Chapter PSC 113

PSC 113.0811(1)(c) (c) If the meters are designed for use on alternating current circuits, they shall be accurate to within plus or minus 1% at 2 load tests: one equal to between 8% and 12% of full reference test current at unity power factor and the other between 90% and 110% of full reference test current at unity power factor; and for polyphase meters, shall be accurate to within plus or minus 2% at between 75% and 100% full reference test current and approximately 50% lagging power factor. For self-contained meters the reference test current shall be the ampere or test ampere rating of the meter, whichever is shown on the nameplate. For meters used with current transformers the reference test current shall be the test-ampere rating of the meter or the secondary rating of the current transformers.

PSC 113.0811 Note Note: See s. PSC 113.0926 (2) for accuracy requirements for meters operating in the reverse-registration mode.

PSC 113.0811(2) (2) Polyphase meters shall have their stators in balance within 2% at 100% load at unity and at approximately 50% lagging power factor.

PSC 113.0811(3) (3) Meters used with instrument transformers shall be adjusted, if necessary, so that the overall accuracy of the metering installation will meet the requirements of this rule.

PSC 113.0811 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00; CR 02-027: r. (4), Register December 2002 No. 564, eff. 1-1-03.

PSC 113.0812 PSC 113.0812 Accuracy of demand meters. In this section, “meter” or “meters” may refer to metering system(s).

PSC 113.0812(1) (1) A demand meter, demand register, or demand attachment used to measure customer’s service shall:

PSC 113.0812(1)(a) (a) Be in good mechanical and electrical condition.

PSC 113.0812(1)(b) (b) Have proper constants, indicating scale, contact device and resetting device.

PSC 113.0812(1)(c) (c) Not register at no load.

PSC 113.0812(1)(d) (d) Be accurate to the following degrees:

PSC 113.0812(1)(d)1. 1. Curve drawing meters which record quantity time curves and integrated-demand meters shall be accurate to within plus or minus 2.0% of full scale throughout their working range. Timing elements measuring specific demand intervals shall be accurate to within plus or minus 2.0% and the timing elements which serve to provide a record of the time of day when the demand occurs shall be accurate to within plus or minus 4 minutes in 24 hours.

PSC 113.0812(1)(d)2. 2. Lagged-demand meters shall be accurate to within plus or minus 4% of full scale at final indication.

PSC 113.0812(2) (2) The overall accuracy of demand metering installations utilizing pulse-initiator and pulse-recorder equipment shall be acceptable when the monthly kilowatt-hours calculated from the pulse count do not differ from the corresponding kilowatt-hour meter registrations by more than the kilowatt-hour constant of the meter, or 2%, whichever is greater. The timing element error shall not be more than plus or minus 4 minutes per day.

PSC 113.0812(3) (3) When a timing element also serves to keep a record of the time of day at which the demand occurs, it shall be corrected if it is found to be in error by more than plus or minus 4 minutes per day.

PSC 113.0812 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0813 PSC 113.0813 Requirements for instrument transformers.

PSC 113.0813(1) (1) Instrument transformers used in conjunction with metering equipment to measure customers’ service shall:

PSC 113.0813(1)(a) (a) Be in proper mechanical condition and have electrical insulation satisfactory for the service used.

PSC 113.0813(1)(b) (b) Be 0.3% accuracy-class units and otherwise have characteristics such that the combined inaccuracies of all transformers supplying one or more meters in a given installation will not exceed the total accuracies for the following conditions:

PSC 113.0813(1)(b)1. 1. Power factor equals 1.0 and 10% load, accuracy equals 0.6%.

PSC 113.0813(1)(b)2. 2. Power factor equals 1.0 and 100% load, accuracy equals 0.3%.

PSC 113.0813(1)(b)3. 3. Power factor equals 0.5 and 100% load, accuracy equals 1.0%.

PSC 113.0813(2) (2) 

PSC 113.0813(2)(a) (a) Meters used in conjunction with instrument transformers shall be adjusted so that the overall accuracies will come within the limits specified ss. PSC 113.0811 and 113.0812.

PSC 113.0813(2)(b) (b) Instrument transformers shall be tested with the meter with which they are associated by making an overall test, or may be checked separately. If the transformers are tested separately, the meters shall also be checked to see that the overall accuracy of the installation is within the prescribed accuracy requirements.

