I've been asked to investigate unexplained power consumption in a public house (bar where they sell alcohol). The meter has been checked and found to be ok. The client says there has been an unexplained increase in the amount of units the pub is using.

I thought I would investigate a number of things such as: investigating any earth leakage (although would have to be a serious problem); measure current used by appliances to see if as nameplate; any water heater/chiller thermostat not working etc.

There is an interesting article on artificial power consumption but I can't see a pub having much of a PF problem. http://www.marcspages.co.uk/pq/index.htm

Does anybody have anyone thoughts on the subject.

EDIT
On second thoughts PF could be a problem and worth considering. Air conditioning, discharge lamps etc. will all add up to substantial proportion of the overall power used especially if heating is not electric.

[This message has been edited by TeesdaleSparkUK (edited 02-04-2006).]

For a start, I would investigate all of the refrigeration units in the building. If one (or more) has a bad compressor with stray current leakage problems or is habitually hard-starting, it would bump up power use a bit.

Are there other buildings attached to this one? Shut off circuits and see if any other persons try to find out why thier power went off!!It is possible someone accidently or deliberately tied into the pub's circuits.

If the increase is not too huge, I'd look into the possibility of a forgotten lamp(s)in some storage area being left on.

I once had an unexplained jump...when I replaced a fridge with a newer one. The new one was "auto defrost", which was one reason it required more power.

Any new appliance can use much more than the unit it replaces. In the 'old days,' when you turned something off, it was off. Today, many appliances (such as TV sets and fluo lamps) achieve their "instant on" by actually continually using some juice to keep the electronics 'on'....it may be only a few watts, but watts add up.

So, I would ask if there were any new appliances.

If the water heater is electric, I'd start looking for leaks. That's one way to really ramp up consumption in a hurry.

I'd also check the thermostats if there are any immersion heaters. In domestic systems the usage is normally low enough that you soon notice either a drastic increase in the temperature from the hot faucet, even if not actually hearing the water start to boil.

In a pub, it might go undetected with maybe one or two people just casually thinking that the water seems hotter than normal.

During my summer job we had a lady complaining her meter spun too fast. It immediately stopped spinning as we unplugged her roughly 15 year old refrigerator and freezer in the kitchen...
Besides, she complained of her meter spinning much faster than the neighbour's. Well, her meter was a 480 revolutions per kWh type and the neighbour's was a 75 rev/kWh...

On the up side we found her apartment didn't have a ground (her ex who is claimed to be an engineer just ignored the incoming red wire when he rewired and claimed there was no ground available), the RCD didn't work at all and on top of this the evil genius managed to run all the neutrals instead of the hots through the single pole breakers... after seeing that we wondered what kind of engineer that guy could have been... my guess was computer sciences...

Texas, where I come from, "Engineers" are the guys who drive trains.

You forgot "Domestic" and "Sanitation" engineers.

I would check the thermostats of the fridges. If a thermostat is blocked, the fridge will consume much more.

Still on fridges; Check for "Short Cycling" & "Continuously Running" Compressors.
Some symptoms:
Lack of Refrigerant; Faulty Control; reduced Air flow on Condeser (eg. blocked filters, brocken fan belt.); Blocked Filter/Dryer; High Temp. in refrig. area eg(Doors not shutting properly, damaged door seals.); Themostat controlling at too low a temp; Leaky Compressor Valves;

Now a couple of good ones..... Air Cooled Condeser operating with low Temp. outside air; Evaporator needs de-frosting.
Now you hire a CCTV for this one which nobody admits to!!...LEAVING COOL ROOM & REFRIGERATOR DOORS OPEN...."because I was too busy to close it!!!"

Good luck!

Good catch, Texas! In my experience, not too many sparkies know enough about kWh meters. I myself didn't know until I started educating myself on the topic a couple of years back.

Do the nameplates of your meters actually read "revolutions per kWh"? Ours bear the rather cryptic abbreviation "Kh" (watthours per revolution). So, your typical modern 240V single-phase residential meter is a 7.2 Kh (7.2 Wh per revolution, or 138.9 revolutions per kWh), but there are older ones out there that are 12, or 3.6. Old 120V meters (extremely rare by now) are typically 1.8 Kh. 3-phase meters can be a higher Kh (20+), and new digital ones are usually 1.

