Remote Disconnect Meters - Underrated and Underutilised
Although the technology for remote disconnect meters is available, reliable, and increasingly affordable, the North American acceptance of these meters is still very much in the embryonic stage.
Exactly what is a remote disconnect meter? Basically, it is a magnetic latching relay (typically 200 A for North American residential ANSI form factor applications, less for IEC meters), either enclosed within a separate meter socket adapter (collar) or integrated within a solid state meter’s housing, and some communication path (one-way or two-way) to the utility host or in-home payment station for control and monitoring. If it is part of an AMR system, host software for applications and network management will complete the “whole product.” Just as there are two schools of thought about retrofitting versus integrating communication with meters for AMR, the market demands both integrated and retrofitted disconnect devices. Remote can mean twelve inches for prepayment meters, or twelve time zones for an AMR-enabled disconnect meter.
Suppliers of magnetic latching relays include BLP and Gruner AG, a German company represented in the US by Goodman Components Corporation. Providers of meter socket adapters include Marwell Corporation and Ekstrom Industries. These and other suppliers of similar technologies work closely with meter manufacturers and AMR vendors to facilitate remote disconnect functionality.
Obstacles to be overcome to move remote disconnect metering from the fad stage to an industry trend include perceptual, regulatory, legal, technical and commercial.
There is also the misconception that a remote disconnect meter is synonymous with a prepayment meter. Prepayment metering, which requires remote disconnect functionality, is widely accepted internationally, but is still in the pilot and small deployment stage in the US. Unfortunately, it is often perceived as a form of socio-economic profiling, e.g. a way for the utility to exploit disadvantaged customers. For this reason many utilities are still gun shy to use remote disconnect meters, regard-less of their application. Regulatory agencies often share this view, and are reluctant to permit the use of disconnect meters.
Potential liabilities arise from the ability to control utility service from a distance. Electric range-tops and other appliances present a potential fire hazard if the residence is unoccupied when power is restored. One solution is to add a manual reset button for activation by the customer. The utility will ask the customer to turn off all electrical loads prior to enabling the reset function. Alternately, the reconnect may be activated from a remote location, so long as the customer is on the phone (the conversation is recorded) in the residence. Additional security can be assured by the incorporation of instantaneous current detection; if the surge exceeds a threshold value, the relay will immediately open.
For safety, remote disconnect meters (and prepayment metering) should only be deployed where the particular customer presents no potential health risks, for example associated with medical support devices or critical air filtration systems. As providers of last resort, utilities must ensure that remote disconnect meters will not deprive customers of vital heating or air conditioning during temperature extremes. Features are available to prevent service disconnect during these conditions, along with internal and remote overrides for AMR-enabled disconnect meters.
Technology and Innovation
Vendors have overcome technical challenges associated with disconnect meters, and are continually innovating to respond to market needs. Installation is now quick, easy, and non-intrusive (no hardwiring needed). A meter collar is installed between the meter socket and the existing meter, or a new integrated disconnect meter is swapped out for the old meter. Solid state integrated disconnect meters, such as those offered by Siemens and Metering Technology Corporation, may incorporate one-way or two-way communication (for AMR), time-of-use metering, and richer levels of functionality than provided by electro-mechanical meters.
Disconnect meters communicate with other devices for control and, often, automated meter reading. The growing AMR market has driven suppliers to offer a widening choice of communication options, including broadband, radio frequency, various powerline carrier protocols, pagers, PCS, satellite, and other media. The use of paging technology for control and monitoring is on the rise as coverage increases and costs decline. Many utilities have made major investments in RF infrastructure, and the market must respond with solutions that seamlessly fit their existing infrastructure.
Powell Power Electronics Company is introducing a load-limiting meter with multiple operational modes. A solid state meter with integrated relay and comm-unications, it can remotely control service, limit total current draw, and control specific in-home loads. Siemens has integrated disconnect, communications, and load limiting features with its Altimus solid-state meter. DCSI, which markets powerline carrier-based AMR systems, has integrated Altimus disconnect-enable meters with its commu-nications technology. Innovatec Corporation is a provider of two-way RF-based AMR systems for multi-utility applications. Innovatec’s Eric Dresselhuys reports that they now offer solid-state electric meters with remote disconnect functionality.
ANSI meter standards place limitations on internal heat rise for meters under continuous 200 A loads. Magnetic latching relays produce varying levels of heat. Until recently, this has resulted in the derating of most remote disconnect meters to 160 A continuous load. Michael Mayer reports that BLP has made a design breakthrough that will permit rating for continuous 200 A loads.
Justifying the business case is easy, compared to the other issues. AMR systems require lengthy, sophisticated business analyses due to the many variables factored into the equation. Remote disconnect presents a simple case for cost avoidance and process improvement:
- Individual truck rolls cost utilities at least US$50 (probably more if fully burdened), or US$100 for a complete disconnect/reconnect cycle.
- Hard-to-read, dangerous-to-read, and physically distant meters cost much more to service.
- Remote disconnect functionality is available in the US$200 to 325 range; prices will drop as more are deployed.
- A small percentage of chronic, repeat customers (approximately 0.5 to 5%, depending on location) cause the majority of disconnect/reconnect service calls, with about three disruptions per year being typical.
- Transient housing (student apartment complexes, RV parks, marinas, manufactured housing, etc.) account for much of the remaining service calls, which are frequent and fairly predictable.
- Disconnect/reconnect cycles will continue to recur, regardless of whether they are manually or remotely executed.
The bottom line is that remote disconnect meters can have hard money payback in one to two years.
Beyond reducing costs for the utility, remote disconnect meters allow for improved customer service. Peregrine’s Myron Anduri gave an example for a rural co-operative. Once a customer has made payment for service restoration, the utility must respond within a required time limit. For a rural co-op, a single service call to a distant customer location may take fours hours’ round trip. On a weekend or during inclement weather, avoidance of a single service call of this type can more than justify the investment in a disconnect meter.
The remote disconnect meter is the missing link in distribution infrastructure. Here in Northern California, blackouts are an all-too-frequent reality. New technology trials are demonstrating load management and direct load control within residences, i.e., set-back thermostats, pool pump relays, electric water heater cutoffs, and others. Combined with eventual time-of-use metering, these technologies will provide peak shaving to utilities and monetary relief to customer volunteers. The gap between these extremes – whole house load control – can be filled through the use of remote disconnect meters, which would offer a new level of system management and customer choice. Instead of mandatory regional outages, utilities could offer new tariffs – at substantial savings – to those customers willing to participate.
The author encourages utilities to take a remote disconnect meter for a test drive.