An electronic energy meter (EEM) is used in residential, commercial and industrial applications to measure the amount of energy supplied or produced. One of the major advantages of EEMs is that in non-linear loads, its metering is highly accurate and electronic measurement is more robust than that of the conventional mechanical meters. Companies that use EEMs can benefit in three significant ways. EEMs reduce theft and corruption on electricity distribution networks because of their design and prepayment interfaces; they measure current in both phase and neutral lines and calculate power consumption based on the larger of the two currents; and they improve the cost efficiency and quality of electricity distribution.
By Srabani Sen
Wednesday, May 09, 2012: EEMs vary in their features and are priced accordingly. The purpose of this article is to help the reader select the right EEM from the vast number of choices.
What’s new in the market?
There are different measuring nodes in power systems. These encompass generation, substation feeders, distribution transformers, industrial and commercial segments, and small commercial and residential segment. Each measuring node has its own requirements for measurement functionality and other associated features. Hence, a wide range of EEMs are available in the market.
The most prominent in the market today are the electromagnetic, static and induction type of electromechanical meters. Among these, there are single phase energy meters with mechanical displays, single phase energy meters with LCD displays and anti-theft features, three phase energy meters with LCD meters, high accuracy TRI vector meters with multifunction displays, etc.
Secure Meters Ltd has complete metering solutions for energy utilities, and commercial and industrial
customers. Its customers include OEMs, contractors, panel builders, switchgear panel builders, industrial and commercial establishments. “Our solutions include products, solutions and value added services to utility customers. It also includes smart meters and advanced metering infrastructure solutions (AMI solution) with remote connect-disconnect functionality, multiple communications support with a data collection system, and integration with utility backend systems,” says Kamal Pagaria, manager, marketing–C&I, Secure Meters Ltd.
Some of Eaton’s flagship EEMs include Power Xpert Meter 2000 series, Power Xpert Meter 4000/6000/8000 series, IQ Meter series, IQ Analyser series, Power Xpert Energy Viewer and Power Xpert Meter Profiler, enclosed meters, etc. “Eaton’s advanced meters provide accurate real time system values. They capture waveforms and system events, and display data directly on the device through onboard Web servers or through a software monitoring solution. These features protect equipment and processes from harmonics, voltage fluctuations and transient over voltage conditions,” states Deepak Sharma, vice president, marketing, power quality, APAC, Eaton Corporation.
Energy meters have been useful not only to measure the power units but also to record power consumption, and to monitor and evaluate energy bills. “Customers are keen on a reliable energy meter as the bills usually keep fluctuating. Manufacturers, therefore, go through stringent quality controls and research to develop energy meters that comply with stringent standards like IS: 13779: 2000, which each manufacturer should adhere to. Our high quality power meters are tested under IS: 13779: 2000, IRDA, RF and IR,” informs Deepak Sharma. Energy meters have to meet the requirements of some more
standards like input output interchange, phase neutral interchange, low power consumption, input output interchange with current flow back into meter, correct energy records with great accuracy under current connection, instant startups, anti-tamper features, tamper indications, etc.
Towa Engineering Works offers various types of meters and controllers for power and energy measurement, data analysis and to control electrical equipment. Some of its popular meters are single phase power and energy meters, dual source energy meters, three phase multifunction Tri Vector energy meters, maximum demand controllers, etc. “We offer customised designs to our customers. Our products are reliable and well protected,” says RS Miglani, managing director, Towa Engineering Works.
Kusam Electrical Industries has energy meters suitable for use on control panels. “We do not supply energy meters for monitoring revenues. For the control panel application, the types of energy meters we offer are with LED or LCD displays. They are available in 96 x 96 mm, 144 x 144 mm and 96 x 48 mm sizes. The first two types can display many functions such as AC volts, AC current, active power, reactive power, power factor, frequency, harmonics, demand, etc,” informs Chandmal Goliya, managing director, Kusam Electrical Industries Ltd. Kusam’s model—DMDPW ( 96 x 48 mm) has an LED display and can measure and display DC volts, DC current, DC KW and DC KWH. It also offers two types of energy meters with LCD and LED displays.
“Genus Power Infrastructures provides closed loop metering solutions that offer operational advantages to energy utilities, enabling transmission and distribution (T&D) loss reduction and thereby enhancing revenues,” informs Rajesh Sharma, senior manager, marketing, Genus Power Infrastructures Ltd.
