The first incidences of interference in electricity meters were reported at the end of 2010. In some circumstances, meters were found to be sensitive to electromagnetic interference between the frequencies of 2 to 150 kHz generated by everyday equipment such as certain supply units and voltage converters. Utility companies decided almost immediately not to accept meters that had not been tested in this frequency range. This created a big problem for the manufacturers. NMi responded by developing a solution to enable testing of electricity meters in this frequency range.
“Thanks to the test method, I was able to market my measuring instrument immediately with proof of immunity!”
Clever test method
The existing regulations did not require testing for immunity from interference in this frequency range. However, the interference caused faulty measurements, resulting in consumers receiving invoices based on the wrong values. At the beginning of 2011, NMi therefore developed a clever test method which could demonstrate immunity from this electromagnetic interference. Manufacturers of Watt-hour meters could then quickly prove compliance of their measuring instruments and convince their customers that the measurements were accurate.
In mid 2012, CENELEC published a document describing the official test method, which is partly based on NMi’s knowledge and experience. It also set down clear assessment criteria, creating the desired clarity for manufacturers.