Section PSC 113.0903 - Accuracy and calibration of test standards(1)(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.(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.(2)(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.(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.(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.(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.(5) The meter accuracies herein required as to all primary, secondary and portable standards and service measuring equipment shall be referred to 100%.Wis. Admin. Code Public Service Commission § PSC 113.0903
CR Register, July, 2000, No. 535, eff. 8-1-00.