P-E-01—Procedures for calibrating and certifying electricity meter calibration consoles pursuant to EL-ENG-12-01—Requirements for the certification of measuring apparatus—electricity meter calibration consoles

7.0 Procedures for the assessment of metrological requirements
(EL-ENG-12-01, s. 7.0) (part 3 of 4)

7.4 Variation from position to position (EL-ENG-12-01, s. 7.4)

7.4.1 Purpose

The purpose of section 7.4 of EL-ENG-12-01 is to ensure that the spread of errors between MUT positions of a console does not exceed the specified tolerance. The errors at each position must also comply with requirements of sections 7.8.1.1, 7.8.1.2 and 7.8.1.3 pursuant to EL-ENG-12-01.

7.4.2 Guidelines

In this test, an error is established for each MUT position by following the basic procedure described in section 7.3 of this document. This assessment is only applicable to consoles used with the setups identified in 7.3.4.2(3) (c) and (d) above. The console shall be calibrated at each MUT position using the burden determined pursuant to 7.3.4.6 or 7.3.4.7 above at the applicable test load with similar burdens connected in each other MUT position.

7.4.3 Procedure for consoles intended to test polyphase transformers-type meters or polyphase self-contained meters only

  1. Install burdens (meters) in all but one position.
  2. Install the test socket in the empty position.
  3. Connect the certified standard and the comparator, and align the light valve following the test setup procedures in section 7.3 of this document.
  4. Connect the polyphase test burden and load as determined by the requirements of section 7.3.4.2(3) (c) above.
  5. Begin testing by following the test procedure in section 7.3 of this document.
  6. Read the apparent error of the standard at the MUT position on the console display and record it on the calibration worksheet.
  7. Repeat steps (5) and (6) above for each MUT position.
  8. If the console is only used for the verification of polyphase self-contained meters, only perform the above procedure with the applicable test burden and load as determined by the requirements of section 7.3.4.2(3) (d) above.

7.4.4 Remarks

The tolerance for the spread of errors determined in the procedures above is specified in section 7.4.1.1 of EL-ENG-12-01. All measured errors in the procedures above are also required to be within the tolerances of the applicable parts of section 7.8 of EL-ENG-12-01.

7.5 Distortion (EL-ENG-12-01, s. 7.5)

7.5.1 Purpose

The purpose of section 7.5 of EL-ENG-12-01 is to ensure the level of distortion measured on the current and voltage circuits used to energize meters is within the tolerance pursuant to EL-ENG-12-01.

7.5.2 Guidelines

The tests of this procedure are conducted with current and voltage circuits simultaneously energized, and the appropriate burdens installed in each of the MUT positions, unless otherwise stated. These tests are conducted with regulators and line conditioners switched out of the circuit (if normal metering tests are performed without regulators or line conditioners) and also with regulators and line conditioners switched into the circuit (if those devices are required when verifying meters).

Note: The order of assessing distortion is up to the evaluator and the assessment can be done at any convenient time when the applicable burdens are installed on the console for other calibration console assessments.

7.5.3 Procedures for the assessment of distortion using recti-thermal demand meters

  1. Install recti-thermal demand meters as they would be installed under normal testing, in all but one MUT position. Self-contained meters that have a high voltage and current rating should be used for all high voltage and current tests. Appropriately rated transformer-type meters (e.g. 120 volt, 10 amps) must be used for all low voltage and current test points.
  2. Install the test socket in the empty MUT position.
  3. Set the console for the type of meters that are installed on the console.
  4. Ensure that any regulators or line conditioners that are always in the circuit during normal meter testing remain in the circuit for all the following distortion tests.
  5. If any regulators or line conditioners may be switched out of the circuit, do so.
  6. Connect the current terminals of the distortion analyzer in series with one of the current elements at the test socket. Ensure that the other two current circuits are shorted at the socket.
  7. Connect the voltage terminals of the analyzer in parallel with the test voltage at the socket.
  8. Set the load to 120 volts, 2.5 amps, 0.5 power factor.
  9. Energize the console to the specified test point and record the measured value of current and voltage distortion in the first table of the Distortion section of the worksheets. De-energize the console.
  10. If any regulators or line conditioners were switched out of the circuit in step (5), turn them on and repeat all of the distortion measurements at the test loads previously used by following steps (6) to (9).
  11. Repeat all the steps above for the load setting that includes the maximum demand verification test current and voltage ensuring the installed meters are appropriately rated.

