Posted by danny burstein on January 15, 2007, 2:51 am
i[ regarding a garage wit about 35 kw of HP Sodium demand ]
>>If I ask the utilty if the wave forms are screwing
>>up the meter readings, would they laugh me out
>>of the room? Is there any valid issue here?
>No, they won't laugh but there isn't an issue here. That kind of
>service is demand metered and if an electronic meter is involved, also
>power factor metered. If it's a mechanical meter then most likely the
>utility either measured the power factor or was involved in approving
>the building's electrical design. Utilities charge a penalty for low
>PF. Harmonic energy shows up as out of phase current and registers as
>low PF. If there was a significant problem it would show up on your
>power bill.
Given that the fixtures were installed over ten years ago,
and were probably lowest bidder.... I'd guess they'd probably
be lower PF than today's stuff.
Unfortunately, while I could physically do a bit of
checking myself, the facility would frown on my clipping
apart wires. (I'm going to try to get a look at the
bill and see what the demand and the kw-hr numbers
are... since I can visually count the fixtures and
calculate what the numbers should be, I'd be able to
at leasst catch a gross difference).
So... is there any downside to politely asking the
utility to take a look?
Thanks again for your help.
--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]
Posted by Neon John on January 16, 2007, 5:01 am
On Mon, 15 Jan 2007 07:51:57 +0000 (UTC), danny burstein
>Given that the fixtures were installed over ten years ago,
>and were probably lowest bidder.... I'd guess they'd probably
>be lower PF than today's stuff.
>Unfortunately, while I could physically do a bit of
>checking myself, the facility would frown on my clipping
>apart wires. (I'm going to try to get a look at the
>bill and see what the demand and the kw-hr numbers
>are... since I can visually count the fixtures and
>calculate what the numbers should be, I'd be able to
>at leasst catch a gross difference).
>So... is there any downside to politely asking the
>utility to take a look?
>Thanks again for your help.
You're welcome.
The only downside would be if these really are low PF fixtures and/or
generators of harmonic energy and the utility hasn't discovered it yet
then "help" from the utility might result in additional charges.
The services of a power quality engineering consultant will cost you a
little up front but there is no continuing down side exposure. That's
the route I'd go.
Another option, if you can gain access to the conductors, is to rent a
Fluke or Dranetz power quality analyzer and do the measurement
yourself. Both brands of instruments use clamp-on transducers
(alligator clips for the potential leads) and are completely
non-invasive. They're menu-driven and the accompanying PC software
generates very readable and useful reports. The manuals are tutorials
on power quality. If they'll let you pop the cover on the breaker
panel then you can do the measurements.
Rental outfits such as GE rentals will rent one of these for as little
as a week. Cost should be in the couple-hundred-dollar range, I'd
think.
John
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain
Posted by Solar Flare on January 16, 2007, 5:43 pm
...and the Fluke unit just got all the upgrades in the new model we
asked for after out completely failed demo two years ago. It is an
awesome unit now.
> On Mon, 15 Jan 2007 07:51:57 +0000 (UTC), danny burstein
>>Given that the fixtures were installed over ten years ago,
>>and were probably lowest bidder.... I'd guess they'd probably
>>be lower PF than today's stuff.
>>
>>Unfortunately, while I could physically do a bit of
>>checking myself, the facility would frown on my clipping
>>apart wires. (I'm going to try to get a look at the
>>bill and see what the demand and the kw-hr numbers
>>are... since I can visually count the fixtures and
>>calculate what the numbers should be, I'd be able to
>>at leasst catch a gross difference).
>>
>>So... is there any downside to politely asking the
>>utility to take a look?
>>
>>Thanks again for your help.
> You're welcome.
> The only downside would be if these really are low PF fixtures
> and/or
> generators of harmonic energy and the utility hasn't discovered it
> yet
> then "help" from the utility might result in additional charges.
> The services of a power quality engineering consultant will cost you
> a
> little up front but there is no continuing down side exposure.
> That's
> the route I'd go.
> Another option, if you can gain access to the conductors, is to rent
> a
> Fluke or Dranetz power quality analyzer and do the measurement
> yourself. Both brands of instruments use clamp-on transducers
> (alligator clips for the potential leads) and are completely
> non-invasive. They're menu-driven and the accompanying PC software
> generates very readable and useful reports. The manuals are
> tutorials
> on power quality. If they'll let you pop the cover on the breaker
> panel then you can do the measurements.
> Rental outfits such as GE rentals will rent one of these for as
> little
> as a week. Cost should be in the couple-hundred-dollar range, I'd
> think.
> John
> ---
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> Cleveland, Occupied TN
> Don't let your schooling interfere with your education-Mark Twain
Posted by Solar Flare on January 15, 2007, 7:54 pm
A little senile there?
When did utilities get involved in the type of load presented when all
the fixtures are UL or CSA approved? For cripes sakes the utilities
are putting in sodium vapour lamps for street lighting everywhere.
When did a harmonic start changing the phase angle of the fundamental
current frequency? Some of the harmonic cycle current lead the
voltage. You need to study up a bit first there.
Do you know how many services are demand metered on power (wattage)
only? This is a lighting load and most utilities can't be bothered
with VAR metering.
You have forgotten, or never knew, the difference between lagging PF
and harmonic distortion.
> On Mon, 15 Jan 2007 00:34:38 +0000 (UTC), danny burstein
>>
>>I've seen lots of discussion about the
>>harmonics and other issues from HID lamps (or
>>more properly, tehir power supplies).
> Unfortunately, a lot of that is pure BS.
>>However, we have a standalone muliti-story garage, which is
>>illuminated 24 hrs/day by about 35 kw of high pressure
>>sodium luminaires (with another 5 kw or so at night) getting
>>fed via 3 phase AC. There's perhaps one or two addiotional
>>kw of demand for some office equipment and (fluorescent)
>>lighting. And a short occassional kw when opening/closing
>>the garage doors.
>>
>>This building is separately metered.
>>
>>If I ask the utilty if the wave forms are screwing
>>up the meter readings, would they laugh me out
>>of the room? Is there any valid issue here?
> No, they won't laugh but there isn't an issue here. That kind of
> service is demand metered and if an electronic meter is involved,
> also
> power factor metered. If it's a mechanical meter then most likely
> the
> utility either measured the power factor or was involved in
> approving
> the building's electrical design. Utilities charge a penalty for low
> PF. Harmonic energy shows up as out of phase current and registers
> as
> low PF. If there was a significant problem it would show up on your
> power bill.
> Low PF/high harmonic HID and fluorescent ballasts are pretty much
> things of the past. The various mandatory efficiency laws combined
> with low PF penalties and in some areas, harmonic energy
> restrictions
> have pretty much taken care of that. A high PF ballast will
> typically
> present a PF of 0.96 or better at its terminals. Low PF ballasts
> are
> still available but nobody specifies or buys them to any significant
> degree.
> John, retired utility engineer
> ---
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> Cleveland, Occupied TN
> Don't let your schooling interfere with your education-Mark Twain
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>>up the meter readings, would they laugh me out
>>of the room? Is there any valid issue here?
>No, they won't laugh but there isn't an issue here. That kind of
>service is demand metered and if an electronic meter is involved, also
>power factor metered. If it's a mechanical meter then most likely the
>utility either measured the power factor or was involved in approving
>the building's electrical design. Utilities charge a penalty for low
>PF. Harmonic energy shows up as out of phase current and registers as
>low PF. If there was a significant problem it would show up on your
>power bill.