Energy Meters

ENERGY METERS
Dr A K TIWARI
ashokktiwari@gmail.com

What is energy ?
• Energy is the total power consumed over a time interval, that is
Energy = Power × Time.
• Generally, the process of measurement of energy is same as that
for measurement of power except for the fact that the instrument
used should not merely measure power or rate of consumption of
energy, but must also take into account the time interval during
which the power is being supplied.
• The unit of energy can be expressed in terms of Joule or Watt-
second or Watt-hour as per convenience. A larger unit that is most
commonly used is kilowatt-hour (kWh), which is defined as the
energy consumed when power is delivered at an average rate of 1
kilowatt for one hour.
• In electricity utility metering, this amount of 1 kilowatt-hour (kWh)
energy is specified as 1 unit of energy.

Demand and Energy

History of Electricity Meters
• Samuel Gardiner takes out the first known patent on an
electric meter in 1872. This was a DC lamp-hour meter
that was a clock with an electromagnet that started
and stopped the mechanism.
• Thomas Alva Edison, who introduced the first electrical
distribution systems for lighting using direct current,
held that electricity must be sold just like gas – also
used extensively for lighting at that time. His “Electric
meter” patented in 1881, used the electrochemical
effect of current.

Continued…
• Oliver Blackburn Shallenberger developed an
induction type watthour meter for
Westinghouse in 1894, which is reminiscent of
modern day meters.
• Shallenberger and an assistant accidently
discovered this. While working on an AC arc
lamp, a spring fell and they realized that the
spring had rotated. Shallenberger eventually
discovered that the changing electric fields
induced a magnetic field which caused the
metal spring to rotate.

Conventional
meters
• Meters conventionally
measured a single
quantity
– – kWh
– – kVArh
– – kVAh
• Meters were used for
commercial purpose,
(record consumption
and bill to consumer)
Earlier
called
trivector
meter

SINGLE-PHASE INDUCTION-TYPE
ENERGY METER

• 1. The torque is directly
proportional to the power
factor of the aluminum disc
(cos β). Thus, to increase the
deflecting torque, the path of
eddy current in the disc must
be as resistive as possible, so
that value of cos β is as high
as possible.
• 2. The torque is directly
proportional to sin α.
Therefore, to have large
deflecting torque, the angle α
between the two fluxes
should preferably be as
nearly as possible close to
90°.

• 1. Voltage coil–many
turns of fine wire
encased in plastic,
connected in parallel
with load.
• 2. Current coil–few
turns of thick wire,
connected in series
with load
• 3. Stator–concentrates
and confines magnetic
field.
• 4. Aluminum rotor
disc.
• 5. Rotor brake
magnets
• 6. Spindle with worm
gear.
• 7. Display dials

Parts of energy
meters

• Thus, total number of revolutions is proportional to the energy consumed.

ERRORS IN INDUCTION-TYPE ENERGY
METERS
• Phase-angle Error
• Error due to Friction at Light Loads
• Creeping Error
• Error due to Change in Temperature
• Error due to Overload
• Error due to Voltage Variations

Principal of energy measurement
• In energy meters, the number of pulses are
proportional to the energy consumed.
CT PT
Timer
ADC
Processor
Processor Pulse
Generator
comparator
Counter
and
registers
Display

TYPES OF METERS
Energy meter
1 phase 3 phase
Whole
current meter
CT Meter
Energy Meter
LT Meter
1 phase
3 phase
HT Meter
3 phase CT
Special
Purpose meter
Prepaid meter
Summation
meter
LPR Meter
Smart Meter
ABT Meter

Special purpose meter
• Prepaid meter
• Summation meter
• LPR Meter
• Smart Meter
• ABT Meters

MAXIMUM DEMAND

Methods of MD Calculation
• Block method
• Sliding window method
Integration

SUMMATION METRING

What is written on meter ?
LOOK

SPECIFICATION
• PHASE
• WIRES
• VOLTS and Freq
• CURRENT RATING
• IMP/KWH
• ACCURACY CLASS
• MAKE and TYPE
• SR NO
• YEAR
• PROP
• IS 13779

Meter connection

LOCATION OF ENERGY METER
CALL BELL LOCATION

WHAT IS MISTAKE ?

