Increase AMR Benefits with Outage and Power-Quality Reporting

Increase AMR Benefits with Outage and Power-Quality Reporting

By Steve Hodges, Design Concepts International

Most of us are familiar with the costs and problems associated with manual meter reading. We`ve also heard the promises and proposed benefits of AMR. Utilities report average manual reading costs varying from $6 to $20 per year, per meter. These estimates are primarily based on the direct cost of paying meter readers to walk or drive around. Significant additional expenses such as worker`s compensation claims and legal expenses have also been well documented. Although most utilities have a variety of hard-to-read meters, they also have many that can be considered easy to read and therefore cheap to read AMR alone may not prove economically feasible. However, the analysis changes radically if the same AMR equipment provides other significant benefits with little or no increase in cost. The value of the complete system dramatically increases, and the economic justification becomes clear.

One of the most attractive and practical add-on functions of an AMR instrument is the real-time reporting of outages and power-quality problems. During the past 20 years, the impact of momentary outages, and under- and over-voltage conditions of any length, have become significant. At one time, primary utility loads were motors, lights, heaters and the like. If power was interrupted for a fraction of a second, these units weren`t significantly disturbed. But times have changed. The utilities` customers have also changed, and they are much more critical. VCRs and digital clocks begin flashing 12:00 and require reprogramming. Variable speed drives and electronic controllers trip off line and can shut down delicate plant processes. Irrigation pumps quit pumping. The inevitable result of all of these is the same: unhappy customers. Many of these customers call the utility to ask what`s being done about their power quality. Today, there`s a good chance the response will be inadequate–since the utility may know less about the problem than the customer.

Many electric utilities today still rely on customer calls to identify complete power outages, as well as other distribution system problems. After all, it is the affected customers who realize the immediate impact of an outage or power-quality problem. Alternatives to the “customer will call” approach have traditionally been prohibitively expensive. This is no longer the case. Five years ago, DCI teamed up with Idaho Power to create the Sentry system. This system provides detailed, real-time reports of all power outages longer than one cycle. Later models also began reporting under- and over-voltage conditions (at well under $100 per location). This information provides a utility with a complete picture of its power quality from the customer`s point of view.

The system is comprised of a master receiving station and an unlimited number of low-cost, remotely located reporting instruments. When an electric power outage is detected, the master station is called to report the details of the event. The master processes calls from the Sentry modules providing the utility operations center with a real-time picture of distribution system conditions. A single phone call can report up to eight voltage transitions. The Sentry also supplies relative timing data to the master so that an accurate real-time and date for the event can be attached to the report.

The master station is a Windows-based computer located at the utility operation center. Each Sentry is strategically placed in a home or business at a location on the distribution system which will provide valuable information regarding system performance. Good locations include those near reclosers, fuses, and other automatic switching equipment and areas with uncertain voltage quality.

A Typical Outage Report

The collected data can be viewed on the master station screen, printed or transferred to another computer. On-screen and printed data also include all location information concerning the Sentry such as substation and feeder names, and any reclosers, switches or fuses upstream from it. By comparing the outage with information reported by other nearby Sentry modules, the system quickly identifies the real-time condition of the distribution system and suggests the open device. This concept is the foundation for most trouble-call analysis programs.

The data can also be used by engineering personnel to evaluate protective device coordination and determine areas which need the most urgent attention. Duke Power correlates apparent recloser operations with lightning strikes by comparing the timing of reported outages to that of lightning strikes. According to Duke engineer George Bowden, the results help Duke budget maintenance dollars appropriately among competing activities such as tree trimming and lightning protection.

Under- and Over-Voltages

In general, a computer can handle most dips or under-voltages lasting less than a cycle. Likewise, they can handle very short positive spikes or impulses. However, as the dip or surge increases in duration, the computer`s susceptibility also increases. While most computers can handle an 80 percent voltage condition for one cycle, very few will endure it for several seconds. In a major study of power quality, the National Power Laboratory monitored 235 randomly chosen locations in the United States and Canada. After 1,800 site months of experience, they reported that the average 120-V wall receptacle experiences 443 potentially destructive or disruptive disturbances per year.

Under-voltages, which accounted for 60 percent of the disturbances, can cause computer resets, memory loss, data loss and electronic component overheating. Over-voltages, which at 29 percent form the second largest group, can cause component overheating or destruction. They may also trigger protective devices, causing equipment resets and data losses. It`s obvious that there`s much more to the power-quality story than just outages, which made up only 3 percent of the total number of disturbances. In addition to reporting momentary outages, the Sentry model can be programmed to report voltages which exceed a specified level for a specified number of cycles and voltages which drop below either of two specified levels for a certain number of cycles. When the designated condition occurs, the Sentry reports the date, time and duration of the event, plus the minimum or maximum voltage measured.

Customer Notifications

To further demonstrate the value of outage and power-quality reporting to the utility, consider how this information is being used today. For each incoming call, the master station reads the call type and the time of the call, then compares them to the user`s instructions. Based on these settings, the system may dial a phone number and speak a digitized voice message, send a fax report to a specified phone number, transmit data to a pager or send the event information directly to a third-party SCADA or GIS.

All of these outage notification techniques are designed to share the information with all interested parties. The data may become hundreds of green or red lights on a map, or they may turn into individual voice messages to a customer or service representative. Either way, everyone involved has a greatly improved picture of system conditions. In summary, these functions provide a great deal of raw data concerning outages and other power line disturbances. The software which pulls all the data together to analyze the various outage calls is called Trouble Call Analysis. Its goal is to analyze the real-time reports to quickly suggest where the outages are and what device in the distribution system may be open.

The Ideal AMR Design

The real gain comes by combining these features with AMR at no increase in price to provide a significantly increased benefit for the utility`s dollar. The top priority of a basic residential AMR device is low cost, with prices starting in the low $50s. It should mount inside the meter, use the existing telephone line to report power consumption (either as scheduled or upon request) and provide a detailed report of all power outages. It should feature:

transparent operation to make it nearly invisible to the customer, scheduling AMR calls during early morning hours, checking for “telephone in use” before going off-hook and immediately hanging up if the customer picks up the phone during a report;

reports on demand so that when the homeowner calls the utility to request a reading, a command can be sent from the utility to the AMR device; or when the customer hangs up, the device will call in an AMR report;

both local and remote programmability of all operating parameters;

reports of peak demand and time/date of occurrence; and

tamper detection.

Most importantly, it should be reliable in all light conditions, exhibit wide temperature and humidity range operation, and be impervious to voltage spikes and variations. Enhanced AMR functions provide even more benefits to both the utility and the customer. The most obvious is time-of-use (TOU) metering and billing. With little additional cost, the standard AMR device can report a variety of programmable periods and rates. Once you have the right hardware, adding TOU features is a simple matter of programming and memory. The end result is a very low-cost AMR device teaming up with the old reliable mechanical meter to create a sophisticated reporting instrument.

Other features should be available when the application and the cost are justified:

remote monitoring of temperatures, equipment status and alarms;

remote control of energy consuming equipment;

information gateway communicating to and from the home;

Remote interface controlling in-home devices; and

gas and water meter interfaces.

When considering the justification of AMR equipment, remember: The same equipment that provides basic AMR should provide other significant benefits with little or no increase in cost. As a result, the value of the complete system dramatically increases and the justification becomes easy.

Author Bio

Steve Hodges founded Design Concepts International in 1989.

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