# VFD Control Question?



## tates1882 (Sep 3, 2010)

I have 4 Yaskawa drives that I'm replacing a CH freedom MCC starter with and I'm using a 24vdc control circuit from a energy management system. I should be using the source setting correct? Also what ramp speed would you use to start 2 circulation pumps (5hp each) and 2 sump pumps (7.5hp each)? They are part of a HVAC system, a heat pump exchange system HVAC system for a health lab/storage facility. The sumps are on a led/lag setup controlled from the EMS, I'm just dealing with two control wires. The circulation pumps are on a alternation setup from the EMS.


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## varmit (Apr 19, 2009)

I would install a interposing relay to isolate the two control power sources. Not sure about these particular drives, but on most drives you do not want an alien power source on the digital inputs. Also, you would not want multiple power sources feeding back to the power EMS system, unless the remote power only went through a dry contact output.

On small pumps, i would use the default ramps, usually 5 or 10 seconds, unless there is some problem.


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## MDShunk (Jan 7, 2007)

x2 :thumbsup:


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## tates1882 (Sep 3, 2010)

varmit said:


> I would install a interposing relay to isolate the two control power sources. Not sure about these particular drives, but on most drives you do not want an alien power source on the digital inputs. Also, you would not want multiple power sources feeding back to the power EMS system, unless the remote power only went through a dry contact output.
> 
> On small pumps, i would use the default ramps, usually 5 or 10 seconds, unless there is some problem.


The drives have a setting for using an"outside" power source for control. If I have to use the drives power I don't think just a ice cube relay will have enough current draw for the drives control circuit.


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## JRaef (Mar 23, 2009)

tates1882 said:


> The drives have a setting for using an"outside" power source for control. If I have to use the drives power I don't think just a ice cube relay will have enough current draw for the drives control circuit.


No I think you are misunderstandIng. You would not have the drive power supply control a relay for the input, you would use your external power source to control a relay, then use the VFD's internal control power source to feed its own input *through* the relay dry contact. That way any anomaly on the external power source damages a cheap little ice cube relay, not the expensive drive board. Keep in mind that just because they have a setting allowing it doesn't mean you should, they don't mind if you to kill the board because they get to sell you a replacement.


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## Wirenuting (Sep 12, 2010)

Put a RIB in and you can walk by and see what the function state is.
They work fine & last long time.

http://www.functionaldevices.com/building-automation/


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## tates1882 (Sep 3, 2010)

varmit said:


> I would install a interposing relay to isolate the two control power sources. Not sure about these particular drives, but on most drives you do not want an alien power source on the digital inputs. Also, you would not want multiple power sources feeding back to the power EMS system, unless the remote power only went through a dry contact output.
> 
> On small pumps, i would use the default ramps, usually 5 or 10 seconds, unless there is some problem.





MDShunk said:


> x2 :thumbsup:





JRaef said:


> No I think you are misunderstandIng. You would not have the drive power supply control a relay for the input, you would use your external power source to control a relay, then use the VFD's internal control power source to feed its own input *through* the relay dry contact. That way any anomaly on the external power source damages a cheap little ice cube relay, not the expensive drive board. Keep in mind that just because they have a setting allowing it doesn't mean you should, they don't mind if you to kill the board because they get to sell you a replacement.


I ended up using the relays that had been previously used in the control circuit.
see pic below


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## tates1882 (Sep 3, 2010)

And heres some pics of the project, didn't get to fire the VFD today but I will Monday. Each motor must be switched one at a time.

















We fabricated the mounting plate and are re using the buckets to power the VFD's.


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## MDShunk (Jan 7, 2007)

tates1882 said:


> I ended up using the relays that had been previously used in the control circuit.
> see pic below


Good man.


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## don_resqcapt19 (Jul 18, 2010)

What did you use for the power source for the drives?


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## tates1882 (Sep 3, 2010)

don_resqcapt19 said:


> What did you use for the power source for the drives?


The existing MCC buckets.


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## don_resqcapt19 (Jul 18, 2010)

tates1882 said:


> The existing MCC buckets.


