Ok, I am back. Keep in mind that anything I say about smart meters reflects state of the art at the time I retired, and technology is always advancing. I also cannot speak knowledgeably about the rate practices of public power authorities such as TVA, electrical co-ops, etc. At the time I retired, my budget for new meter purchases was a little over $2,000,000 annually.
The term "Smart Meter" can mean many different things to different utilities. There are smart meters that can be read by a handheld device through an optical coupler, which Gollnick correctly identified in his post. Some can be read through a short range radio signal from a van driving through the neighborhood. Some can be read through telephone, radio, and even satellite signal in really remote locations. Some can indeed shut off power, by either a breaker integral to the meter or control of an external disconnect. Most can be programmed to support various rates through the communications media mentioned above. Some systems can interact with the customer's PC, giving him information which can be used for load and cost management. The biggest advantage is that they have a memory register which can record data in short-term intervals, which gives us the capability to synthesize useage in our master PC's for new rates, rather than having to reprogram tens of thousands of meters for every rate innovation.
Every properly run utility has long had in place a meter inspection/testing program the goal of which is to comply with the regulatory standard for accuracy, which is typically + or - 2%.
Test sets are used with periodic calibration (every six months for us) traceable to an NIST standard. Testing is usually done through a statistical sampling of multiple meter populations
based on manufacturer, meter type, and meter age, although certain commercial and industrial meter installations are 100% tested.
There are three primary reasons to install smart meters.
- cost savings on meter reading
- making innovative rates possible
- defering capital costs to add generation
The first is obvious, entails only a fairly simple engineering economics analysis, and needs no further explanation.
The second and third are usually tied together. Increasingly, regulatory bodies are encouraging utilities to find alternatives to adding generation capability. Every utility has one peak usage hour during a calandar year. The utility must have the generating and transmission/distribution system capacity to serve that one hour without burning some system component up. The most cost ineffective capacity is that which is called upon only once a year, but it must exist, whether the utility builds it or buys it from someone else.
Most non-traditional methods to reduce peak usage require a smart meter. Rate innovation which rewards moving usage to off-peak periods through variable rates (time-of-use programs) is one method. Another is giving a rate break to customers who agree to being subject to on-peak power interruptions a limited number of times a year. The most drastic is non-voluntary rotating power interruptions, which doesn't necessarily require a smart meter since elecrical systems can be switched in large blocks. Therefore, the smart meter can be used to enable the less intrusive means of reducing peak load.
Smart meters indeed do a better job of capturing some usage than mechanical meters did. Better metering of reactive and inductive useage is one type. Useage due to harmonics distortion is another. However, this certainly will not cause large increases on residential customers.
At the Southern Company, we tried to make rate innovations a matter of customer choice, not coercision. I hope that my successors can keep it that way.