SINGLE PHASE METER

3 PHASE CT Meter

Connection diagram 3 ph CT meter
R
Y
B
N

CT METER BOX
METER
CTs

Push Fit Meter Box are made of polycarbonate material. These
meter boxes are durable and rust proof. Self locking

• Accuracy class of the meter is written on meter name plate as CL 1.0 or CL
0.5 or CL 0.2 :
Class 1.0 - having ± 1 % accuracy.
Class 0.5 - having ± 0.5% accuracy.
Class 0.2 - having ± 0.2% accuracy
DOMESTIC Meters are CL 1.0 . if the monthly consumption is 300 units it
means actual consumption is between 297 and 303 units (± 1 %)
multiplying factor of meter MF=
(ACTUAL PT ratio x ACTUAL CT ratio x meter constant or dial factor) /
(meter PT ratio x meter ct ratio)

Electronic Energy Meter
• Electronic Energy Meter is based
on Digital Micro Technology
(DMT) and uses no moving parts.
• In EEM the accurate functioning is
controlled by a specially designed
IC called ASIC (Application
Specified Integrated Circuit). ASIC
is constructed only for specific
applications using Embedded
System Technology.

COMPONENTS OF ELECTRONIC
ENERGY METERS
• Registers ,
• electronic counters,
• universal counters,
• Comparators,
• Gate generators,
• visual read out system - LED or LCD display
• Logic circuits
• A/D and D/A Convertors

Registers
• The Shift Register is
another type of sequential
logic circuit that can be
used for the storage or the
transfer of data in the form
of binary numbers.
• This sequential device
loads the data present on
its inputs and then moves
or “shifts” it to its output
once every clock cycle,
hence the name “shift
register”.

Basic Data Movement Through A Shift
Register

counters

Comparators
• The comparator is an electronic decision making circuit that makes use of an
operational amplifiers very high gain in its open-loop state, that is, there is no
feedback resistor. The Op-amp comparator compares one analogue voltage level
with another analogue voltage level, or some preset reference voltage, VREF and
produces an output signal based on this voltage comparison. In other words, the
op-amp voltage comparator compares the magnitudes of two voltage inputs and
determines which is the largest of the two.

ADC and DAC

ANALOG TO
DIGITAL
CONVERTOR

DIGITAL TO ANALOG CONVERTOR

visual read out system
• LED
• LCD display

LED Display

LCD Display

Prepaid Energy Meter
• A scheme of Electricity billing system called PREPAID ENERGY METER WITH TARIFF
INDICATOR can facilitate in improved cash flow management in energy utilities and
can reduces problem associated with billing consumer living in isolated area and
reduces deployment of manpower for taking meter readings.
• Every consumer can buy a memory card (is nothing but an EEPROM IC) with a
password stored inside it using a MC program. The memory card is available at
various ranges (ie. Rs 50, Rs 100, Rs 200 etc).
• When the consumer insert a smart card into the card reader which is connected
kit. Then the card reader will read the stored information and delete the
information from the EEPROM IC(smart card) using the MC program. So that the
smart card cannot be reused by others.
• Suppose if a consumer buy a card for Rs.50/- he / she can insert this amount
through the card reader so that prepaid energy meter with tariff indicator kit will
be activated. According to the power consumption the amount will be reduced.
• When the amount is over, the relay will automatically shutdown the whole
system. In our project we also have a provision to give an alarm sound to
consumer before the whole amount is reduced.

Main Advantages
• It is highly accurate as the whole idea of reading the units
and then billing manually or any other means is eliminated.
• Consumer cannot escape from paying the electricity bill
and the State Electricity Board gets free from debts.
• On the consumer front, the tedious task of paying the bill
and waiting anxiously for the bill is eliminated.
• Wastage of energy is diminished as now only the required
energy will be consumed as allotted.
• The utility can monitor the overall energy consumption and
any tampering attempts are actually of no use and can be
detected if still prevalent.

Block Diagram of Prepaid Energy Meter

Radio
• 3 KHz to 300 GHz
• Economical media of communication
• Radio transmitter and receiver
• Modulation- AM , FM, PM
• Metering band : 865 KHz or 2.4 GHz in India
• Disadvantages:
– Hazardous to health
– Limited range
– Effected by climate
– Obstructed by high rise building and hills

Low Power Radio METER

Used as Wireless Communication for
Low Power Radio Frequency
• Energy Meter based on IEEE 802.15.4G.
• Ability for network to dynamically change channel if
interference arises for long term.
• Centralised data collection system.
• Each meter aids transfer of data for self as well as
neighbouring Meters.
• Automated device address management.
• Group addressing.
• Efficient in terms of power consumption versus range
performance.
• Reliable, Economical and interoperable solution for
utilities.
• Support for bidirectional exchanges.
• Network scalability feature simplifies network
development even allowing multiple networks to co-
exist.
• Wireless Commissioning.
• Software solutions for communication also available
• kWh, MD in kW with Date & Time, Six Months History of
Energy
• 5-30A,10-40A
• Applicable Standards:IS13779 : 99, CBIP Technical Report
88