7.5.4 Procedure for the assessment of distortion for 1:1 CTs and multiple PTs

  1. Install appropriate burdens as determined in 7.3.4.5 and 7.3.4.6 above in all but one MUT position. Install the meters as they would be installed under normal testing using 1:1 isolation transformers and multiple potential transformers.
  2. Any regulators or line conditioners that are always in the circuit during normal meter testing shall remain in the circuit for all the following distortion tests.
  3. If any regulators or line conditioners may be switched out of the circuit, do so.
  4. Connect the current terminals of the analyzer in series with the current elements at the test socket. Ensure that the other two current circuits are shorted at the socket.
  5. Connect the voltage terminals of the analyzer in parallel with the test voltage at the socket.
  6. Set the load to 120 volts and 2.5 amps.
  7. Energize the console to the specified test point and record the measured value of current and voltage distortion in the second table of the Distortion section of the worksheets. De-energize the console.
  8. Set the load to the maximum test current used for verifying meters that require the use of 1:1 transformers and /or multiple transformers and the maximum test voltage used for verifying meters that require the use of multiple transformers (typically 240 volts).
  9. Repeat step (7).
  10. If any regulators or line conditioners were switched out of the circuit in step (3), turn them on and repeat all of the distortion measurements at the test loads previously used by following steps (6) to (9).

7.5.5 Procedure for the assessment of distortion for other meters
(no 1:1 CT or multiple PT in circuit)

  1. Install meters, simulating the burden requirements as specified in section 7.3.2.6 of EL-ENG-12-01, in all but one MUT position. Install the meters as they would be under normal testing.
  2. Any regulators or line conditioners that are always in the circuit during normal meter testing shall remain in the circuit for all the following distortion tests.
  3. If any regulators or line conditioners may be switched out of the circuit, do so.
  4. Connect the current terminals of the analyzer in series with the current elements at the test socket. Ensure that the other two current circuits are shorted at the socket.
  5. Connect the voltage terminals of the analyzer in parallel with the test voltage at the socket.
  6. Set the load to 120 volts and 2.5 amps.
  7. Energize the console to the specified test point and record the measured value of current and voltage distortion in the second table of the Distortion section of the worksheets. De-energize the console.
  8. Set the load to the maximum test current and maximum test voltage used for verifying meters that require the use of the burden determined pursuant to section 7.3.2.6 of EL-ENG-12-01.
  9. Repeat step (7).

7.5.6 Formula

The distortion analyzer must calculate distortion according to the following formula:

7.6 Regulation (EL-ENG-12-01, s. 7.6)

7.6.1 Purpose

The purpose of section 7.6 of EL-ENG-12-01 is to ensure that consoles are capable of holding test loads stable when verifying demand meters.

7.6.2 Guidelines

  1. This procedure involves setting a load and monitoring energy recorded at consecutive one-minute intervals for up to sixty minutes. The recorded one-minute energy values are compared to a target value to ensure compliance with the tolerance of section 7.6.1.1.1 of EL-ENG-12-01.
  2. The recording and monitoring of one-minute energy values is typically accomplished by using a proprietary NRG test board analyzer. Some console owners have developed similar devices for use with this test that must have the following basic characteristics:
    1. The devices shall capture energy pulses at intervals of one minute ±0.05%.
    2. The one-minute energy registrations need to be read in measurement units or pulses to a resolution of 0.01% of the expected target value.
  3. Any device used for this assessment will require acceptance by the MC Regional Specialist before it can be used.

7.6.3 Procedure

  1. Install the burdens determined pursuant to procedure 7.3.4.6 above in each MUT position except the MUT position including the Radian standard. Set the calibration console load to the following test load: 2.5A, 120V, 0.5 power factor.
  2. The calibration console may be allowed to warm-up for a period of up to one hour, if required. The worksheets must indicate if the console requires warm-up and the period applicable. The warm-up period for demand tests must also be identified on the console certificate.
  3. Using the device identified in 7.6.2(2), monitor the calibration console energy units at one-minute intervals for the required period.
  4. The load being regulated is to be monitored for a period of two times the demand test period required for the verification of meters or 60 minutes, whichever is shorter. For example, if the demand test period for the verification of meters approved for test mode verification is 5 minutes, and it is the longest demand test period that the console will be used for, the regulation assessment required is 10 minutes.
  5. The load used for the assessment of the regulation test shall be determined by averaging 5 one-minute energy readings and calculating the load used as the target to which all one-minute registrations shall be compared.
  6. After the required test time is completed, stop the test.
  7. Conduct the regulation test for each applicable demand measurement unit the console will be used for verifying.
  8. Install self-contained burdens applicable to the rating of the highest demand verification test current at the corresponding voltage.
  9. Repeat the regulation test with the load set to the largest test load used to verify exponential or block interval demand meters that cannot be verified pursuant to section 6.4.9 of EL-ENG-12-01.
  10. Conduct the test for each demand measurement unit the console will be used for verifying.