And what type of breaker is in the bucket? Many buckets have motor circuit protectors (instantaneous only) and you are not permitted to use them except as part of a listed combination starter. Some buckets have thermal magnetic breakers and they would be fine to feed the VFDs with.


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## tates1882 (Sep 3, 2010)

don_resqcapt19 said:


> And what type of breaker is in the bucket? Many buckets have motor circuit protectors (instantaneous only) and you are not permitted to use them except as part of a listed combination starter. Some buckets have thermal magnetic breakers and they would be fine to feed the VFDs with.


No breakers, FLN 30 amp fuses.


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## JRaef (Mar 23, 2009)

I'm sure you did a quality job from the looks of it, but how did you route the wires so that they came out of the left side of that MCC? I dont believe that the rear bus bar space is a legal wireway. Did you check in the C-H MCC installation manual? I've never looked in theirs, but it isn't for every other brand of MCC I've ever used. Too late now of course, but for future reference...


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## Wirenuting (Sep 12, 2010)

Looks like he came out the bottom and that's ok. But that top drive is coming out the side of the bucket. 
I know he said its only fused now, but I doubt you can pull the bucket without disconnecting that whole drive.


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## tates1882 (Sep 3, 2010)

JRaef said:


> I'm sure you did a quality job from the looks of it, but how did you route the wires so that they came out of the left side of that MCC? I dont believe that the rear bus bar space is a legal wireway. Did you check in the C-H MCC installation manual? I've never looked in theirs, but it isn't for every other brand of MCC I've ever used. Too late now of course, but for future reference...





Wirenuting said:


> Looks like he came out the bottom and that's ok. But that top drive is coming out the side of the bucket.
> I know he said its only fused now, but I doubt you can pull the bucket without disconnecting that whole drive.


The top two drives come out of the side of the bucket, the buckets can be pulled still, you have to disconnect the driver just like you would have to motor to pull the bucket. I know its sorta ugly but I had several restriction to work within. I really would have like to set a gutter and tap 5 disco's but if "IF and buts were christmas nuts we would be marry all the time."


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## Wirenuting (Sep 12, 2010)

tates1882 said:


> The top two drives come out of the side of the bucket, the buckets can be pulled still, you have to disconnect the driver just like you would have to motor to pull the bucket. I know its sorta ugly but I had several restriction to work within. I really would have like to set a gutter and tap 5 disco's but if "IF and buts were christmas nuts we would be marry all the time."


Marry?
Ahh,, how about we pop a couple of beers and be Merry.. 

Ya it looked like you didn't have much room to work with. Looks good anyway.


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## JRaef (Mar 23, 2009)

tates1882 said:


> The top two drives come out of the side of the bucket, the buckets can be pulled still, you have to disconnect the driver just like you would have to motor to pull the bucket. I know its sorta ugly but I had several restriction to work within. I really would have like to set a gutter and tap 5 disco's but if "IF and buts were christmas nuts we would be marry all the time."


I can appreciate that, sounds like you came up with a good compromise because if it was the direct side, not the back of the side in the vertical bus area, at least it's safer. 

Sorry if I came off sounding critical, it's just that sometimes new electricians see things like this on the surface and think it's OK when they are faced with a similar situation but didn't know the unseen details. Thanks for making it more clear.


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## tates1882 (Sep 3, 2010)

JRaef said:


> I can appreciate that, sounds like you came up with a good compromise because if it was the direct side, not the back of the side in the vertical bus area, at least it's safer.
> 
> Sorry if I came off sounding critical, it's just that sometimes new electricians see things like this on the surface and think it's OK when they are faced with a similar situation but didn't know the unseen details. Thanks for making it more clear.


No worries brother, the reason I posted was to get feed back. Having guys of you, wire nut,mdshunk, and varmit's caliber chime in great. 
I'll get some pics of the whole room and the interior of the buckets on monday.


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## tates1882 (Sep 3, 2010)

The bucket interiors.








The conductors on the bottom of the starters have since been moved over to the drives.









Looking in the door of the room.
Just to the left is the MCC and drives.








The UPS will be relocated here shortly.


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