METERING TOPOLOGY

DATA SHARING

Zigbee
Wireless communication technology
Low power
Low cost
Less size
Mesh networking
Self healing
Very low wakeup time

IrDA
• Invisible radiant energy
• EM waves with freq from 300GHz to 430THz
• Wavelength : 700 nm to 1 mm
• Infrared LED at transmitter
• Infrared sensor at receiver
• Range – 10 meter or 30 feet
• LINE OF SIGHT required

infrared meter

Allocated spectrum
• 0 - 500 KHz for narrowband PLC
communications
• 2 MHz - 200 MHz for broadband PLC
communications
• 865-867 MHz low power RF devices
• 10-12 MHz for low power RF devices.

Optical port

MODEM
• Short for MOdulator-DEModulator.
• A modem is a device or program that enables
a computer to transmit data over, for example, telephone
or cable lines.
• Computer information is stored digitally, whereas
information transmitted over telephone lines is transmitted
in the form of analog waves.
• A modem converts between these two forms.
• Some modems perform data compression, which enables
them to send data at faster rates. However, the modem at
the receiving end must be able to decompress the data
using the same compression technique.

Meter data acquisition by MODEM

DATA CONCENTRATOR UNIT (DCU)
• It is an intelligent device , acquire data from
MIU . It has built-in GSM/GPRS Modem to
transmit data to data acquisition server
interfaced with data logger PC.
• DCU- supports CDMA & GPRS , MIOS
/MODBUS/DLMS , IP based communication,
VPN Real time temper /outage alert . Two way
communication
• MIU – Meter Interface units

DATA CONCENTRATOR UNIT (DCU)

RS 232
and
RS 485
serial
interfaces

GSM BASED AMR

GPRS based MDAS

Interoperability Standard for Energy
Meters in India

MIOS
• Interoperatability standard to allow seamless communication /exchange of
data from these meters and applications software like billing , load profile
analysis etc irrespective of the make (protocol) of the meter.
• For existing proprietary protocol meter will provide an executable plug-in
dll file that can be called by any third party common framework.
• The executable dll /API will –
– Reading of the meter data (from storage)
– Check security
– Interpret (decode)
– Provide data (transfer data) in common agreed data format
• Meter manufacturer make API available to all utilities and all system integrates

STANDARIZATION OF METERING
PROTOCOL
• ANSI and IEC Standards
• India follows IEC
• IEC-62056 DLSM/COSEM Specs
– IEC Standard meter TC-13
– CPRI –ET-13
– BIS-ETD-13 (IS 15959-2011)

DLSM and COSEM
• Device language message specification
• Companion specification for energy metering
• 131 countries are member

Indian standard DLMS meter
• IS 15959-2011
• Data exchange for electricity meter , reading , tariff and load
control companion specification
• CPRI has testing and certification facilities

Types of meter data
1. Instantaneous
parameters
2. Block profile /load
survey data
3. Accounting /billing data
4. Abstract Quantities
• Name plate details
• Programmable
parameters
5. Event / temper
conditions

Instantaneous data
• Date and Time from real time clock
• I-Current RYB
• V-Voltage RN, YN, BN
• Frequency
• Power Factor
• KW, KVAr, KVA

Block profile /load survey data
• Capture time – block -15 or 30 minutes and days
• Avg Current RYV
• Avg Voltage RN , YN, BN
• KWh
• KVArh
• KVAh

ACCOUNTING / BILLING DATA
• KWh
• KVArh (lag , lead)
• Max demand in KW
• Max demand in KVA
• Power Factor
• Cumulative data
• In different TOU

Abstract data
• Name plate details of meter- manufacturer
name, meter sr no. , version of meter and
software
• Internal CT and PT Ratio
• Programmable parameters
– Clock
– Demand integration period
– Time zone TOD
– Schedule of billing and tarriff

EVENT or TEMPER DATA
• Meter cover opening
• PT Link missing –RYB
• o/v u/v in any phase
• Voltage unbalance
• CT Reverse RYB
• CT Open RYB
• O/C in any phase
• Influence of AC/DC or Magnet
• Neutral disturbance
• Very low p.f.
• Power failure

METER PROTOCOL TESTING
• Checking of protocol if it is working as per
standard . It includes testing of functionality,
performance, scalability, protocol algorithm
and interoperatibility.
• Three checks are done –
– correctness
– Latency ( transit time of one data packet)
– Bandwidth ( no of data packets per second)

