Reliability assessment for static electricity meters

The reliability of static electricity meters is of vital importance to both the users of energy and providers of energy. It is also of extreme importance to designers and manufacturers. An electricity meter, unlike other electronic equipment, is permanently on circuit, is connected directly to mains without any protection, works in an unattended operation and is basically a maintenance free device. This unique combination of operating characteristics when combined with the fact that there are no standards, which cover reliability for such meters, presents the reliability engineer with a unique challenge. This paper discusses how studies on reliability of an electricity meter using conventional techniques of reliability prediction have limited meaning and are useful only in comparing the alternative designs. Reliability predictions using analytical methods do not really correlate with real field failure rates. In the new and more demanding environment in which complex multi-function electricity meters have to operate, studies on reliability testing or accelerated testing have been done to arrive at a realistic reliability estimate to complement the reliability prediction. Considerations related with accelerated testing of electricity meters are discussed. Further, field reliability of electricity meters is almost impossible to establish if the metering records of utilities are not accurate and proper. This problem is also examined in the paper