Wrong Plug, Wrong Outlet? Dutch Meter Study finds False Readings
by Mason PUD 3 on
March 06, 2017
PUD 3 tests every meter on certified equipment so customers can have confidence their usage is measured fairly and accurately.
READING TIME: 5-7 Minutes
For those who have traveled to Europe, a harsh surprise awaits if they expect their hair dryers and other electronics to handle a foreign country’s different plug designs and higher voltages.
Similarly, counting on another country’s advanced meter standards and criteria, inconsistent with U.S. specifications, should come with a large warning label.
The Science Bulletin website posted an article (Saturday, March 4) citing a study conducted in the Netherlands that claimed inaccurate readings on a select number of solid-state electricity meters. Interesting to note that none of the meters appeared to have been designed for use in the United States. The headline and some of the study’s claims are alarming to read. However, just like trying to use a U.S. power cord in a European outlet, they are ultimately not applicable to Mason PUD 3 customers.
Remember this impressive sounding name, we’ll come back to it: “Rogowski Coil Current Sensor.”
Several quotes from the abstract published in the IEEE Electromagnetic Compatibility Magazine, on which the article is based:
- Consumers are sometimes complaining about higher energy readings and billing after the change to a static meter, but there is not a clear common or root cause at present.
- Several field investigations failed to identify a clear root cause of inaccurate readings of static energy meters.
A laboratory test claimed errors of up to +582%. The abstract states, “After dismantling, it was revealed that the meters with the positive deviation used a Rogowski Coil Current Sensor.”
Mason PUD 3 does not use meters with a Rogowski Coil Current Sensor.
Rogowski Coil Current Sensor
Electrical service reliability, and the trust that it breeds, if of utmost importance to PUD 3. Accurate metering is a part of that reliability and trust relationship with our customers. Therefore, it is imperative that the meters PUD 3 deploys are accurate and trustworthy.
In 2006, PUD 3 purchased some Sensus-brand solid-state meters, a popular product for the industry. The meter’s claim to fame was the Rogowski Coil, which was supposed to make the meter more accurate. As with all meters we receive from manufacturers, the PUD 3 meter shop ran stringent tests, which showed that the meters were unreliable, and produced unrepeatable test results. Based on these tests, PUD 3 staff replaced all deployed Sensus meters. We haven’t ordered from them again.
Remember the “Rogowski Coil Current Sensor”? It’s at the core of all the meter errors identified in the Netherlands study.
Advanced Meter Testing
From the very start of PUD 3’s grid modernization project, all advanced meters have undergone a rigid evaluation process to ensure manufacturer tests match PUD 3’s evaluation for accuracy.
We test our meters on two state-of-the-art testboards. As recommended by the National Institute of Standards & Technology, we have a third-party tester re-certify the PUD’s testboards every two years. We have a history of repeatable results dating back to 2006. They show that the standards inside the testboards remain accurate to 0.01%.
Residential customers often ask about the metering of switchable power supplies or certain lighting systems. The linked article specifies energy-saving LED bulbs controlled with a dimmer as a contributing factor to the metering errors.
Here’s where we get a little technical; bear with me. The kind of power used in specialty electronic devices such as dimmers, motors, and other nonlinear loads is measured in var-hours. The amount of vars used measures the effect of a concept called the power factor. Because of the relatively small loads and predominantly inductive characteristics of common electronic devices found in residential or small commercial services, PUD 3 meters placed on homes are not equipped with var registers, and we do not bill those accounts for the specific use of vars. Even if your home has a lot of LED lights, dimmers, small motors, and a ductless heat pump (w/ a VFD), your usage of vars is not being metered or billed, so the related concerns brought up by the lab study are not applicable.
That said, the var-hour registers found on the meters used on large commercial & industrial accounts which are billed for vars (those with lots of big motors ramping up or down or other energy-intensive uses), go through the same testing process as the watt-hour register. Those results are sent by the manufacturer with each shipment.
PUD 3 Meter Testing Policy
PUD 3 periodically tests and inspects its meters to ensure a high standard of accuracy. When a customer has a higher than expected energy bill, a common reaction is to question the accuracy of the meter. Before a meter test, PUD 3 staff take steps to identify the cause of higher consumption. If the reading came from a meter reader, a check read is performed to rule out accidental misreads. Usage history at the home is reviewed by our trained energy efficiency advisors. Often a free home energy survey is performed. In many cases, this helps to explain the energy usage.
If a customer is still curious about the accuracy of their meter, the PUD’s trained IBEW Journeyman Meterman makes a site visit to test the meter in the presence of the customer (during business hours). This way, all parties involved can be confident that the meter is within an acceptable 2% threshold. If the meter operation is over 2% in favor of the PUD, the electric bill will be adjusted over a period not to exceed six months and no charge will be made for the testing.
A customer may request additional meter tests. If the meter registers correctly, the customer pays $50 for the test.
The bottom line is that the accurate measurement of energy use, based on accepted U.S. energy industry standards, is an important goal of any electrical utility. That’s why PUD 3 tests every meter on certified equipment so customers can have confidence their usage is measured fairly and accurately.