PSC 113.0813(2)(c) (c) The results of tests of instrument transformers shall be kept on record and available for use when transformers are installed. For other than 0.3% accuracy class instrument transformers, the results of the most recent test for each instrument transformer shall be entered on or attached to the test card form for each test of the associated meter prior to the test of that meter.

PSC 113.0813(3) (3) Phase shifting transformers shall have secondary voltages under balanced line-voltage conditions within 1% plus or minus of the voltage impressed on the primary.

PSC 113.0813 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0814 PSC 113.0814 Portable indicating instruments. All portable indicating electrical instruments used for determining quality of service to customers or for billing purposes, such as voltmeters, ammeters and watt meters, shall be checked against suitable secondary reference standards at least once in each 6 months. If the portable indicating instrument is found appreciably in error at zero or in error by more than 1% of indication at commonly used scale deflections, it shall be adjusted. A history and calibration record shall be kept for each such instrument.

PSC 113.0814 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0815 PSC 113.0815 Type of instruments. All electric service of the same type rendered under the same rate schedule shall be metered with instruments having like characteristics, except that the commission may approve the use of instruments of different types if their use does not result in unreasonable discrimination. Either all of the reactive meters which may run backwards or none of the reactive meters used for measuring reactive power under one schedule shall be ratcheted.

PSC 113.0815 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0816 PSC 113.0816 Servicing utilization control equipment.

PSC 113.0816(1) (1) Utilities shall service and maintain any equipment they use on customers’ premises so as to provide service in accordance with the rate provisions.

PSC 113.0816(2) (2) Systems and devices used by the utility to control customer metering and loads shall be tested or checked on installation and periodically thereafter, if necessary, to verify proper operation.

PSC 113.0816 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0817 PSC 113.0817 Metering at point of interchange and for customers’ operating generating equipment.

PSC 113.0817(1) (1) Metering facilities located at any point where energy may flow in either direction and where the quantities measured are used for billing purposes shall consist of meters equipped with ratchets or other devices to prevent reverse registration and be so connected as to separately meter energy flow in each direction. Reverse meter registration is permitted for installations with customer-owned generators served under a net billing energy rate through one meter in accordance with s. PSC 113.0926.

PSC 113.0817(2) (2) Reactive metering shall not be employed for determining average power factor where energy may flow in either direction or where the customer may generate an appreciable amount of his or her requirements at any time unless suitable directional relays and ratchets are installed to obtain correct registration under all conditions of operation and unless the general plan of installation is approved by the commission.

PSC 113.0817 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0818 PSC 113.0818 Determination of average meter error. Whenever a metering installation is found upon any test to be in error by more than 2% at any test load, the average error shall be determined in one of the following ways:

PSC 113.0818(1) (1) If the metering installation is used to measure a load which has practically constant characteristics, such as a street-lighting load, the meter shall be tested under similar conditions of load and the accuracy of the meter “as found” shall be considered as the average accuracy.

PSC 113.0818(2) (2) If a single-phase metering installation is used on a varying load, the average error shall be the weighted algebraic average of the error at light load and the error at heavy load, the latter being given a weighting of 4 times the former.

PSC 113.0818(3) (3) If a polyphase metering installation is used on a varying load, the average error shall be the weighted algebraic average of its error at light load given a weighting of 1, its error at heavy load and 100% power factor given a weighting of 4 and at heavy load and 50% lagging power factor given a weighting of 2.

PSC 113.0818(4) (4) If a load, other than the light, heavy and low power-factor load specified for routine testing, is more representative of the customary use of the metering equipment, its error at that load should also be determined. In this case the average error is to be computed by giving the error at such load and power factor a weighting of 3 and each of the errors at the other loads (light, heavy and 50% lagging power factor) a weighting of 1. Each error shall be assigned its proper sign.

PSC 113.0818 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

subch. IX of ch. PSC 113 Subchapter IX — Electric Meter Testing Programs and Record Requirements

PSC 113.0901 PSC 113.0901 Testing of metering installations-general requirements.

