Power meters measure up

Yokogawa’s WT3000-2A and WT210 digital power meters are now certified to carry out the stand-by power tests specified in the new IEC 62301 standard. This defines the stand-by mode as the lowest consumption of an appliance connected to the mains but not performing its main function.

The company's meters were tested by Kema Quality and both the WT3000-2A and the WT210 complied with all requirements for IEC 62301.

The standard has been introduced in response to the growing awareness of limited energy resources and the need for power savings in household electrical appliances.

Stand-by power refers to the electrical power consumed by appliances or equipment when they are switched off or in a stand-by mode. Typical examples might be a DVD recorder set to record in timer mode or a dishwasher timed to make use of off-peak electricity tariffs.

Measuring stand-by power is generally regarded as challenging because general-purpose power meters do not usually have the accuracy to measure low power values (typically less than 1 W) accurately.

In addition, average measurements over a period of time may be required to compensate for the effects of surges on the AC powerlines.

The standard describes the test methods and requirements for both the mains supply and the test equipment. The major requirements are for a digital power meter with fundamental active power accuracy of 0.5% or better, measurements down to 0.01 W or lower and the capability of including components up to the 49th harmonic (2.5 kHz).