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Calibration & Testing of Electronic Meters


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Presentation regarding training in Metering Equipment Laboratory under Punjab State Power Corporation Limited.

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Calibration & Testing of Electronic Meters

  1. 1. About PSPCL  Punjab State Power Corporation Limited (PSPCL) is the electricity generating company of the Government of Punjab state in India.  It was formerly known as Punjab State Electricity Board (PSEB).  PSPCL was incorporated as company on 16-04- 2010 and was given the responsibility of operating and maintenance of State's own generating projects. The business of Generation of power of erstwhile PSEB was transferred to PSPCL.
  2. 2. Electricity Meters  An electricity meter or energy meter is a device that measures the amount of electric energy consumed by a residence, business, or an electrically powered device.  Electricity meters are typically calibrated in billing units, the most common one being the kilowatt hour [kWh]. Periodic readings of electricity meters establish billing cycles and energy used during a cycle
  3. 3. 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.
  4. 4. 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.
  5. 5. Types of Electricity Meters: There are three types of meters that are currently in the market:-  1. Electromechanical Meters  2. Electronic Meters  3. Smart Meters
  6. 6. 1. Electromechanical Meters  The most common type of electricity meter is the electromechanical induction watt-hour meter.  The electromechanical induction meter operates by counting the revolutions of a non-magnetic, but electrically conductive, metal disc which is made to rotate at a speed proportional to the power passing through the meter. The number of revolutions is thus proportional to the energy usage.
  7. 7. 2. Electronic Meters  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.
  8. 8. 3. Smart Meters  A smart meter is usually an electronic device that records consumption of electric energy in intervals of an hour or less and communicates that information at least daily back to the utility for monitoring and billing purposes.  Smart meters enable two-way communication between the meter and the central system, preventing tampering with the meter.
  9. 9. 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).
  10. 10. 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.
  11. 11. 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.
  12. 12. Continued...
  13. 13. NABL Accreditation  National Accreditation Board for Testing and Calibration Laboratories (NABL) is an autonomous body under the aegis of Department of Science & Technology, Government of India.  NABL has been established with the objective to provide Government, Industry Associations and Industry in general with a scheme for third-party assessment of the quality and technical competence of testing and calibration laboratories.
  14. 14. Testing Bench The testing benches are used to test and calibrate both single and three-phase meters.
  15. 15. Specifications of the Test Bench  Incoming Voltage: 3X230V/400V +/- 10%........65Hz  Outgoing Voltage: 30 to 300V ; 300VA  Outgoing Current: 0.0012 to 120A / 300VA  Maximum Voltage: 300V  Maximum Current: 120A
  16. 16. Parts of Test Bench:-  Scanner  Wires  Reference  Batteries  Emergency Measures  Software Used
  17. 17. 1. Scanner  The SH 11 model scanning head is designed for detection of light emitting diodes (LED’s) of electronic meters. The duration of optical impulse signals from electric meters is detected and evaluated.  The precision optical lens is designed to make the scanning head insensible to external light.
  18. 18. 2. Wires  Red 1- Phase 1 Incoming  Red 2- Phase 1 Outgoing  Yellow 1- Phase 2 Incoming  Yellow 2- Phase 2 Outgoing  Blue 1- Phase 3 Incoming  Blue 2- Phase 3 Outgoing  Neutral- For Earthing purposes
  19. 19. 3. Reference  The meter under test is supplied with a known quantity of the current being calibrated, and the meter is interrogated in order to ascertain the amount of impulses that it has displays.  The amount of impulses is then compared with the reference, and the measurement error is calculated.
  20. 20. 4. Batteries  These batteries are responsible for maintaining constant voltage and current supply across the test benches.
  21. 21. 5. Emergency Measures  A light lamp is attached on top of the bench which signifies whether the bench is working or not.  RED-ON ; GREEN-OFF  This button immediately cuts off the power to the bench, in case of an emergency.
  22. 22. 6. Software Used CAMCAL for WINDOWS is a comprehensive software package designed to fulfil the current requirements of the modern meter testing environment.
  23. 23. Procedure for testing a meter  Mount the meters that are to be tested onto the hooks present on the bench slots. Connect all the wires according to the positions.  Now, align the impulse LED on the meter with the SH-11 impulse scanner.  Turn on the bench and computer. On the desktop, click on CAMCAL software which has been installed as the compatible software to the bench.  In the software, add the meter by filling its properties. Also, select the type of test you want to perform on the meter.
  24. 24. Continued..  After confirming all the specifications of the meter and of the test you want to run are, start the Test.  We can watch the progress of the test being run on the window. The % errors present in all the meter readings are shown alongside their slots. The time remaining for the test to be completed is also shown.  It gives us the specific details about the meter and the % error that is present in the meter’s reading. The data can be exported by clicking on the Export button which will export the data to MS Excel. Now, the results have been exported to the MS Excel.
  25. 25. Some Tests that are conducted on Meters  Scanner Test  100% Imax UPF  100% Ibasic UPF  75% Ibasic UPF  50% Ibasic UPF  25% Ibasic UPF  10% Ibasic UPF  5% Ibasic UPF  100% Ibasic 0.5 lag  100% Ibasic 0.8 lead  Dial Test
  26. 26. Tamper Testing and Security  Electric meters can be manipulated, thus causing them to stop, under-register or even bypassing the meter.  A common method of tampering on mechanical disk meters is to attach magnets to the outside of the meter.  Today, many power companies are installing remote-reporting meters which are capable of detect any tampering in electric meters, and discover energy theft.
  27. 27. Tamper Tests  Voltage Failure  Current Failure  Voltage Unbalance  Current Unbalance  Mobile Tamper Test  Magnet Tampering
  28. 28. What is CMRI?  CMRI is the acronym of Common Meter Reading Instrument.  CMRI is used to download the data of the meter usage from the meter, via a optical data cable.  The data is stored in the memory of CMRI which is send to Lab where the data is analysed and a report is prepared.
  29. 29. Problems Faced  Intensive Heat in Summer  Late Delivery of Calibrated References  Excessive Amount of Meters
  30. 30. Solutions  Using Military Grade ICs  To be calibrated References should be sent to Patiala  Setting up a new NABL Lab in Punjab
  31. 31. THANK YOU Submitted By:- Snehpal Singh