3Phase meter reading high 3

[farang1]

I have a customer who had us change his incoming power to 3 phase because the power company was continually having low voltage problems on the phase he was on.
3 phase was installed and distributed 1 phase per floor of his Resturant and bar.

Please be aware our power is 220/380. The power along the street is feeding multiple establishments from 2 transformers at opposit ends of the street and are over 1 km away and the wire feed size is 35 sqmm.

The customer has no low voltage problems now as the phase that had the problem is on a floor with only lights and fans.

My problem is the customer used 1800 kw a month when everything was on single phase, now his new 3 phase meter says he is using over 6000 kw a month. Can the meter be at fault? Load has changed very little since the conversion was made. Any suggestions on what or where the problem may be. The resturant is 2 meters from the Sea also.

Thanks
Farang

 

[jbartos]

Suggestion: There are several possibilities available:
1. Additional load was added.
2. Since there is no low voltage problem, the load is used more often or longer. Therefore, the consumption increased from 1800kWhrs to 6000kWhrs.
3. The original meter was incorrectly measuring the electricity consumption.
4. The new meter is incorrectly measuring electricity consumption.

All loads should be listed, added and the load-time profile established to estimate the electricity consumption alternately. This result should approximately agree with the meter reading.

 

[dpc]

I agree with you that it seems unlikely the load increased that much. You might want to verify the multiplier used for calculation of the meter kW. If the meter is digital, I would suspect a problem in the meter setup and configuration.

 

[busbar]

You may want to divide the most recent billed kWh by hours over the billing period to determine average kW load. If the billing versus calculated quantity diverges widely, it may reveal the error.

 

[MarkBates]

1. Sometimes the load can exceed the rating of the meter.

2. While the volts are lower then the number of units recorded will be fewer.

3. I know of a large National Food Distributor who had a programme in place to reduce the 415v supply at all their sites by tapping the supply transformers down one tap. They expected to save thousands of pounds in electricity costs per year.

Also, some utilities (ie, the one I work for) have the provision at Primary Substations to reduce system load. This is achieved by lowering the 11kV volts by 3% or 6% via telecontrol.

 

[davidbeach]

Lowering voltage to lower load is very load dependant. It works with constant impedance loads, but tends to have the opposite effect on constant kW (constant kVA) loads. Loads such as motors and switch-mode power supplies (computers, electronic ballasts for fluorescent lighting) are going to draw enough current to produce the necessary kW. As voltage goes down, current goes up, and as current goes up the voltage drop in the system also goes up, causing a need for even more current.

 

[GerH]

You mention kW but presumably you mean kWhr.
1800 kWhr/month is an average load of 2.5kW
which seems very small for a restaurant.
6000 kWhr/month is roughly 8 kW average.

Load factor might be 50% i.e. peak to average
ratio.

Look at what is installed and estimate what
the peak and average kW might be.

 

[jre]

It sounds more a metering or multiplier calculation problem to me. Don't discount that the owner may have been undercharged previously, and is now metered correctly. 6000kwh per month for a restaurant seems more feasable than under 2000kwh unless all cooking is gas and the load is only lights and ventilation. What about refrigeration ? Was the load metered to each floor previously, or calculated of a single meter? What has changed since.... longer opening hours, more staff, different seasons( summer/winter)?