Presentation on ELECTRICITY DISTRIBUTION LOSSES & CONCEPT OF AGGREGATE TECHNICAL AND COMMERCIAL (AT&C) LOSS R.V. Shahi Former Power Secretary, Govt. of India Chairman of Energy Infratech Pvt. Ltd. (November, 2011)

CONTENTS Anomalies in T&D Loss Computation Concept of AT&C Losses Pre-requisites for obtaining baseline AT&C losses Methodology for establishing AT&C Losses for Project Area Sample Calculation for Baseline AT&C Losses

ANOMALIES IN T&D LOSS COMPUTATION In Indian Power Sector, T&D Losses, as computed in the past, over several decades, never represented the true picture about losses in the system. Similar is the situation in a number of developing countries. The Method & Procedures enable manipulations in computations. The functionaries (Officers & Staff) could present a good picture to reflect their efficiency, while the ground reality could be different. Contd...

ANOMALIES IN T&D LOSS COMPUTATION In absence of feeder metering separating Agriculture & Domestic Consumption, substantial portion of T&D loss, including theft of electricity, gets attributed to agricultural consumption. Also, T&D loss was being computed taking into account electricity bills issued to consumers as accrued income & not on actual collection. Contd...

ANOMALIES IN T&D LOSS COMPUTATION Just by overbilling, one could show a much lower than actual loss. Therefore, T&D loss figures did not capture the major gap between the Billing and the Collection, apart from large amount of theft. Theft and deliberate manipulations by staff get subsumed in excess Billing (Which would obviously never get collected) To get over this problem, concept of Aggregate Technical & Commercial (AT&C) loss was introduced.

TECHNICAL LOSSES CONCEPT OF AT&C LOSSES Factors causing Technical Losses: Transformation Losses (at various transformation levels) High I2R losses on distribution lines due to inherent resistance and poor power factor in the electrical network Inadequate Planning & Design, irresponsible overdrawals by Consumers Overloading of existing lines and substation equipments Absence of upgradation of old lines and equipments Low HT: LT ratio Contd...

CONCEPT OF AT&C LOSSES TECHNICAL LOSSES Factors causing Technical Losses: Poor repair and maintenance of equipments Non-installation of sufficient capacitors Requirements for calculating Technical Losses: 33 kV and below HT network Line Diagrams Line Diagrams for each of distribution transformers and LT circuits upto poles/feeder pillars Voltage levels, Power factor and Current loading on HT/LT network & network equipments Line lengths, cross section & nature of material, network equipment’s load curve etc Contd...

CONCEPT OF AT&C LOSSES COMMERCIAL LOSSES Discrepancy in Meter Reading Factors causing Commercial Losses: Discrepancy in Meter Reading Untraceable consumers Stopped/defective meters Temporarily disconnected consumers continuing in billing solution Premises found locked Contd...

CONCEPT OF AT&C LOSSES COMMERCIAL LOSSES Metering Factors causing Commercial Losses: Metering Meter tampering Bypassing of meters Usage of magnets to slow down the meters Tampering of PT circuits CT/PT ratios (in case of HT meters) Contd...

CONCEPT OF AT&C LOSSES COMMERCIAL LOSSES Factors causing Commercial Losses: Theft by direct hooking Tapping of LT lines to indulge in theft through direct hooking Sometimes even drawing an underground cable direct from Distribution Transformer Contd...

CONCEPT OF AT&C LOSSES COMMERCIAL LOSSES Collection efficiency Utility is not being able to collect the complete amount billed by it. Absence of Energy Accounting & Auditing In case of unavailability of arrear figures, the collection efficiency figures can be more than 100%. Revenue collected shall exclude the arrears. In above cases efficiency needs to be restricted to 100% and shall be used for computation of AT&C losses.

PRE-REQUISITES FOR OBTAINING BASELINE AT&C LOSSES Metering of Energy Input Points of Project Area On incoming lines of 33/11 kV sub-stations located within project area. On 33 kV, 11 kV feeders emanating from sub-station located outside project area but supplying power to HT/LT consumers located within project area. Contd...

PRE-REQUISITES FOR OBTAINING BASELINE AT&C LOSSES Ring-fencing of Project area electrical network Import/export meters at the boundary of those lines that are feeding outside as well as inside project area so that import and export of energy can be measured for project area. These lines may emanate from the sub-stations located within or outside project area. Import/export meters on the dedicated feeder emanating from sub-stations located within project area but feeding outside project area. Import/export meters on 33/11 kV sub-stations LILO/tie lines. Contd...

PRE-REQUISITES FOR OBTAINING BASELINE AT&C LOSSES Segregation of Rural Loads within Project Area For HT (11kV) feeders, providing power to mixed category of consumers including agricultural (rural), commercial, domestic etc., within project area, utilities may segregate these feeders through installation of separate HT feeder for such loads. Contd...

PRE-REQUISITES FOR OBTAINING BASELINE AT&C LOSSES Billing & Revenue Collection System Billing system is to be able to provide data like sales, revenue billed and collected for entire project area. The current billing system is designed in a way that sale data can be extracted for 11 kV feeder or for distribution centers (DCs) as whole. Utilities to make provisions to account for sales happening outside project area. Contd...

PRE-REQUISITES FOR OBTAINING BASELINE AT&C LOSSES Computation of Input Energy To install meters at input points of each of feeders (66 kV, 33 kV, 11 kV etc.) and read them at pre-defined intervals. In case of LILO, net input energy to the project area of the feeder shall be considered. If 66 kV or 33 kV feeder is directly feeding to a dedicated consumer and that consumer(s) is within project area, input of such feeder shall be considered as part of input energy to the project area.

METHODOLOGY FOR ESTABLISHING AT&C LOSSES FOR PROJECT AREA Computation of Sales The billing for metered consumers can be done through energy recorded by meters and the applicable tariff. In case of unmetered consumption Norms established by respective state regulatory commission (SERC) for assessment of unmetered consumption. In case SERC norms are not defined, a consumption of 150 (Units) kWh for each 1 kW of sanctioned connected load. The assessment is allowed only for limited period of time and the utilities are required to complete 100% metering within 6 months. Contd...

METHODOLOGY FOR ESTABLISHING AT&C LOSSES FOR PROJECT AREA Computation of Billing Efficiency Billing Efficiency = Total Units Sold (kWh) Total Input (kWh) Computation of Collection Efficiency Collection Efficiency = Revenue Collected (in Naira) Billed Amount (in Naira) Computation of AT&C Losses AT&C Losses = {1-(Billing Efficiency x Collection Efficiency)}x100

COMPUTATION OF AT&C LOSSES

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