7.7 Current switching effects (EL-ENG-12-01, s. 7.7)

7.7.1 Purpose

The purpose of EL-ENG-12-01 section 7.7 is to determine if semi-automatic and automatic console errors change when automatically switching currents from high to low loads.

7.7.2 Guidelines

Consoles that have transformers installed between the reference meter and the MUT position are most prone to exhibiting error changes from this test. The errors are usually introduced by the phenomenon known as remanence. In order to detect the effects of remanence, tests are carried out by connecting a standard in a MUT position, setting a load current, and switching the current to 10% of its original setting. The load is then returned to the original setting and the apparent errors before and after the switch to light load and back up to the full load are compared.

7.7.3 Procedure for the assessment of consoles equipped with 1:1 CTs

  1. Install the burdens determined pursuant to the procedure 7.3.4.5 above in all but one MUT position.
  2. Install the test socket in the remaining test position with the applicable burden.
  3. Connect the standard as described in section 7.3 above.
  4. Make connections to put 1:1 isolation transformers in circuit.
  5. Set the load determined pursuant to 7.3.4.5 above.
  6. Calibrate the console using its normal operating mode.
  7. Record the error of the standard on the calibration worksheet.
  8. Switch the current to 10 percent, and then back to its original value.
  9. Re-calibrate the console and record the results on the calibration worksheet.
  10. Repeat the process four times and record each result on the calibration worksheets.

Note: Follow normal operating procedures for the console when conducting these tests. If normal operation requires that the load be set to zero before switching to a new load, do so.

7.7.4 Procedure for the assessment of consoles equipped with intervening transformers other than 1:1 CTs

  1. Install polyphase meters or burdens determined pursuant to the procedure 7.3.4.6 or 7.3.4.7 above in all but one MUT position.
  2. Install the test socket in the remaining test position with the applicable burden.
  3. Connect the standard as described in section 7.3 above.
  4. Set the load determined pursuant to 7.3.4.6 or 7.3.4.7 above.
  5. Calibrate the console using its normal operating mode.
  6. Record the error of the standard on the calibration worksheet.
  7. Switch the current to 10 percent, and then back to its original value.
  8. Re-calibrate the console and record the results on the calibration worksheet.
  9. Repeat the process four times and record each result on the calibration worksheets.

Note: Follow normal operating procedures for the console when conducting these tests. If normal operation requires that the load be set to zero before switching to a new load, do so.

7.7.5 Remarks

The tolerance for the errors determined by this procedure is specified in section 7.7.1 of EL-ENG-12-01.

(Spread of error) = (Emax) − (Emin)

Where:

Example

Five errors recorded as: 0.08%, 0.08%, −0.05%, 0.09% and 0.07%

Spread = (0.09%) − (−0.05%)

Spread = 0.14%

7.8 Console calibration (EL-ENG-12-01, 7.8)

7.8.1 Purpose

The purpose of section 7.8 of EL-ENG-12-01 is to determine certified errors of calibration consoles.

7.8.2 Guidelines

  1. The extent to which a console is calibrated depends on the way it is used. Section 7.8 of EL-ENG-12-01 defines various criteria for use. The calibration procedures associated with various criteria are described below.
  2. A calibration console equipped with 1:1 isolation current transformers used with multiple potential transformers is required to be assessed at each position equipped with a 1:1 transformer with the multiple potential transformer at each test point used for testing meters for which 1:1 transformers are required.
  3. A calibration console equipped with multiple potential transformers that are not used with 1:1 current transformers is required to be tested at each position equipped with a multiple potential transformer at each test point used for testing meters for which multiple transformers are required (e.g. two-element meter with only one potential test link).
  4. A calibration console that is used without 1:1 current transformers or multiple potential transformers but has other current and/or potential transformers connected between the reference meters and the MUT positions is to be calibrated at any one MUT position for the combinations of voltage and current tap, and selector switch settings. This includes transformer-type and self-contained polyphase meters. Calibration is performed at the maximum and minimum test loads for each combination of voltage and current tap, and selector switch combination used to verify meters. The calibration at these test loads is conducted at all power factors used to verify meters.
  5. A calibration console similar to (4) above, with the exception that the reference meters are connected in the same circuit as the MUT positions without any intervening current or potential transformers or isolation transformers between the reference meters and the MUT positions, is required to be calibrated at any one MUT position at the minimum, median and maximum test load of the range of loads at each test voltage, at unity power factor or all other power factors used to verify meters included in the list provided pursuant to section 5.2.6 of EL-ENG-12-01.

