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Testing and calibration of electricity meters in India

The Indian government has launched a ‘Mission 2012 Power for all’ campaign, liberalised policies to improve the power sector, introduced reforms and energy conservation, and through its Accelerated Power Development and Reforms Programme (APDRP) has laid emphasis on distribution sector efficiency improvement. There are 28 states and 7 union territories in India, and the Indian constitution stipulates that both central and state governments are responsible for electricity and should play major roles.

With the enactment of the Indian Electricity Act 2003 on 2 June 2003, restructuring of the power sector leading to privatisation and unbundling of the erstwhile State Electricity Boards (SEBs) into corporates has begun. Nine SEBs have already been unbundled/ corporatised, and distribution in Orissa state and Delhi(unionterritory) has been privatised. A few old private distribution companies remain in some cities, like AEC in Ahemdabad, SEC in Surat, and CESC in Kolkatta.

Quality, reliability and customer service have become a major focus in the industry, and central and several state electricity regulators have been appointed and have started functioning. Some of the regulators have been established under the Electricity Regulatory Commission Act 1998, and will now be deemed to have been set up under the Electricity Act 2003. The Central Electricity Regulatory Commission (CERC) is mainly responsible for regulating tariffs for generation, inter-state transmission of energy including tariffs, advising the government on tariff policy, and promoting competition, efficiency and economy in the electricity industry.

The main functions of the State Electricity Regulatory Commission (SERC) are to determine the tariff for electricity (wholesale, bulk, grid or retail); to determine the tariff payable for use by the transmission facilities; to regulate the power purchase and procurement processes of transmission and distribution utilities; and to promote competition, efficiency and economy in the activities of the electricity industries. Twenty two states – Orissa, Haryana, Andhra Pradesh, Uttar Pradesh, Karnataka, West Bengal, Tamil Nadu, Punjab, Delhi, Gujarat, Madhya Pradesh, Maharashtra, Rajasthan, Himachal Pradesh, Assam, Chhatisgarh, Uttaranchal, Goa, Bihar, Jharkhand, Kerala and Tripura have either constituted or notified the constitution of an SERC.

Eighteen SERCs – Orissa, Andhra Pradesh, Uttar Pradesh, Maharashtra, Gujarat, Haryana, Karnataka, Rajasthan, Delhi, Madhya Pradesh, Himachal Pradesh, West Bengal, Punjab, Tamil Nadu, Assam, Uttaranchal, Jharkhand and Kerala – have issued tariff orders. Many have also issued a code for supply and distribution, as well as grid codes, metering code, code for open access and so on.

The Central Electricity Authority (CEA) has been designated as an agency for formulating national electricity policy; it advises government on technical matters and specifies grid standards and conditions for the installation and operation of meters. Under the Electricity Act 2003, 100% metering and installation of meters for energy accounting and audit has been made mandatory. (At present about 13 % of customers are not metered, in particular in the agricultural sector). The Act envisaged that 100% metering would be achieved within two years, but it is likely to take another two or three years to reach total coverage. Meanwhile rationalisation of tariffs to reduce and eliminate cross-subsidies have also been emphasised.


We all understand the importance of a good, accurate and reliable meter. In India most of the meters for grids, substations, and large industrial and commercial consumers have been replaced with static meters of higher accuracy (class 0.2 or 0.5) and multi-function meters. A large number of static meters (about 9 to 10 million) are being installed every year in the domestic sector. It may take another five years or more before all domestic meters are replaced with static meters.

Indian laws which came into effect in February 2003 require that every electricity meter needs to be approved and certified by the Bureau of Indian Standards (BIS) and marked with the BIS logo. BIS is responsible for specifying Indian national standards and granting type approval (product certification) based on the type test reports issued by accredited test laboratories. The Bureau also provides licences to manufacturers based on its approval of their manufacturing processes, which allow them to self-certify and mark the BIS logo on every meter they produce.

In the past the Indian Electricity Rules 1956, under section 57, specified the requirements for testing and acceptance limits for the meters installed at customer premises. The requirements regarding periodicity of testing, however, were left to state governments. As a result, in practice very few meters were periodically tested, except for those of very large power consumers or in the event of disputes or complaints.

