back on the line side of the VFD, turned out to be an issue with one of the VFDs, and it was causing some wierd issues with the other drives on the system. Thats why I asked about reactors......they'll filter all that noise away on both the line and the load side of the VFD, while keeping the voltage nice and constant on the line side.


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## JRaef (Mar 23, 2009)

As long as it is steel conduit, I don't see an issue. If it's PVC cnduit there may be some RFI issues that may require RFI filters on the line sides of the drives, but then again, they may be there anyway depending on the brand.


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## buddhakii (Jan 13, 2011)

Rollie73 said:


> I'm well trained and versed in VFD installation and programming. I was the only installer certified to do start up on ABB's HVAC drives here on Cape Breton Island for about 6 yrs. I think you'll be ok............lol
> 
> BTW.......are you using load side or line side reactors on the job??


These are using load side reactors. And yes JRaef, the conductors are run in ARC.


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## LogixElectrician84 (Dec 7, 2012)

Jlarson said:


> You can run the drive line conductors in the same conduit, wireway... whatever all day long.
> 
> It's the drive load conductors you don't want to be running in the same raceways.


That is correct. As a side note, I am pretty sure you can install shielded cable on the load side (shield terminated at inverter) and run the drive load cables together in the same conduit.

Anybody have any objections to that???


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## Jlarson (Jun 28, 2009)

LogixElectrician84 said:


> That is correct. As a side note, I am pretty sure you can install shielded cable on the load side (shield terminated at inverter) and run the drive load cables together in the same conduit.
> 
> Anybody have any objections to that???


You can run multiple drive cables in one conduit for your load sides but special drive cable is a less common install in the US. And it's a pain to pull multiples in conduit even if you oversize. You also need to bond the shield drain at the drive and at the motor.


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## LogixElectrician84 (Dec 7, 2012)

Jlarson said:


> You can run multiple drive cables in one conduit for your load sides but special drive cable is a less common install in the US. And it's a pain to pull multiples in conduit even if you oversize. You also need to bond the shield drain at the drive and at the motor.



So you are saying that the shield needs to be terminated at both ends? Honestly, it's against everything I've been taught because it will make a ground loop and become ineffective?


Also, you are right it becomes a pain to pull, and I don't see it all that often either in the US, but I have seen it none the less, and haven't had any problems with the motors or VFD's that I maintained.


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## Jlarson (Jun 28, 2009)

LogixElectrician84 said:


> So you are saying that the shield needs to be terminated at both ends? Honestly, it's against everything I've been taught because it will make a ground loop and become ineffective?


There is a difference between grounding a signal cable shield and grounding drive cable shield.

With a signal cable the idea is to keep EMI/RFI out and the idea behind only bonding the shield at one end is to prevent a ground loop that could bypass the shield and interfere with the signal anyway. 

With a drive cable the idea behind the shield it to keep the EMI/RFI given off by the drive in and conduct common mode current back to the drives filters. You want shield continuity from the motor all the way back to the drive.


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## JRaef (Mar 23, 2009)

Jlarson said:


> There is a difference between grounding a signal cable shield and grounding drive cable shield.
> 
> With a signal cable the idea is to keep EMI/RFI out and the idea behind only bonding the shield at one end is to prevent a ground loop that could bypass the shield and interfere with the signal anyway.
> 
> With a drive cable the idea behind the shield it to keep the EMI/RFI given off by the drive in and conduct common mode current back to the drives filters. You want shield continuity from the motor all the way back to the drive.


Well stated. It's a VERY common issue. I just recently came across one where the installer grounded both ends of his signal wires, messed with the VFD brains. He had read the part in the manual discussing the POWER cable shields needing to be grounded on both ends, but extended the concept to the control wires. Two separate issues.


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## LogixElectrician84 (Dec 7, 2012)

Jlarson said:


> There is a difference between grounding a signal cable shield and grounding drive cable shield.
> 
> With a signal cable the idea is to keep EMI/RFI out and the idea behind only bonding the shield at one end is to prevent a ground loop that could bypass the shield and interfere with the signal anyway.
> 
> With a drive cable the idea behind the shield it to keep the EMI/RFI given off by the drive in and conduct common mode current back to the drives filters. You want shield continuity from the motor all the way back to the drive.


JRaef and Jlarson,

Good morning. Based off of more research online, it looks like you are both correct. I didn't even know that, and that's exactly why these forums and other electricians are here. No shame in learning something new, thanks for your advice.

Here are some links with more info...

Belden Unarmored VFD Cable Termination Guide --- Page 10

http://www.belden.com/resourcecenter/tools/installguides/upload/VFD_Cable_Termination_Guide.pdf

plctalk.net

http://www.plctalk.net/qanda/archive/index.php/t-3703.html

eng-tips.com

http://www.eng-tips.com/viewthread.cfm?qid=245854

ABB ACS 800 User Manual - Page 46

http://www05.abb.com/global/scot/sc...ile/en_acs800_04_hw_f_scrres_updatenotice.pdf

Lenze AC Tech Screen Clamps - Page 15 (I found this interesting)

http://www.ctiautomation.net/PDF/AC-Tech/AC-Tech-SCF-Drives-Installation-Operation-Manual.pdf


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