    Maximum load is equal to meter test voltage times meter test current that creates the maximum load.

    Median load is equal tometer test voltage times meter test current that creates the middle load of range of meter test loads.

    Minimum load is equal tometer test voltage timesmeter test current that creates the minimum meter test load.

  6. Calibration consoles that apply voltages and or currents to individual circuits (elements) of a meter from independent sources (e.g. consoles using amplifiers as opposed to loading transformers) shall have each source or combination of sources calibrated for each element or combination of elements for each test point to be used to verify meters included in the applicable list provided pursuant to section 5.2.6 of EL-ENG-12-01. Each MUT will be calibrated as stated in (2) to (5) above.
  7. Consider the testing needs of 7.9 before completing the 7.8 calibrations, since the test points may need to be repeated.

7.8.3 Procedure for 1:1 CT and/or multiple PT calibration

  1. Use the procedures described in section 7.3 of this document to calibrate the console.
  2. Install the appropriate burden determined from section 7.3.4.5 of the procedure above in each position.
  3. Install the burden as determined pursuant to section 7.3.4.5 of the procedure above in parallel with the voltage circuit. The exception to this is when the burden effects determined in section 7.3.4.5 of this procedure are less than 0.05%.
  4. Calibrate each MUT position equipped with 1:1 isolation transformers and/or multiple transformers at every test point used with 1:1 transformers in circuit.
  5. Calibrate each MUT position equipped with multiple transformers at every test point used with multiple potential transformers without 1:1 transformers in circuit.
  6. Repeat steps (1) to (5) as applicable for all electrical quantities used for verifying meters.
  7. Refer to section 7.9 of the procedure for repeated runs and additional data for uncertainty calculations.

7.8.4 Procedure for the calibration of consoles without isolation transformers with other intervening transformers connected between the reference meters and the MUT positions

  1. Determine if the console has intervening transformers, other than isolation transformers, between the reference meters and the MUT positions.
  2. Use the procedures described in section 7.3 above to calibrate the console at one MUT position only.
  3. For the calibrations below, install the burden determined pursuant to section 7.3.4.6 or 7.3.4.7 above in each test position.
  4. Install the burden as determined pursuant to section 7.3.4.6 or 7.3.4.7 above in parallel with the voltage circuit. The exception to this is when the burden effects determined in section 7.3.4.6 or 7.3.4.7 of this procedure are less than 0.05%.
  5. Determine all combinations of voltage and current tap, and selector switch settings used for verifying meters. Calibrate the console at the maximum and minimum test loads for each combination of voltage and current tap, and selector switch combination used to verify meters.
  6. Calibrate the console at these test loads at all power factors and electrical quantities used to verify meters.
  7. Refer to section 7.9 of the procedure for repeated runs and additional data for uncertainty calculations.

7.8.5 Procedure for the calibration of consoles with the reference meters in the same circuit as the MUT positions

  1. Determine if the console has reference meters that are in the same circuit as the MUT positions.
  2. Use the procedures described in section 7.3 of this document to calibrate the console at one MUT position only.
  3. For the calibrations below, install the burden determined pursuant to section 7.3.4.6 or 7.3.4.7 above in each test position.
  4. Install the burden as determined pursuant to section 7.3.4.6 or 7.3.4.7 above in parallel with the voltage circuit. The exception to this is when the burden effects determined in section 7.3.4.6 or 7.3.4.7 of this procedure are less than 0.05%.
  5. Calibrate the console at any one MUT position at the minimum, median and maximum test loads of the range of test loads at each test voltage at unity power factor, as well as all the other power factors to be used to verify meters (see 7.8.2.5 above for an explanation of maximum, minimum and median loads).
  6. Repeat steps (1) to (5) as applicable for all electrical quantities used for verifying meters.
  7. Refer to section 7.9 below for repeated runs and additional data for uncertainty calculations.

7.8.6 Procedure for the calibration of consoles that apply voltage and/or current to individual circuits (elements) of a meter from independent sources

  1. Determine if the console applies voltage and or current to the individual circuits representing the metering elements of a meter from independent sources.
  2. Use the procedures described in section 7.3 to calibrate the console.
  3. Calibrate the console for each source or combinations of sources for each element or combination of elements.
  4. Calibrate for each test point to be used to verify meters at MUT positions as stated in 7.8.3 to 7.8.5 above, as applicable.
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