PSC 113.0901(1) (1) The test of any unit of metering equipment shall consist of a comparison of its accuracy with a standard of known accuracy by a qualified person. Units not properly connected or not meeting the accuracy or other requirements of ss. PSC 113.0811, 113.0812 and 113.0813 at the time of test shall be reconnected and/or rebuilt to meet such requirements and adjusted to within the required accuracy and as close to 100% accurate as practicable or their use discontinued.

PSC 113.0901(2) (2) Each unit of metering equipment shall be inspected for mechanical and electrical faults whenever the accuracy of the device is checked.

PSC 113.0901(3) (3) Each meter tested shall have the register and the internal connections checked before the meter is first placed in service and whenever the meter is repaired.

PSC 113.0901(4) (4) Each meter shall have the connections to the customer’s circuits, the disc rotation and any multiplier checked when the meter is installed or removed or an instrument transformer is changed.

PSC 113.0901(5) (5) Polyphase meters shall be tested for accuracy at 50% power factor before first being used for measuring customer’s service either by a test of each meter or by a sample test plan approved under s. PSC 113.0911 (1) (a).

PSC 113.0901(6) (6) The connections, phase sequence and multiplier of polyphase transformer-rated metering installations shall be checked for error by qualified personnel within 60 days after the meter is installed.

PSC 113.0901(7) (7) Special control devices, switches, etc., for time-of-use service shall be checked for proper operation whenever the associated meter is tested.

PSC 113.0901 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0902 PSC 113.0902 Testing equipment.

PSC 113.0902(1) (1) Each utility shall maintain sufficient laboratories, meter testing shops, secondary standards, instruments and facilities to determine the accuracy of all types of meters and measuring devices used by the utility. A utility may, however, with the approval of the commission, have all or part of the required tests made or its portable testing equipment checked by the original equipment manufacturers, another utility, or testing agency having adequate and sufficient testing equipment to comply with these rules.

PSC 113.0902(2) (2) Each utility shall have the following minimum testing equipment available:

PSC 113.0902(2)(a) (a) One or more portable standard watthour meters of capacity and voltage range adequate to test all watthour meters used by the utility.

PSC 113.0902(2)(b) (b) Portable indicating instruments of such various types as are required to determine the accuracy of all instruments used by the utility.

PSC 113.0902(2)(c) (c) One or more secondary standards to check each of the various types of portable standard watthour meters used for testing watthour meters. Each secondary standard shall consist of either an approved portable standard watthour meter kept permanently at one point and not used for field work, or not less than three approved watthour meters connected with current coils in series and voltage coils in parallel and kept running by connecting a 10-watt load. These meters must be well compensated for both classes of temperature errors, practically free from errors due to ordinary voltage variations and free from erratic registration due to any cause.

PSC 113.0902(2)(d) (d) Suitable standards which are not used for field work to check portable instruments used in testing.

PSC 113.0902(3) (3) Any utility having more than 10,000 customers, or any other utility upon approval of the commission, may provide and use primary standards consisting of precision instruments, timing devices, potentiometers, standard cells, etc.

PSC 113.0902 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0903 PSC 113.0903 Accuracy and calibration of test standards.

PSC 113.0903(1) (1) 

PSC 113.0903(1)(a) (a) Utilities maintaining primary standards such as precision wattmeters, volt boxes, resistances, standard cells and timing devices shall have such standards certified at the time of purchase as to accuracy by a recognized laboratory other than that of the manufacturer of the standard.

PSC 113.0903(1)(b) (b) Utilities having standard cells shall intercompare them regularly and shall have at least one of them checked by a standardizing laboratory at intervals of not more than 2 years. Reference standards of resistance, potentiometers and volt boxes shall be checked at intervals of not more than 3 years.

PSC 113.0903(2) (2) 

PSC 113.0903(2)(a) (a) Secondary watthour-meter standards shall not be in error by more than plus or minus 0.3% at loads and voltages at which they are to be used and shall not be used to check or calibrate working standards unless the secondary standard has been checked and adjusted, if necessary, to such accuracy within the preceding 12 months. Each secondary standard watthour meter shall have a calibration curve available and a history card.

PSC 113.0903(2)(b) (b) Any 2 or more of at least 3 watthour meters may be used as a secondary standard to check portable rotating standards provided there is no discrepancy in accuracy between any 2 of the watthour meters used of more than 0.2% at standard test loads. Calibration and history records shall be maintained for each of the meters used as secondary standards.