One of ours says both. Rr 138 8/9, and Kh 7.2

So that's what "register ratio" means! I was told Rr stood for "register ratio" but that I didn't have to worry about it. I never made the connection. Yes, this information is on all North American meters (that I know of), albeit in cryptic form. Canadian meters are the same as US meters. It's all one market. (Although, according to www.watthourmeters.com , Canada held on to the single-phase A-base quite awhile longer than we did. Anyone know anything about this?)

Russian meters turn up from time to time on eBay. I've seen them from the '50s to the '90s. The ones from the '50s have the nameplates all in Cyrillic characters and can be difficult for a Westerner to decipher. The ones from the '60s on have the electrical terms in international standards, so the meaning is much clearer. (Everything else is still in Cyrillic.)

These meters have rev/kWh on the dial. North American meters do not. If you know what Kh means, or Rr, you can figure it out. Otherwise, it's a mystery.

[This message has been edited by yaktx (edited 02-06-2006).]

[This message has been edited by yaktx (edited 02-06-2006).]

I have got an old Canadian Sangamo S 3 meter which has an kh ratio of 1 1/3 which equates to 750 rev. kWh.

to work out kh ratio from revs kWh

1 divided by 750 times 1000 = kh.

as classicsat says it works out the same

1 / 138 8/9 * 1000 = 7.2= kh


In New Zealand most meters are expressed in revs / kWh which is according to the British Standards.

some Dutch meters have the constant as C = 600 or 600 omw / kWh.

I have also seen the Russian meters on Ebay, interesting to note that most of the very old meters are 3 dials and only 5 Amps base load. What is mentioned already that on the nameplate the numerals are in Cyrillic, the dial has the normal numerals.

In Egypt in 1986 I saw meters with actual Arabic numerals / symbols on the dial drums as on the nameplate. Perhaps one of our Egyptian friends can sent us a picture from those meters.

Mine is 166-2/3 revs/kWh.

Silly me...I forgot another common cause of sudden jumps in electric bills....

Check all water heater elements for a fault to ground. A small crack in an element will allow a loss of electricity through the plumbing- as well as make sure the heater spends more time "on." This fault can exist for quite some time before either the element completely fails, or the breaker trips.

Pauluk


Has to be a Sangamo S 200.31 or S 200.33

20 - 80 Amps at 240 Volts 50 Hz.

Cheers Ray.

Almost!

Yes, the name plates show a U/kWh figure (Umdrehungen = revolutions).
I just had a look, our two meters are 800U/kWh and 480U/kWh. Another common figure is 75 U/kWh.

Thanks Pauluk

Didn't think of the 2 rate version of the Sangamo series. Most meters in Auckland are off the one rate tariff for single phase supplies.

Thanks for the replies. I've been to the job today.

I found the following problems: a fridge inside the cellar that was been refridgerated; chiller door seal broken; immersion heater on all the time (you get cheap rate electricity at night in the UK); vents blocked in air con units; food parcels blocking fan in walk in freezer; convector heater left on in room which is heated by LPG central heating; recent introduction of clothes dryers where use of washing line was used before.

Although none of these problems would explain the increase as described by the client I suspect that the increase business and attitude of the staff are the most likely causes.

There was a lot of electric equipment been used such as 9 microwave ovens, an oven keeping pre heated food warm, tea urn etc.

TSUK,
I'd go for a Data Logger on the Incoming Mains.
I've used these before to good effect logging Voltage, Current, PF and Max Demand.
They give a real-time "look" at what is happening in a circuit.
Your output is on a laptop.
Is this place spread over 3 Phases, with a Neutral?.
Refrigeration is a constant current once the compressor is started, only thing that would upset that would be if the thermostat was set too low or the contacts were welded shut.
The compressor would go out on high pressure after a time though

I suggested a Data Logger but it was a no go. The client was looking for one specific thing that was causing the problem and he was monitoring the units on the meter every day.

The installation was 2 phases with a nutral (the third fuse at the service head didn't have any tails coming out). One thing I haven't noticed before was the meter was the type with the spinning disk with both phases going into it. I've usually seen a meter on each phase.


[This message has been edited by TeesdaleSparkUK (edited 02-10-2006).]

Oops, a three-phase meter with only two phases connected? Could that unbalanced load cause trouble too?

