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
2
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...
3
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...
4
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.
5
CONCEPT OF AT&C LOSSES
TECHNICAL 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...
6
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...
7
CONCEPT OF AT&C LOSSES
COMMERCIAL LOSSES

Factors causing Commercial Losses:
 Discrepancy in Meter Reading
o Untraceable consumers
o Stopped/defective meters
o Temporarily disconnected consumers continuing in
billing solution
o Premises found locked
Contd...
8
CONCEPT OF AT&C LOSSES
COMMERCIAL LOSSES

Factors causing Commercial Losses:
 Metering
o
Meter tampering
o
Bypassing of meters
o
Usage of magnets to slow down the meters
o
Tampering of PT circuits
o
CT/PT ratios (in case of HT meters)
Contd...
9
CONCEPT OF AT&C LOSSES
COMMERCIAL LOSSES
 Factors causing Commercial Losses:

Theft by direct hooking
o Tapping of LT lines to indulge in theft through
direct hooking
o Sometimes even drawing an underground cable
direct from Distribution Transformer
Contd...
10
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.
11
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...
12
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
LILO/tie lines.
meters
on
33/11
kV
sub-stations
Contd...
13
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...
14
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...
15
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.
16
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
commission
(SERC)
by
for
respective
state
assessment
of
regulatory
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...
17
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
18
COMPUTATION OF AT&C LOSSES
19
THANK YOU
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