The impact of new technologies on the meter test industry
Metering International asked Lyndon Harfoot of MTE (Meter Test Equipment AG) in Zug, Switzerland; Charles S Weimer of WECO (Watthour Engineering Co Inc), Jackson, MS, USA; Joseph A Martin of Scientific Columbus Co in Dublin, OH, USA; and Graeme Mellis of Power Meter Technics CC, Gauteng, South Africa, to discuss these and other matters relating to metering accuracy. We are grateful to them for their input.
MI: In the light of new technologies such as AMR and prepayment, what are the implications for the meter test industry?
MTE: Meter test equipment is traditionally used to determine the accuracy of a meter. AMR technology is increasingly being applied to electronic meters, which makes testing the functions even more important. The functions of most electronic meters are checked by communicating with the read-out port. This requires a second scanning head and the appropriate circuitry. With prepayment metering, it is important that the internal circuit breaker be seen to trip once the energy is exhausted, and that this is recorded in the test report.
WECO: For years the meter test industry has focused on building equipment to test meters accurately. The additional features of electric meters such as AMR, prepayment technology and multi-function measurement capabilities mean that the electric meter test equipment should also be more capable. I think a utility or a user of electric meter test equipment would choose not only to perform accuracy tests, but also to perform all the possible tests and any related programming on the meter at one time and at one location. Another consideration with regard to the new solid state meters is calibration. Most of the present solid state meters are calibrated through software. There are special considerations on the test equipment used for calibration. I am not aware of any meter manufacturers providing utilities with the necessary software for calibration of their meters, and it would be difficult for the normal utility, using their standard test equipment, to do this. It means that the test equipment used by utilities is simply a means to verify the electronic meter’s accuracy.
SCIENTIFIC COLUMBUS: New meter features require additional personnel training, more complex verification and maintenance procedures and often higher operator competence levels.
POWER METER TECHNICS: The increased functionality of modern solid state meters places an additional burden on the meter testing process. It is no longer enough to test only the metrology and the register of a meter. All the functions, such as time-of-use configuration, pulse inputs and outputs, and primary equipment constants have to be verified. This means that it is becoming more and more difficult to test meters adequately using traditional manually operated test facilities.
MI: Are the meter test facilities at utilities sufficiently regulated, with adequate policies and procedures?
MTE: A wide spectrum of regulations and policies exists world-wide and though testing methods are well regulated, in reality these regulations are often not followed. How often are the IEC 736 (for testing equipment) values for distortion, stability, repeatability followed? Even IEC 521 has a list of reference conditions where the values for distortion are often ignored. National regulations can be separated into three trends: Well regulated areas, where systematic evaluation of meters in the network is carried out and accuracy errors are rarely found during on-site testing. Sparse regulation resulting in no systematic evaluation. Often meters are found to have errors during on-site testing, and subsequently large purchases of on-site testing equipment erroneously occur, which doesn’t solve the problem. Privatisation is introducing changes to traditional regulations, allowing non utility organisations to carry out testing services.
WECO: Most of the major investor-owned utilities in the US are regulated by the individual state Public Service Commissions. The testing schedules and specific tests are spelled out clearly in these cases. There is also a national committee (ANSI) in the US which provides `standards’ for tests and test procedures for manufacturers and utilities. Most utilities basically follow these guidelines. Another question might be: "Will the testing of new technology features within the electric meter be regulated or sufficiently regulated?"
SCIENTIFIC COLUMBUS: Meter test facilities in the US are usually professionally run and well regulated. This includes the establishment and maintenance of policies and procedures in compliance with applicable ANSI and NIST recommendations.
POWER METER TECHNICS: In most countries an independent government appointed body regulates the electricity supply authorities. This body is responsible for the approval of energy meters used by the supply authorities, and for the certification of these meters. Before any meter can be installed it has to be approved by the regulator, who will determine whether the meter complies with the relevant specifications by performing the necessary tests. If it does, the regulator will determine a suitable re-certification period for that meter and approve it for use. Before the utility can install a meter, it has to be certified by a properly accredited laboratory. The meter is then placed in use for the period allowed by the regulator for that type of meter. At the end of this period the meter either has to be removed for re-certification, or statistical tests are performed on a population of meters to see if the period can be extended. South Africa is one of the few countries in the world that has no statutory requirements for electricity meters. Each utility or supply authority determines its own requirements regarding the type and quality of meters to be installed, and meters are generally put into service for indefinite periods. In some cases local authorities even deliberately adjust meters to over-read and then publish a local by-law that allows them a much larger margin for error. The only recourse the South African consumer of electricity has is either a contractual agreement with the supply authority or a local by-law. Most supply authorities have meter testing facilities of some sort, but with the exception of a few Eskom laboratories, they are not accredited. In general these laboratories are poorly managed; no documented quality assurance system of written procedures is available, and reference standards are seldom traceable.
MI: Are utilities upgrading their calibration equipment as part of their customer service programme?
MTE: Our experience leads us to believe that the availability of testing equipment specifically designed to give better customer service has a direct effect. Utilities are now up grading their on-site testing equipment for challenged meters. Indirectly there is an increase in the functions required in electronic meters.
WECO: The largest push for upgrading calibration equipment has stemmed from the widespread purchase and use of solid state meters within the utility. Older test equipment possessed by a utility does not have the accuracy to test the newer high accuracy meters properly. In essence, with some of the older test equipment, the utility is testing the accuracy of their test equipment rather than the electronic meter they may be trying to test. We have not as yet seen the upgrading of utility test equipment that can be attributed to deregulation.
SCIENTIFIC COLUMBUS: Electric utilities are actively seeking ways of improving customer ser-vice and system reliability, at reduced consumer cost. To this end, the use of increasingly accurate computer and microprocessor controlled test equipment has greatly improved the quality of meter test operations, and significantly improved meter test efficiency.
POWER METER TECHNICS: A properly equipped and certified meter testing facility represents significant capital investment for an electricity supply authority. Most of the South African supply authorities are experiencing severe financial constraints and are reluctant to invest in a meter testing infrastructure suitable for testing modern multi-function high accuracy meters. Testing of meters is generally not viewed in the light of customer service, particularly since the supply authority is not bound by statute to provide this service.
MI: What are the latest developments in the meter test and calibration equipment market?
MTE: More sophisticated meters are available; therefore the testing equipment must provide the means of testing them. PCs make it easier to log the address and serial number of the meter. The use of the sample testing principle makes supervising the meters in the network efficient and cost effective. This will lead to an increase in sophistication of testing equipment in other areas, as has already occurred in Europe. The environment surrounding the meter (wiring etc.) becomes an increasingly important factor for on-site testing.
WECO: Test equipment has to be more flexible and perform more functions. Technology has allowed for more compact designs with increased capabilities. Today’s test equipment must do more, do it faster, do it better, do it with fewer personnel and be flexible enough to perform tests within the scope of the individual needs of each utility. Productivity is vital in today’s environment. Test equipment manufacturers must provide equipment that will allow utilities to compete in a deregulated environment.
SCIENTIFIC COLUMBUS: Portable meter test sets now rival the capabilities of many meter laboratories. Meter test and meter calibration can now be performed in many field environments, resulting in important logistics and labour cost reductions. The prevailing service voltage is detected and the appropriate range conditions are established without operator intervention. Clear operator and equipment safety improvements result. Individual test connections and test conditions are then automatically controlled as the selected test series is completed. The test conditions and test results can be saved and recalled from non-volatile memory. The resulting test record data-base can be exported via the test set’s serial communication port. On-site printed records are also available through this port, indexed by the meter identification number.