Automatic Cap Banks

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I believe a big problem of our is the Chillers we have almost each building. I was looking on the Chiller unit itself and there are motor nameplates all over it, which one do I use???

I have a model number WSC087LB and its a McQuay. I looked at the control screen and took a pic of it. I attached the picture.

This is one of the Two 480V Chiller Units in the building. Last month our Peak was 720.25 and PF of 85%, looks like we can save a lot at this location.

What is the best way to figure out the Kvar needed on this chiller? What data do I need to get you guys so I can better understand this?

IMAG0517.jpg
 
raiderUM said:
I believe a big problem of our is the Chillers we have almost each building. I was looking on the Chiller unit itself and there are motor nameplates all over it, which one do I use???

I have a model number WSC087LB and its a McQuay. I looked at the control screen and took a pic of it. I attached the picture.

This is one of the Two 480V Chiller Units in the building. Last month our Peak was 720.25 and PF of 85%, looks like we can save a lot at this location.

What is the best way to figure out the Kvar needed on this chiller? What data do I need to get you guys so I can better understand this?

View attachment 7117
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There you go. Take on the bigger ones and you'll probably save big. If "720.25" means "kW", you'll need about 210 kVAr to correct your from 0.85PF to 0.95.
 
Phil Corso said:
Mivey...

Not necessarily just with larger motors. I also have data on a Westinghouse 600 Hp, 4.0kV motor. The INL vs IFL ratio is 15.2 -15,7%. Need a to see it?

Regards, Phil
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I'm sure motors can be specifically designed to have low no-load losses. The question is: what is typical? I have some generic tables around here somewhere but I thought from the discussion that maybe you two might have a large set of actual data we could use as a guide.

Bes offered that in 40+ years of experience that around 20% was about the lowest he had seen and I know he has seen a lot of motors. He also felt it was not typical of the smaller motors he has seen.

With your comments I thought that maybe Bes might have missed some exposure to a different group of common motors and your insight could be illuminating.
 
Mivey...

I've been around longer much longer, and I always have advised those I worked for, and clients I consult for that "typical" can be used when it is clear that damage and the probability of litigation are "unlikely!" (And I've been involved in several law suites! Some as the defendent!)

What's wrong with checking with the motor mfgr? It's a relatively simple thing to do. And if that route is impossible, then its time for a review by a professional!

Regards, Phil Corso

Ps: Regarding PFC, many times reasonable success can be accomplished by raising bus-voltage, but this approach, is not "typical"!
 
Phil Corso said:
Mivey...

I've been around longer much longer,
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Longer that 40 some years in the electrical field?
You must be quite aged.


Phil Corso said:
What's wrong with checking with the motor mfgr? It's a relatively simple thing to do. And if that route is impossible, then its time for a review by a professional!
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FWIW, I am a professional. My background is in power electronics and mostly variable speed drives. In many cases with have to provide guaranteed operating performance at the bid stage of a project. There are serious financial penalties if you don't meet those. Puts you between a rock and a hard place - be safe and conservative and you lose the job to someone who quotes better performance or be bold and risk getting clobbered with penalties. It has fallen to me to do the calculations and, I'm pleased to say that to date, we have not missed the target once in all those years.
Some of the figures I've included have been used for such calculations.
Here's another from a pumping station application were we installed three 625kW drives which is more in the range being discussed here.
On fixed speed FLC is 647A and 205A at no load.
And another for a 500kW, 660V motor, also for a pumping station
FLC is 524A, NLC is 186A
Real motors. Real data.
And I could cite many more.

Do you now see where I got the 30% from?

Phil Corso said:
Ps: Regarding PFC, many times reasonable success can be accomplished by raising bus-voltage, but this approach, is not "typical"!
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Actually, many variable speed drives have the facility to reduce the voltage on lighter loads to reduce the losses by reducing stator current which, of course, means improved power factor.
 
topgone said:
There you go. Take on the bigger ones and you'll probably save big. If "720.25" means "kW", you'll need about 210 kVAr to correct your from 0.85PF to 0.95.
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Raiderum
Take a look at this sequence: 1, 2, 4, 8, 16...... If we add together the terms, any number up to that sum can be represented as a sum of those terms.
So if the capacitor sizes are chosen that way for automatic power factor compensation, power factor compensation is closest and no hunting problem for contactors.
 
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Besoeker said:
Do you now see where I got the 30% from?
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You got the 30% from the new category of energy efficient motors in which slip is smaller and air gap is larger than in conventional motors?
 
Besoeker...

1) Re: NL/FL Ratio:
Will the motor performance data I sent you clear up doubts you may have had regarding my veracity?

2) Re: My age:
Yes! Quite! And 22-jun I turned 62; was 63 in May! I tell grandkids in 20 years we will be the same age!

Regards, Phil Corso
 
Phil Corso said:
Besoeker....

Yesterday, @ 4:11pm edt, I sent ASEA "Official" data to an e-mail I thought was from you! Address started with "nm.."

Phil
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OK. Got it thanks.
There are four measured current values listed for the no load curve for each of the voltages for which the test was run including that at nominal voltage.
I could make a guess at what the four current values might mean but rather than guessing, perhaps you would be good enough to explain what actually was measured.
 
Besoeker said:
OK. Got it thanks.
There are four measured current values listed for the no load curve for each of the voltages for which the test was run including that at nominal voltage.
I could make a guess at what the four current values might mean but rather than guessing, perhaps you would be good enough to explain what actually was measured.
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What were the values and how were they labeled?
 
topgone said:
There you go. Take on the bigger ones and you'll probably save big. If "720.25" means "kW", you'll need about 210 kVAr to correct your from 0.85PF to 0.95.
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720.25 is my peak, so if I am not mistaken that is my KVA. My KW would be 612 and I would need 180 kVar, with a savings of $863 for the month
 
raiderUM said:
720.25 is my peak, so if I am not mistaken that is my KVA. My KW would be 612 and I would need 180 kVar, with a savings of $863 for the month
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No disagreement with your calculations at 720kVA.
But you might need also to consider minimum kVA to avoid the possibility of over correcting and getting a leading power factor.
 
Besoeker said:
But you might need also to consider minimum kVA to avoid the possibility of over correcting and getting a leading power factor.
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That is why he is proposing to use an automatic power factor correction arrangement. I think you did not read the thread in full.
 
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