PSC 113.0903(3) (3) Secondary standards indicating instruments shall not be in error by more than plus or minus 0.5% of indication at commonly used scale deflection and shall not be used to check or calibrate portable indicating instruments unless the secondary standard has been checked and adjusted, if necessary, within the preceding 12 months. A calibration record shall be maintained for each standard.

PSC 113.0903(4) (4) All working portable standard watthour meters shall be calibrated annually (see ss. PSC 113.0706 and 113.0904) and shall be adjusted, if necessary, so that their accuracy will be within 99.7% and 100.3% at 100% power factor and for polyphase applications, within 99.5% and 100.5% at 50% lagging power factor at all voltages and loads at which the standard may be used. A history and calibration record shall be kept for each working portable standard watthour meter.

PSC 113.0903(5) (5) The meter accuracies herein required as to all primary, secondary and portable standards and service measuring equipment shall be referred to 100%.

PSC 113.0903 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0904 PSC 113.0904 Watthour calibration. Each utility which normally checks its own working portable standard watthour meters or instruments against primary or secondary standards shall calibrate these standards or instruments before they are submitted to a commission-approved test facility annually and attach to them a record of such calibration.

PSC 113.0904 Note Note: Previously s. PSC 113.46 (2), with changes.

PSC 113.0904 History History: Cr. Register, July, 2000, No. 535, eff. 8-1-00.

PSC 113.0905 PSC 113.0905 Methods of testing watthour meters.

PSC 113.0905(1) (1) In all tests of watthour meters where comparison of revolutions is made, at least 2 revolutions of the meter under test shall be taken at light load and at least 9 revolutions at heavy load. At least 2 checks shall be made at each load. The accuracy of the meter under test at each load shall be the average accuracy determined from 2 checks taken at the same load which must agree within 0.2 of 1%. However, if an electro-optical testing device is used, the test procedure may be modified, provided equal accuracy of the method is maintained.

PSC 113.0905(2) (2) If the watthour meter has a contact device which operates a demand mechanism, the disk revolutions when testing should be multiples of the number of revolutions per contact in order to take account of the varying friction which may be present during the movement of the contact cam from one contact to the next.

PSC 113.0905(3) (3) Polyphase meters shall be tested by one of the following 4 methods:

PSC 113.0905(3)(a) (a) Single-phase test with the potential circuits connected in parallel and all current circuits connected in series. Three-stator, 4-wire delta meters must have correct values of current and potential applied to the differently rated circuits. The normal test loads apply. (See s. PSC 113.0811 (1) (c).)

PSC 113.0905(3)(b) (b) Individual stator test with the potential circuits connected in parallel and each current circuit tested separately. (For 2-stator, 4-wire delta meters, the current circuits of the 3-wire stator should be connected in series and treated as a single circuit. Three-stator, 4-wire delta meters must have correct values of potential applied to the differently rated circuits.) The light load test current shall be one-tenth N times the reference test current and the heavy load test current shall be between one-half and one N times the reference test current but not more than twice the test ampere rating of the meter. (N equals the number of stators in the meter except for 2-stator, 3-phase, 4-wire wye meters. For the latter, N shall be 4 for the current circuits which are not common to both stators and N shall be 2 for the current circuit common to both stators.)

PSC 113.0905(3)(c) (c) Individual stator test with the potential circuits connected to the polyphase circuit in the same manner as in service. (For 2-stator, 4-wire delta meters the current circuits of the 3-wire stator shall be connected in series and treated as a single circuit.) The light load test current shall be one-tenth N times the reference test current and the heavy load test current shall be between one-half and one N times the reference test current but not more than twice the test ampere rating of the meter. (N equals the number of stators in the meter except for 2-stator, 3-phase, 4-wire meters. For the latter N shall be 3 for each current circuit.)

PSC 113.0905(3)(d) (d) Polyphase test with the meter connected to a polyphase circuit in the same manner as in service, with balanced polyphase currents on the current circuits. This requires the use of a polyphase standard watt-hour meter or as many single-phase standards as there are current circuits under test.

PSC 113.0905(4) (4) Instrument transformers shall be tested with a burden equivalent to that with which they are to be used or with burdens from which curves showing the accuracy of the transformer can be derived. Any approved method may be used for testing instrument transformers. Also see s. PSC 113.0916.