Wisconsin Administrative Code › Public Service Commission › Chapter PSC 113 - Service Rules For Electrical Utilities › Subchapter IX - Electric Meter Testing Programs and Record Requirements › Section PSC 113.0905 - Methods of testing watthour meters

Current through June 24, 2024
(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.
(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.
(3) Polyphase meters shall be tested by one
				of the following 4 methods:
(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).)
(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.)
(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.)
(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.