I-DEV0282: Deviation related to the calibration procedures of the energy meters during the monitoring period (09th September 2007 to 22nd June 2009)

The project is undergoing first periodic verification (Monitoring period from 09th September 2007 to 30th November 2008) and the deviation is requested up to 22nd June 2009. The requested deviation is with reference to the calibration frequency of the main energy meter (Make: Secure Meters and Sl. No. WEB18049) at grid substation, which records the electricity exported by the 3 MW hydel power project activity of Neora Hydro Limited (NHL) to the grid interface. The calibration frequency followed for the project activity is done based on local applicable commonly followed practices by State Electricity Board which is different from the EB guidance on calibration (atleast once in three years). Hence as per the guidance specified by the EB (EB 41, Annex 20, para 12) the deviation is being requested.

Deviation Requested:-
According to the guidance issued by EB (EB 41, Annex 20, para 12), for a small scale project, the meters (involved in the monitoring of parameters essential for the computation of emission reductions), need to be calibrated at least once in three years. However, a deviation to the required calibration frequency has taken place in which the meter has been calibrated after a period of 3 years, 9 months and 18 days from the first calibration. Instead, the WBSEDCL (West Bengal State Electricity Distribution Company Limited), the state level government electricity authority which has sole authority to calibrate the main energy meter installed at grid substation as per the agreed upon terms of the Power Purchase Agreement (PPA) has performed regular in-site tests of the corresponding meter from time to time (in the period 03.09.2005 to 03.09.2008) to ascertain its accuracy. This in-site testing is an inherent feature of WBSEDCL’s calibration practices (local calibration standards followed for all meters owned by WBSEDCL) and the same has been accordingly followed for the case of the project activity as well.

Reason for deviation:-
As per the electricity monitoring pattern observed in grid connected renewable energy projects in India, the electricity monitoring is governed by the Terms and Conditions as mentioned in the Power Purchase Agreements (PPA) signed with the respective State Electricity Board. As commonly observed, the electricity supplied to the grid is being monitored through a set of energy meters (Main meter and Check meter) installed at the grid interface. These energy meters are owned and under sole control of respective electricity authority. As per the conditions of the PPA project participants can not intervene into this metering process. The periodic testing and calibration of the energy meters are taken care of by the grid authority, West Bengal State Electricity Board. The PPA agreed upon between the project participant, NHL and WBSEDCL categorically specifies (PPA – Section 5.0: Metering arrangement, clause 5.5) that the said meter at Chalsa Substation would be owned, maintained and calibrated periodically solely by WBSEDCL. The PPA does not mention any specific calibration frequency. In line with this provision in the PPA, the project participant had proposed corresponding Monitoring Plan in the PDD during validation and the same was accordingly validated by the DOE based on the Terms & Conditions mentioned in the PPA. But, thereafter, a guidance (EB 41, Annex 20, para 12) was issued by the EB, making it mandatory for calibration of meters of project activities atleast within a period of three years.
Therefore it is requested that the EB allows the project activity deviation of non conducting the calibration of main meter within the 3 years of first calibration as per EB 41, Annex 20, para 12 for the monitoring period from 09th September 2007 to 30th November 2008 and up to the next calibration done on 22nd June 2009. After 22nd June 2009, this deviation for calibration is not applicable.

The indicated deviation in calibration frequency of energy meter for the current monitoring period 09th September 2007 to 30th November 2008 and up to 22nd June 2009 when calibration was conducted. This deviation neither require a revision of registered monitoring plan nor involves changes in project activity description as mentioned in the registered PDD.

There has not been any loss of accuracy despite the meter not being calibrated within 3 years. This has been certified by the government agency WBSEDCL. Moreover it is also evident from the following observations made by the DOE during verification:

(a) Initial test certificate issued by Secure Meters Ltd to West Bengal State Electricity Board dated 18/07/2005 confirms accuracy.

(b) Accuracy test report of energy meter, dated 03/09/2005; issued by West Bengal State Electricity Transmission Company Limited ensures accuracy of the energy meter during the time of commissioning.

(c) WBSEDCL has, as a part of its standard practices, been regularly testing the accuracy of the meters by conducting regular in-situ tests. WBSEDCL has not found any loss of accuracy throughout the verification period. The Addl. Chief Engineer, WBSEDCL in a letter (ref. no. C/BP/Neora Hydro Ltd.2221A; dated 01/07/2009) has endorsed that the grid authority has carried out the in-situ test of the main meter (s/n. WEB18049) periodically inbetween the period 03/09/2005 to 03/09/3008 and no malfunctioning and discrepancy has been detected. The same letter from WBSEDCL also mentioned the detailed procedure followed for in-situ testing of the main energy meter. As part of its standard practice, WBSEDCL calibrates only those meters in which some inaccuracies are found during in-situ testing. For the project activity meter, since no inaccuracy was found during in-situ testing, WBSEDCL did not deem it necessary to perform a calibration.

(d) The main energy meter (Make: Secure Meters Limited; Type: E3V055, Class: 0.5, Serial No. WEB18049) deployed at the grid substation has not been replaced since commissioning of the project activity and still under operation during the current monitoring period.

(e) On a special request from the project participant, the WBSEDCL has performed a calibration of the meter on 22/06/09 (after 3 years 9 months and 18 days from earlier calibration) and has found the meter to be without any inaccuracy. The calibration certificate of the main energy meter (s/n. WEB18049) issued by WBSETCL (Ref. STC/Tech/3/144; dated 23/06/2009) confirms the accuracy of the energy meter and error within permissible limits as per CBIP & IEC 689. This clearly justifies that the meter was operating absolutely accurately from 03/09/05 till 22/06/09 which includes the concerned verification period which is used to ascertain the accuracy of any meter.

The above mentioned substantiations justify the accuracy of the energy meter during the current monitoring period.

The non calibration of the main energy meter during the period 03/09/2005 to 22/06/2009, does not affect the level of accuracy of emission reduction calculation. The TOD main meter readings form the basis of the monthly Joint Meter Report (JMR) statement signed by the officials of WBSEB and NHL. This procedure was found consistent with the metering arrangement provisions of Power Purchase Agreement dated 24/11/2006. The emission reduction calculation is done based on the net electricity export readings monitored through main meter installed at grid substation. The electricity export data is being registered in daily log sheets and the monthly data for the parameter forms a basis for a Joint Meter Reading (JMR) Statement duly signed by the authorised signatories from project participant and the state grid authority. The joint meter reading statements for the current monitoring period has been cross checked and no evidence on malfunctioning of the main energy meter was found to have been reported.


The monthly JMR statement data in turn forms the basis of power invoicing, the monthly power invoices based on which WBSEB pays to project participant. The monthly JMR statement data and the monthly power invoice data related to power export to the grid were found consistent with those in the CER calculation sheet for the monitoring period requesting deviation. The government agency (WBSEDCL) purchasing power from the project activity has continuously made payments according to the readings of the meter (despite no calibration within 3 years). This clearly demonstrates that the readings are accurate as financial transactions are based solely on the accurate energy reading values.

Hence, the requested deviation with respect to calibration frequency does not compromise on accuracy of the emission reduction calculation for the current monitoring period 09th September 2007 to 30th November 2008 and up to 22nd June 2009.