Metering & Data Processing. 1. WHAT IS METER ? A device which measures, indicates and records certain measurable quantity. 2. WHAT IS ENERGY METER ? A device which measures, indicates and records electrical power flow (energy) in a specified time between two points.
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A device which measures, indicates and records certain measurable quantity.
2. WHAT IS ENERGY METER ?
A device which measures, indicates and records electrical power flow (energy) in a specified time between two points.
3. Pre Requisites of a Meter
Purpose : Catering to Commercial needs
Futuristic : Catering to forceable needs
Reliable : Repeatability
Accurate : Good amount of money at stake
Installed at interconnecting points between
2. ConsumerMeter :
Electrical utility to consumer not covered under INTERFACE meters
3. Energy Accounting and Audit Meters :
Used between Gen Stns to different segments of electrical system determines
Our focus is on SEMs which are interface meters
SEM is an Application specific Microprocessor base solid state energy meter. This together with a data collecting device (DCD) and a local Computer forms a powerful system of metering and data logging.
This arrangement of metering and data logging gives a unique method for measurement of all relevant electrical quantities.
ABT, three part tariff :
Total payment for the day = a + b (+/-) c
Reason of metering
Its a challenging task for the utilities due to huge volume of data logged by these meters
Initial/one time activities
SEMs are of following two types :
A-TYPE : Connected to VT having rated secondary line-line voltage of 110V and CT having rated secondary current of 1A.
B-TYPE: Connected to VT having rated secondary line-line voltage of 110V and CT having rated secondary current of 5A.
It operates with power drawn from the secondary circuits and no auxiliary power supply required.
a) Analog Section: High precision Current transformer and voltage transformer step down input currents and voltages which are fed to an Analog to Digital converter.
b) Digital Section: A powerful microprocessor controls the Analog and Digital sections. Analog to Digital converters are fed from high precision instrument transformers. The Digital samples from Analog to Digital converter are used to process the metering data. The sampling rate is 3000 samples per second which gives the meter an exceptional accuracy and results.
c) Power supply Section: A switch mode power supply (SMPs) unit supplies power to the meter’s internal circuit.
Display Parameter Indication Display format
Meter identification code A NP1234A
Date (day, date, month, year) d dd-mm-yy
Time (hour, min, sec) t hh:mm:ss
Cumulative Wh reading c xxxx.x Wh
Reactive Power Pr xxx:x VAr
Average freq. of previous block F xx:xx
Net Wh transmittal-previous block E xx:xx
Average % voltage U xx:xx
Voltage high VArh register reading H xxxx:x VArh
Voltage low VArh register reading L xxxx:x VArh
Real time indication rtC Fit
Low battery indication Low Bat
Philosophy of installation
Out going feeders
400 KV BUS
Main meter is provided on EHV side of ICT and stand by meter on LV side of ICT.
400 KV BUS
STAND BY METER
220 KV BUS
For Inter-state lines.
STAND BY METER
STAND BY METER
On POWERGRID lines, unless an end is regional energy accounting point, an Energy Meter is provided only at one end of each line. The readings recorded by these meters are being used for information and analysis only, and not for the energy accounting purposes.
Actual freq = 49 + ( 2digit code / 50 )
e.g. If, SEM shows 2 digit code of 55 as frequency code,
The actual frequency = 49 + (55 / 50) = 50.1 Hz
( V > 103% of Rated Voltage)
(V < 97% of rated Voltage)
DCD is a hand held terminal, capable of communicating with SEM as also with PC. Both communication requires suitable software at both DCD and SEM
Conventional data collection method for past 12 years.
DCD with Optical Cord
Optical port in SEM
Validation of SEM data
Identification of any metering error can be done through three broad categories of checks.
Checks are also carried out to ascertain time drift in the meters with reference to Master meter.