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  1. #1
    Join Date
    Aug 2011
    Location
    maryland
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    16

    power factor capacitor

    I had a power factor capacitor blow up on a 460v starter for a trane cvhe. i disconnected both capacitors and the motor seems to be running just fine. is there any issue with just leaving them disconnected and not replacing them? they are strictly accessories , right ?

  2. #2
    Join Date
    Aug 2009
    Location
    Ontario, Canada
    Posts
    59
    You can get them way cheaper at an electrical supplier than through Trane. Just go to your local ABB dealer and take the Cat#.

    You can run without them but they may pay more to run it.

  3. #3
    Join Date
    Aug 2011
    Location
    maryland
    Posts
    16
    thanks will do

  4. #4
    Join Date
    Jul 2007
    Location
    The Hot South
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    1,373
    You can run the chiller without them but the chiller will use more power. They're accessories.

  5. #5
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    880

    Power factor correction capacitors

    post time- The motor operating the centrifugal compressor has a power factor of about .70-.85, that is the volts-amps that are actually being used as compared to the design volt- amps. The actual figure incurs losses due to inductive reactance. The PFCC's put a leading capacitive reactance to counteract these losses and bring your motor power factor up to .95-.99. Unity or a power factor of 1.0 would be detrimental to the motor so we never attempt for a unity reading. Your electrical provider puts penalties on commercial facilities with lower power factor as this a waste of energy that isn't being of beneficial use that they still have to provide to run your equipment. I totally agree with R123, get your applied voltage rating and somewhere on the original PFCC's there should be a KVAR number depending on your actual motor horsepower. Give them these numbers and you should be good to go. Good luck and be safe out there.-Geo: angel:
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  6. #6
    Join Date
    Jul 2007
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    The Hot South
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    1,373
    That's a great explanation George.

  7. #7
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    880

    Thank you

    R-123- Now you've gone and done it, you're making me blush !-Geo
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  8. #8
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,530
    unity power factor correction is actually ok...it is the OVER correction that can be bad.

    if you do decide to replace the capacitors, make sure that you are wiring them up properly. the capacitors should be on the motor side of the contactors...not the power side of the contactors. if you are not sure, contact a qualified chiller technician or electrician.

    i saw a manufacturing plant that had capacitor banks everywhere. they also had a PFCC on the wrong side of the contactors of the chiller. as soon as the chiller shut down, the capacitors were 'correcting' everything else in the building. every once in a while, 'pop' goes a capacitor...sometimes 'BOOM' goes a capacitor.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  9. #9
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    880

    Jayguy ever hear about....

    Jayguy- I try to limit any power corrections to .97-.99 where economically feasible by customers purse strings. When I took class's on this topic we were taught to never go to unity (1.0) or above because of over excitation and over speed. While we are discussing this I have a question for you. Wye-Delta, closed transition starter, PFCC wired to the load side of the 2M (run) contactor. I would think Load side of 1M (starting) contactor would put them online sooner. I have seen them all over a central plant including switch gear way ahead of the starter for each individual chiller. The ironic part was these were either electronic soft starters of VSD Yorks. I tried to explain to the customer that he didn't need PFCC on these units and showed him in the York literature where the factory had said thats a no, no. If you can get a good motor reaction from unity without damage to equipment more power to you, literally.
    -Geo
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  10. #10
    Join Date
    Jul 2001
    Location
    maryland
    Posts
    1,355
    this thread is a good read, one of the best I've read here.
    Saving the world...one service call at a time.

  11. #11
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by ga1279 View Post
    Jayguy- I try to limit any power corrections to .97-.99 where economically feasible by customers purse strings. When I took class's on this topic we were taught to never go to unity (1.0) or above because of over excitation and over speed. While we are discussing this I have a question for you. Wye-Delta, closed transition starter, PFCC wired to the load side of the 2M (run) contactor. I would think Load side of 1M (starting) contactor would put them online sooner. I have seen them all over a central plant including switch gear way ahead of the starter for each individual chiller. The ironic part was these were either electronic soft starters of VSD Yorks. I tried to explain to the customer that he didn't need PFCC on these units and showed him in the York literature where the factory had said thats a no, no. If you can get a good motor reaction from unity without damage to equipment more power to you, literally.
    -Geo
    i guess my point was that unity is OK by definition. if i found a unit running at or near unity, i would not be worried (because i am not liable for it), however, i would not engineer to unity without a very good power quality study...even then, i would still not correct to unity. typically, correcting to 90-95% is what i find stated in most manufacturers manuals.

    as for the wye-delta, i would wire it to the 2M only because during the start up, you may be over-correcting (even if it is only for the few moments before transition).

    PFCC's between the utility and the starter are acceptable (although they are probably not needed) but between the VFD/soft starter and the motor is a very big no-no, however, some people do confuse 'filters' (which have capacitors in them) with PFCC's. this business is getting confusing and fun at the same time. i have learned a ton since i bought my Fluke 435!
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  12. #12
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    880

    PFCC's

    jayguy- That's about the way I size it up, Thanks for thw answer to the 2M question. I had a rather vivid discussion with an electrician concerning this point, he stated that being on the load side of 2M it was always in the circuit. I drew out the circuit in an attempt to explain that it wasn't, well you know the rest- Geo
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  13. #13
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,530
    Quote Originally Posted by ga1279 View Post
    jayguy- That's about the way I size it up, Thanks for thw answer to the 2M question. I had a rather vivid discussion with an electrician concerning this point, he stated that being on the load side of 2M it was always in the circuit. I drew out the circuit in an attempt to explain that it wasn't, well you know the rest- Geo
    i love electricians!

    "whadda you mean 'phase rotation tool'? oh. i think that Jim has one. other than that, i have only heard of them."

    1 phase rotation meter in an electrical contractor company is like 1 manifold set in a HVACR company.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

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