METER PROTOCOL TESTING
• Three categories of protocol testing
– Conformance testing (as per standard- correctness of protocol)
– Network feature test (latency and bandwidh)
– Interoperatability testing (with equipments of different venders)
Protocol testing requires two systems -
1. Protocol Analyzer - decodes the protocols
2. Simulator – simulates various conditions of network entities
In India Meter Protocol testing is done by CPRI

Protocol Testing Tools - SCAPY , WIRESHARK

DATA SECURITY IN METERS
• Data access control
mechanism
– Basic security -
Authentication
– Advance level security-
Encryption ,
Authentication
Low level security at
utility level – password
based , Utility setting
High level security – 4
pass sign on ,
encryption, secret key
Confidentiality
IntegrityAuthentication

Spot billing
Spot Billing system is a system, in which the meter reader visits the
consumer’s premises, records the meter reading and issues the bill
on the spot using a hand-held computer/Simputer

SPOT BILLING

TESTING OF ENERGY METERS
• To find out the errors in the measurement of
energy by the meter at different conditions of
load and power factors
• It compared with portable substandard energy
meter called ESS
• The ESS is periodically tested and pre-
calibrated through standard meter in govt
approved accredited testing laboratory

What is Calibration?
• Calibration refers to a process of verifying the performance of
any instrument that measures, sources or tests some
parameters.
• Electrical calibration involves the use of precise devices,
known as standard, that evaluate the performance of key
properties for other devices called Units Under Tests (UUTs).

Why is Calibration necessary?
• To ensure readings from an instrument are consistent with
other measurements.
• To determine the accuracy of the instrument readings.
• To establish the reliability of the instrument i.e. that it can be
trusted.

Calibration Process
• A known amount of energy is simultaneously supplied to
a reference meter and to the unit under test (UUT).
• A reading from the reference meter is then compared to
a reading from the UUT and the error is calculated.

Continued...

Equipments required for energy meter
testing
1. Portable ESS
2. Phantom loading kit
3. Stop watch or Timer
4. Wires and connectors for connections

Test setup

Phantom Loading
• When the current rating of the meter under test is high, a test with actual loading
arrangements would involve considerable wastage of energy and also it is difficult
to arrange for such large loads under laboratory test conditions.
• In such cases, to avoid this, ‘phantom’ or ‘fictitious’ loading arrangements are
done for testing of energy meters.
• Phantom loading consists of supplying the shunt magnet pressure coil circuit from
a rated voltage source.
• The series magnet current coil is supplied from a separate low voltage supply
source. It is possible to circulate rated current through the current coil circuit with
the low voltage source since impedance of this circuit is very low.
• The energy indicated by the meter under phantom loading condition is the same
as the energy indication as would have been with a real load. With this
arrangement, the total energy consumed for the test is comparatively smaller.
• The total energy required for the test is that due to the small pressure coil current
at rated voltage and small current coil voltage at rated current.

A 220 V, 10 A dc energy meter is tested for its name plate ratings. Resistance of the pressure coil circuit is 8000 Ω and
that of current coil itself is 0.12 Ω. Calculate the energy consumed when testing for a period of 1 hour with
(a) Direct loading arrangement (b) Phantom loading with the current coil circuit excited by a separate 9 V battery
Thus, energy consumed is considerably less in phantom loading as compared to direct
loading for energy meter testing

Meter testing at MPPKVVCL
• At region : HT MT Division
• At Circle level : LTMT Lab under STM Division

LT MT LAB

Accuchek
• It is desirable to test meters and associated equipment
periodically in service.
• Accuchek is in-field energy meter test equipment. The
rugged portable units house a high-precision master
meter with an integral computational unit for meter
errors and a full set of connecting leads and probes.
• Commissioning checks for new energy meter
installations
• Error testing and routine in-service testing of energy
meters
• Revenue protection investigations
• Investigating consumer metering error complaints

• High accuracy (class 0.2s with ring-type CT, or class 0.5s in clamp-on mode)
• Suitable for LV/MV/HV testing
• On-site testing of meter without disconnecting the load
• Compatible with all electronic or electro-mechanical meters
• Suitable for different types of meter
• Optical sensor works with LEDs or rotating disc indicators
• Automatic testing of electronic meter with metrology pulse LED
• Testing of electromechanical energy meters with rotating disc indicators
• Displays the percentage error of the meter under test
• Displays the error result directly for meter under test
• Large LCD backlit display for easy viewing
• Displays a range of instantaneous electrical parameters
• Shows voltage, current and power parameters, as well as energy, for quick
verification of installation
• Extensive data storage for test results
• Non-volatile memory for up to 200 test results

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