A new study by scientists at the Dutch University of Twente has revealed that smart meters may be giving erroneous readings of electricity consumption. According to tests conducted as part of the study, readings can be up to as much as six times higher than actual consumption. Though the meters have passed standards tests, these faults remain undetected because of their inability to measure some of the latest devices in use.
This unreliability is particularly observed when monitoring the outputs of LED lights fitted with dimmers. 60 per cent of the meters tested showed results as much as 582 per cent (almost six times) the actual energy use, while some of the meters under-recorded consumption by up to 30 per cent.
While many types of LEDs are not designed to be used with dimmers, even those that were especially manufactured generated false readings in some meters. To ascertain the cause of the malfunctioning energy meters, the researchers took them apart and discovered that faulty units that gave excessively high readings contained a Rogowski coil current sensor. They also discovered that meters giving a lower than actual deviation were fitted with a Hall effect-based current sensor. The inaccurate readings were caused by the meters’ inability to process the erratic waveform of the electricity being consumed.
Frank Leferink, professor of electromagnetic compatibility at the University of Twente, explained that the energy meters tested by their team met all the legal requirements and were certified. However, these requirements didn’t make sufficient allowances for modern switching devices.
Holland has 750,000 of these meters fitted in businesses as well as homes. The network company responsible, Liander, said the problem was prevalent in meters installed between 2012 and 2014. Large companies were most likely to be affected by the fault. Households with solar panels and electric cars are also likely to be impacted.
To date, millions of smart meters have been installed around the world. Their owners will need to consult with the manufacturers to know if they contain the misleading current sensors. However, any replacement of meters would come at their own cost, making it an unacceptable case of testing standards failing the marketplace.
The study, titled Static Energy Meter Errors Caused by Conducted Electromagnetic Interference, was published in the scientific journal IEEE Electromagnetic Compatibility Magazine.
INDUSTRIAL HOT WATER METERS
Electricity consumption readings can also be inaccurate due to the use of cheap energy meters, especially when measuring hot water.
Martin Wardell, managing director of data-logging software and meter company MWA Technology, says the use of low-quality meters with limited life expectancy is “an indictment of the lack of care taken by consulting engineers” who fail to recommend or install heat meters using ultrasonic flow sensors. The latter can operate accurately for up to 20 years.
Leading energy meter manufacturers such as Kamstrup, Diehl/Hydrometer and Itron insist on ultrasonic flow parts instead of mechanical flow parts/meters. Observing that selecting the right meter from the start saves money and prevents complications, Wardell blames estimators in building services and system integrators for the problem.
He explains that many consulting engineers have realised heat meters must be MIS Class II-certified. However, when it comes to water meters, they specify WRAS-approved and MID-certified models without mentioning the accuracy class. This should be R400 minimum, which are UK water utility grade meters.