As the Jamaica Public Service moves to replace the very reliable analog (rotating disk) meters with the newer electronic meter, which allows for easier data collection of the power consumption of the customer, there could be “problems” ahead for the customer.
The old rotating disk and dial meter as they are known was built to ANSI C12.1 standard and has recording error of around 4% (i.e. +/- 2). What this really means is that the meter could record anywhere between 2% higher or 2% lower than your actual consumption.
The new electronic electrical meters used for residential customers however are built to ANSI C12.20 and rated at class 0.5 which has an error of only 1% (i.e. +/- 1). While this is good for the utility company it could mean “bad” news for the consumer, simply because its more accurate.
In addition to the above , while the analog meter was only able to measure electricity down to 0.3A (66W) on a 220V supply, these new digital meters are able to measure electricity down to 0.1A (22W). Think of it this way your old meter would allow 3 x 22W fluorescent bulbs to run and would not be able to record this, however with the digital meter only 1 bulb could be on before this new meter will detects its on.
Electromechanical (Analog) metering issues.
As can be seen from the graph below (courtesy of EPRI) the analog meter shows loss of registration over time and this is outside of the intrinsic error of +/- 2% in the design of the meter.
Now if you have a meter for say ten years it could be recording at say 99.2 % of your actual consumption and when the error is added this could be as low as 97.2% of the actual consumption.
These analog meters “slowdown” over time due to aging, dirt, insect and other types of debris resulting in the meter under recording your consumption. Now if you have a meter, which has been under-recording for sometime, you could be in for a shocker when these new and more accurate digital meters are installed.
See this additional graph below again provide by EPRI which shows that in a sampling of over 400,000 meters in the states approx 0.3% of the “population” have meters recording between 10 –20% lower registration that they should i.e. they were recording only 80 –90% of the electricity consumed.
This problem shown here however disappears with the installation of the new electronic meter and therefore the residential customer so affected, sees an immediate increase in not only his consumption but also his bill. ( Between 10 – 20% increase would be observed)
In time of rising energy cost in Jamaica this is a double blow as with the ever increasing cost of fuel, the change in our bills are more pronounced as a 5% increase in consumption could result in an increase of greater than 5% based on the every increasing fuel charge component of our bills.
Voltage instability & Transients.
Electronics are very susceptible to surges, spikes, transients and harmonics. The ANSI C21.1 metering standards specifies the magnitude and amount of surges these meters are expected to withstand, so as to address this problem, which was never an issue with analog meters, which had an air gap, which was used to dissipate these energies.
The big question is apart from the design mandate by ANIS C12.1 and ANSI C 12.20 does the JPS uses any additional circuit protection to avoid damage to these meters, which could affect their readings.
So having said all the above, what can we do about it?
Not much really, the best way as I have said on a number of occasions is energy conservation as well as being aware of your meter readings i.e. read the and record your own meter reading as close as possible to when the JPS meter reader usually comes.
I am asking readers to assist me with some information.
For those who currently have a digital meter can you provide the following on this blog:
- Make/Manufacturer of the meter.
- Date of manufacturer
- Any additional information that is recorded on the meter.
Note : I do NOT need your meter number
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