Leaking electricity from transformers. - Page 3
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  1. #41
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    We have a facility where they've actually split the load up onto six meters rather than two (one per TX). Apparently it saves on the connection charges. It would be trivial to change back to two meters so presumably there is some cost savings with doing it that way; I haven't seen their power bills.

    On a more lightly-loaded site, getting a bunch of small meters rolled into one saved a few thousand a year.

    It depends on your load characteristics and your retailer's pricing structure(s).

  2. #42
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    Quote Originally Posted by markz528 View Post
    ...............
    ... Worrying about the no load VAR costs of a transformer to me is utter nonsense.
    Unless you are the one paying the bill, and you are getting dinged a lot for low phase angle. It may be significant, or it may not.

    For that mill building, it seems to have been. The transformer VA was something stupid like 1000 times larger than the load, so they were pulling way more VARs than watts, and the added cost was both significant, and not offset by ANY income from the property, IIRC.

  3. #43
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    Quote Originally Posted by JST View Post
    The transformers are drawing kVA at a lousy power factor, possibly as low as 0.1, because there is a lot of VA and likely not much wattage. It is the "magnetizing current" and since it is flowing in an inductor, it is lagging current.

    You will be paying for the wattage, and getting dinged for the bad power factor as well.

    The 8.5A amounts to something around 7 kVA. How big are these transformers? It seems as if they may amount to somewhere around 220 kVA of transformer, possibly a bit more.

    You may be stuck with the one that supplies your 120, which will be the 208 unit. If it is an ongoing issue, you could install a separate smaller unit for 120V only, which would have a cost, but would allow you to shut off the larger transformers when the place is not operating any machines.
    I agree with everything except the absoluteness of getting dinged for poor Power Factor Most utilities in California only ding you for Power Factor as a DEMAND charge, meaning IF you are not using but a fraction of your normal demand, PF becomes irrelevant. When I used to work for a PFC capacitor company (Sprague, before being bought by Eaton), it was frustrating trying to get users here to spend money correcting their poor PF because the utilities rarely cared.

    8.5A at 480V 3 phase x 0.1 PF = 0.7kW, so even at the horrific California power rates, amounts to about $8/month for BOTH transformers in idle... Hard to get excited about that.

    As said earlier, the size of your bill is more likely all of the fixed costs of just being connected at all.

  4. #44
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    I believe i already said this elsewhere, but the 50 cents per kva per month, which is a demand charge only counting kva if it is more than 48% of the kw demand.. Which means they only bill you if <90% pf

    That 50 cents s approximately the life cycle cost of capacitors.

    Your utility may bill you more or less.

  5. #45
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    Quote Originally Posted by Jraef View Post
    ...When I used to work for a PFC capacitor company (Sprague, before being bought by Eaton), ....
    "Don't be vague, ask for Sprague." Or was that before your time with them?

  6. #46
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    Quote Originally Posted by jim rozen View Post
    "Don't be vague, ask for Sprague." Or was that before your time with them?
    Before my time but it was still kicking around on some older literature.


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