Protocol standards facilitate AMR implementation

Ted York
THY Consulting Inc.

Recent American National Standards Institute (ANSI) protocol standards will reduce the cost to support metering operations and accelerate the rate of innovation and change within the metering industry. Electric utilities who purchase and apply meters must consider these new standards in order to optimize their operations, and the greatest advantages will come to those who have the best access to quality information.

With electromechanical meters, collecting data was easy. It consisted of someone visually reading a couple of 3- to 5-digit values from standardized dials, manually recording the value on a billing form, and returning it to the utility for transcription and bill generation. Anyone could be trained to be a meter reader in minutes.

The advent of more complex rates and electronic registers resulted in changes to the method of data collection. The dials were replaced by displays—which scrolled through selected data values while most of the information remained inside the meter for retrieval via a communication tool.

Each style of electronic meter communicated using its own protocol to provide internally stored values in formats unique to each manufacturer. Usually a new meter design resulted in some different control parameters or values being added, some values recorded in new formats, and all being transported with a slightly modified proprietary protocol.

Today some meters store hundreds of thousands of pieces of metering data. Many moderately priced meters go beyond conventional metering to analyze the service where they are installed, adapt to that service and even notify the installer if the service is improperly wired.

While handheld readers are still used, an increasing number of meters communicate directly with automatic meter reading (AMR) systems. The users of these legacy meters are burdened with multiple computer systems from different suppliers using dozens of proprietary protocols to communicate with the user’s meter inventory. Utilities are required to buy separate software from each meter manufacturer in order to program options in these meters. Third party handheld readers and metering systems have to be updated for every new meter type added to the mix, and only those who can obtain a license from meter manufacturers can even develop software to read the meter.

Standardizing meter communications

Several years ago ANSI, Automatic Meter Reading Association (AMRA) and Measurement Canada (the Canadian standards body) got together in a series of meetings called Tablefests. Their objective was to develop a solution to these increasing obstacles for meter communications. After five years of intense work involving over 30 utilities, all of the North American meter manufacturers, several third party software providers, a number of consultants, and several other interested parties, three significant ANSI protocol standards have emerged and a fourth is on the way.

The standards are aimed at a variety of metering products including meters, recorders and add-on modules. As a result, the standards all refer to this class of metering related products as end devices instead of meters.

The standards include:

  • ANSI C12.18-1996 Protocol Specification for ANSI Type 2 Optical Port: This standard is a very simple transport protocol, designed to transport data structures as defined in C12.19 via the infra-red optical port currently in use by most North American electricity revenue meters.
  • ANSI C12.19-1997 Utility Industry End Device Tables: This standard defines a set of flexible data structures for use in metering products. In order to support innovation, the standard also allows for inclusion of manufacturer defined tables.
  • ANSI C12.21-1998 Protocol Specification for Telephone Modem Communication: This standard extends C12.18 and C12.19 to accommodate modem communications at the meter.
  • ANSI C12.22 – Protocol Specification for Interfacing to Data Communications Networks: This working draft for a standard extends C12.18 and C12.19 to support data network communications at the meter. This work is currently advancing under the joint work of National Electric Manufacturers Association, ANSI, AMRA, Institute of Electrical & Electronics Engineers and Measurement Canada.

These standards promise lower meter operation costs and simplify meter interface processes. Common protocols and similar structures give meter purchasers greater ability to exploit the functionality of the meters they buy. Historically, the lack of open standards meant that many electronic meter capabilities remained hidden and were seldom, if ever, used. The standards enable a new openness in metering that did not exist before.

The standards also provide a common vocabulary to describe meter capabilities: Users learning about manufacturer A’s standard protocol meter have a much higher potential for using that knowledge on manufacturer B’s meter. Legacy meters are described in unique terms defined by each meter manufacturer. Now a “negotiate service” (part of the communications startup process) will mean the same thing to all meters no matter who manufactured them. Data structures are defined as “tables” and all commands and functions are referred to as “procedures.” Self-describing data structures let users read the meter to find out what parameters measure kWh and which are kVARh. Common data structures for familiar functions follow the same rules. This keeps meter personnel from having to mentally adjust every time they switch between products manufactured by different companies.

The standards also allow a single software set to perform common programming and data retrieval processes on meters designed independently of the software developer. That is, utilities or third parties can more easily write useful software to exercise ANSI protocol meters with little or no assistance from the manufacturers of those meters. In fact, most meter firmware (for products using these ANSI protocols) developed to date has used a common, commercially available test software package for conformance tests. This commercial software, Table TstBench from NERTEC, handles both standard and manufacturer-defined tables and procedures.

Use of this capability means that the time between acquisition of a new meter and being able to effectively use it can now be collapsed to seconds rather than weeks or months. This also enables the purchaser to more completely evaluate sample meters at a rapid pace.

The use of common software by very dissimilar ANSI protocol meters encourages innovation. It allows manufacturers to introduce new features and products without the costs or delays currently caused by having to keep software up-to-date in parallel. Since software can now be written to effectively communicate with these meters without licensing, it is expected that meter manufacturers will also enter the third party software market in a major way.

Pressures spur adoption

Market pressures for ANSI protocol meters (APMs) have reached critical mass. The entire Canadian market is closing to new meters that do not meet the ANSI C12 protocols for both transport and data structures. Initial opposition by a few suppliers is dissipating as they sense a change in the marketplace and prepare their own ANSI protocol products. While some manufacturers of meters and software tools may attempt to delay broader acceptance, leading manufacturers will be ready to meet the increasing market demands.

The California Public Utilities Commission (PUC) has required the use of ANSI transport protocol C12.18. Other states in the deregulation process are expected to follow. The PUC did not require C12.19, the AMRA tables standard. The C12.18 protocol, however, was written specifically to support the AMRA tables, so moving products to C12.18 without C12.19 becomes a waste of development resources.

Several utilities, led by the Southern Company utilities, have made the AMRA tables a meter procurement requirement. An even larger number of utilities and energy service providers have declared preferences for APMs, but have not taken as strong a stance as Southern Company.

Imminent announcements of innovative new products should break the dam and further accelerate the move to APMs. In anticipation of these pending product offerings, some analysts expect a switch to APMs from current proprietary protocols at a rate faster than the earlier switch from electromechanical to electronic polyphase meters. To take advantage of this next paradigm shift in metering, suppliers and potential users of this technology must position themselves to take advantage of a surge in the use of these meters beginning in the third and fourth quarters of 2000.

Ted H. York may be contacted at THY Consulting Inc. is an independent consulting firm.

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