Genus industrial meters of Accuracy Class 1S and 0.5S are specifically designed for commercial establishments, industrial houses, substations and agricultural setups. These are multi-tariff meters measuring active, reactive energies and demands. They have unique anti-tampering features with tamper events and load profile recordings. Its Class 0.2S ABT (availability based tariff) compliant meters ensure reliable and precise metering on high voltage networks.
According to Deepak Sharma, the major technological innovation that has taken place in this domain is the development of EEMs. “These meters are still in the development stage and have been commercialised in the area of industrial/bulk metering only,” he adds.
Some of the major technological advancements that have taken place in EEMs are microprocessor based metering systems, password protected energy meters, programmable CT/ PT ranges, inbuilt memory, consumption of low internal power, LCD displays, tamper proof features, etc.
Currently, static energy meters equipped with state of the art measurement, data logging capability, advanced revenue protection feature sets, load control functionality in case of prepaid and smart metering functionality, are in demand. “Smart energy meters are now more technologically advanced with different inbuilt or modular communication systems that incorporate cellular technologies like GSM, GPRS, 3G and 4G, or licence free radio options for data collection
from central locations, which eliminate any manual intervention,” states Kamal Pagaria.
Static meters are also smarter with the capability to log system abnormalities and tampering for further analysis and revenue protection. Prevention, detection
of fraud, and the prevention of new cases of tampering are the areas where energy meters are continuously improving. For example, energy meters suitable for the R-APDRP programme of energy auditing and loss accounting have features for data logging, and have the remote meter reading facility, common meter reading protocol as per the Indian companion DLMS standard, and integration with the utility system.
Says RS Miglani, “The present range of meters use high speed microprocessors with 6 channel Sigma Delta digital converters. Due to the fast processing of data, we can get reliable information. Further, the Flash memories can store load surveys for two months.”
Another advancement that has taken place is in billing systems. Says Rajesh Sharma, “The advanced meter system with the tariff indicator can take care of
electricity billing using what is called the ‘prepaid energy meter’. It can improve cash flow management in energy utilities and can reduce the problems associated with billing consumers living in isolated areas, thereby reducing the need to deploy manpower to take meter readings.”
In a nutshell, extensive research and development in the energy metering area is going on to modify domestic meter designs and for raw material substitution
to minimise costs. Work is also on in the industrial meters/bulk meters domain to improve quality and accuracy and to develop pilfer-proof meters. Other focus areas are in the development of static energy meters for domestic, commercial and industrial purposes.
Energy efficient features
Energy meters have various features that help to achieve energy efficiency directly or indirectly. They offer comprehensive and state of the art power and energy measurement and monitoring that reduce day-to-day operating costs. Some of their energy efficient features are:
- The meters maximise equipment utilisation by monitoring circuit loading, which helps in avoiding overloads.
- They manage energy utilisation to help reduce peak demand charges and power factor penalties as well as to identify excessive energy consumption.
- Most of the meters provide graphical comparison views that dramatically improve the ability to benchmark energy usage.
- Some offerings easily identify periods of high energy demand and develop a baseline to compare energy usage and identify anomalies.
- Highly accurate energy measurement (ANSI C12.20), onboard energy value storage, and time of use energy registers help to control energy usage.
- The meters record the total energy used and the maximum demand, thus aiding in energy management.
- Customers have to calculate the total load required by their organisation. Based on the total load, they can decide the CT/PT (current transformer/potential transformer) ratio. As per requirements, they need to procure and install the correct ratio of CT/PT.
Tips to choose right energy meters
As Kamal Pagaria explains, customers can choose an energy meter based on its application and intended metering segment requirement. For example, if the customer wants energy meters for tariff and revenue applications, then the approved utility energy meter with the applicable functionality should be chosen according to the metering segment. For sub-metering applications, there are multiple options available depending on the functions the customer is looking for—starting from credit meters and prepayment metering solutions, to multi-functional panel meters with energy management solutions.
Many features and parameters need to be considered when selecting an energy meter. The meters should range between 2.5 to 10 A, 5 to 20 A, 5 TO 30 A, 10 to 40 A and 10 to 60 A.
Customers should check some of the following critical parameters:
- Current carrying capacity
- Number of phases
- Critical electrical parameters
- Whether microprocessors have been used or not
- Class of accuracy. For general applications, an accuracy class of 0.5 is approximate. For precision measurement, the customer must buy 0.2 accuracy meters
- The connection should be done by a licensed electrical contractor who has experience in installing such instruments.
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