I've never really thought about the typical 3-ph meters here, but are the voltage coils in them usually connected phase-to-neutral or phase-to-phase?

As long as all the voltage coils are energised the meter will be very accurate.
If one voltage coil is de-energised the voltage flux from the missing phase, its braking effect at light loads, may make the meter go a little faster in the order of around 1 to 1½ %.
This only applies to genuine 3Ø4Wire meters.
e.g. 3x230/400 Volts or 3x120/208 Volts with a Neutral.

Some 3Ø meters have the BØ PT coil wired with 3 wires in (not 100% sure) Scott type connection between the PT coils, so that these can also be used on 3Ø without Neutral as well e.g. 3Ø3Wire or 3Ø4Wire ccts.

In my days in meter calibration I have proved it on the test bench with a 3 phase meter running at 2Ø or even 1Ø. As long the other PT coils are live, the meter will be very accurate to within its class.

In New Zealand when with tariffchanges in the early 1990's, some older pumpsheds were converted from 3Ø to 1Ø it was not always warranted to fit a new 1Ø meter. ( Usage in some of these pumps is sometimes less than 100 kWh / Year). We left the 3 Ø meter on site and put PT jumpers in to the other 2 phases to keep the coils energized and the meter accurate. A lot of these meters were the Sangamo S 301.2 type, 66 2/3 rev kWh,
3 x 10 / 60 Amps, clockdial type

Lots of different meter pics thanks to Ray now posted in the Photos area here:

kWh Meter Types

If that were the case, they wouldn't be using a single 3 phase meter for domestic use here. The first house I lived in, built in 1967, had a single 3 phase meter, so they've been around at least that long. Obviously in a residential situation the current draw on each phase is seldom going to be equal. Older houses here have a separate meter for each phase and the kw/h are merely added together for billing purposes.

Well, I wasn't talking about current draw but about voltage at all. As said, if one voltage coil is not energized the meter will be off.

One other cause of short-cycling and no real cooling is a leak in the refrigerant lines.
or a shortage of gas in the lines altogether.
Until you get some gauges on the equipment, you have no idea what is happening inside the system.
A set of Refrigeration Gauges is like our Volt-meter.
And to a degree a Current meter too.
System Pressure is a big part of Refrigeration.

Well, now I've been out and looked at a few, and they don't say 138 8/9. They say 13 8/9. And there are quite a few out there with the same 7.2 Kh, but a different Rr (27 1/3, or something like that).

So Rr is not the reciprocal of Kh, nor does it have any apparent mathematical ratio thereto. I have no idea what it means.

Funny thing, though. If it did say 138 8/9, that would make sense!

That sounds similar to the 120/208 single-phase "network" service we have in certain urban areas here. Here, that type of service uses a Form 12S meter (2 current coils and 2 120V coils), which looks similar to the more common Form 2S (2 current coils and 1 240V coil).

A meter on each phase... I've only seen that once, in Mexico. It was in the corner of a small restaurant. Exposed knife switches, too!

[This message has been edited by yaktx (edited 02-16-2006).]

yaktx

Rr stands for register ratio, and is not always the correct constant, the way I understand it that it has to do something with the intermediate gears from the register train.
We have Sangamo meters here 3 Ø 40 Amps with Rr of 40 and 80, The meter in both cases was a 80 rev / kWh meter but the pitch of the worm drive was different. In case of the Rr of 40 the pitch was 1 rev of the disc is one cog advance on the register.
In case of the Rr of 80 one rev of the disc advaced 2 cogs on the register.
I have a read up through some of my metering box what the actual definition is.
I will get back to this interesting topic.
Raymond

from "Hand book of Electricity Metering" ninth edition. quoted from text on page 136.

Kh is the number of watthours represented by one revolution of the disc.

Rg The necessary gearing is provided so that the revolutions of the disc will move the first (or right-side) pointer or cylinder one full revolution (360degrees) each time the rotor revolves the number of times equal to ten kilowatt-hours of usage. This is known as gear ratio, or Rg.

Rr The register ratio, known as Rr is the number of revolutions of the wheel which meshes with the pinion or worm on the disc shaft for one revolution of the first dial pointer.

Thanks, RODALCO.

So Rr only has to do with the worm & pinion. Now it makes sense how two meters could have the same Kh but different Rr.