Now the CEA has issued a draft for the “installation and operation of meters” which covers various types and applications such as grid meters, availability based tariff (ABT) meters between grid companies and state electricity boards/state transmission companies, substation and feeder energy accounting meters, industrial, commercial and domestic meters. This document also specifies the broad technical specifications and requirements for periodic testing of various types of meter and associated instrument transformers – in other words, the full metering system. It recommends testing of meters in situ – in substations for system power equal to or above 10 MW every six months, and for loads less than 10 MVA every two years. Meters for consumers with loads of 20 kVA up to 100 kVA should be tested every year; loads above 100 kVA every three, six or twelve months depending on load category; and domestic meters every five years. In addition all instrument transformers must be tested every five years.

Many state regulators have incorporated or are likely to incorporate these requirements in their documents, such as code of supply, grid codes and metering codes.

The National Electricity Policy formulated by the CEA has called for the establishment of third party meter testing facilities by SERCs. Some SERCs have started discussions on how to implement this, but it will take a year or two before some thing concrete emerges out of this guideline.

The Indian Electricity Grid Code draft document released recently has specified special static energy meters (frequency based metering) for use on all interconnection points on the grid.


The National Physical Laboratory (NPL) in New Delhi is the Apex test and calibration laboratory in India. There are several other such laboratories under the control of government departments such as the Ministry of Power and Ministry of Information Technology. Most are accredited to India’s National Accreditation Board of testing and calibration Laboratories (NABL). However, each of them specialises in certain areas and offers services for many types of product. For complete type tests for energy meters it is necessary to go to several laboratories, and waiting time is generally long. These laboratories are equipped to provide calibration of power and energy reference equipment with varying best measurement capabilities and other electrical parameters.

There are only a few laboratories in the private sector, mostly providing calibration services for general purpose instruments or class 1 or 2 energy meters. Only one laboratory in the private sector has Indian (NABL) and international (UKAS) accreditation and provides full type test and calibration services for meters, as well as calibration of instrument transformers and other power and energy reference equipment.

Most utilities operate their own meter test laboratories, which are generally equipped with transformer operated manual or semi-automatic test benches and some portable test instruments. The majority of this equipment comes from local manufacturers. Many laboratories still use old Rotary Sub standards, although a few utilities have modernised in recent times by the introduction of modern automatic test benches and electronic portable test/calibration instruments. These have been supplied by Zera in Germany, MTE of Switzerland, and SML, an Indian manufacturer. The importance of accreditation to NABL has not, however, been fully recognised, and only two or three meter test labs belonging to private utilities are working towards this accreditation. These labs need significant improvement in test equipment, operating conditions, training of staff and overall quality management to boost consumer confidence, and it is a cause for concern that very little is being done to address this.

Instrument transformers (CT and PT), though an important part of a metering system, are rarely tested after installation. Many utilities have some kind of test facilities, but are generally inadequately equipped in terms of either equipment or the manpower and systems to conduct these tests.

The Bureau of Indian Standards also has some laboratories, but they are not equipped to test and calibrate static meters, and the Bureau mainly uses the services of other labs for this. Hardly any meter manufacturer has an NABL accredited calibration laboratory.

Utilities routinely use their own internal meter test labs for inward inspection of electricity meters. However, as part of their buying process some utilities have started to use the services of either their own meter test/calibration labs or external accredited labs for the independent assessment of the quality of sample batches of meters. A subset of type tests is then conducted either before purchase decisions are made or on delivery of the meters. This is certainly a good move, and will help utilities ensure that the meters they have ordered meet quality requirements. Most utilities, however, still prefer to use the services of government labs only. This needs to change – utilities need to recognise and develop confidence in the value of NABL accreditation and give equal opportunity to other labs too.


In the last two years some utilities have awarded service contracts to test installed meters on site, covering tens of thousands of domestic and few hundred industrial consumers. In Delhi, BSES and NDPL, two private distribution companies, have carried out testing of a large number of installed meters, and the test results have led to a decision to replace all their old meters with new static meters. NDPL regularly tests their LIP consumers’ metering systems, and a few other utilities have started similar pilots.

Although it is long overdue, the importance of testing and calibrating electricity meters has been realised. This has generated new opportunities for laboratories, service providers and test equipment suppliers. All of them need to ensure that their services are of the right quality to boost customer confidence and benefits to utilities.