Smart Meter Reliability
Figure 1. Typical smart meter. |
The power company meter reader is going the way of the bridge toll taker and the gas station attendant – made obsolete by small and inexpensive electronic circuits. But what about their reliability? More than 10 years ago we conducted a reliability analysis of an early prototype smart meter design and predicted failure rates of 12% to 24% for the first year of service, with the rate dropping significantly thereafter. In a metropolitan area having 3 million households for example this would have amounted to a predicted 360,000 to 720,000 failures in the first year of service if every household was supplied a smart meter. Certainly the predicted reliability has increased substantially since this early design. Now that the product is rolling out, the actual failure rate is less than 1% for the first year of service based on our review of public utilities regulators’ reports.
The analysis technique we used to predict the failure rate is called Mean Time Between Failure, or MTBF, and is commonly required by the military as a tool to help ensure that new weapons systems have a very high degree of reliability. The military standard is titled “Department of Defense, Military Handbook Reliability Prediction of Electronic Equipment.” The technique is also described in the “Bell Communications Research (Bellcore), Reliability Prediction Procedure (RPP) for Electronic Equipment.” The Bellcore reference was used for the reliability analysis of the early design smart meter; it is much less conservative than the military standard because of the relatively extreme conditions that military equipment is expected to survive.