Okla. Admin. Code § 165:35-15-12

Current through Vol. 42, No. 7, December 16, 2024

Section 165:35-15-12 - Accuracy requirements for service watt-hour meters

(a)General. No meter shall be placed in service, or allowed to remain in service, which has an incorrect register multiplier, watt-hour constant, gear ratio, or dial train; or which is mechanically or electrically defective, incorrectly connected, installed, or applied; or which registers outside the limits specified in (c) of this Section. All tolerances in this Chapter are to be interpreted as maximum permissible variations from conditions of zero error. No meter or associated device shall be adjusted to be in error, even within the tolerances permitted by this Chapter.

(b)Test loads. For self-contained meters, the heavy load test current shall be approximately one hundred percent (100%) of the meter test amperes (TA), and the light load test current shall be approximately ten percent (10%) of the meter test amperes (TA). For meters used with current transformers, the current at heavy load shall be approximately one hundred percent (100%) of either the meter test amperes (TA) or the secondary rating of the current transformer, and at light load approximately ten percent (10%) of that rating.

(c)Accuracy limits.

(1)Acceptable performance. The performance of a watt-hour meter is considered to be acceptable when the average percentage registration is not more than one hundred and two percent (102%), nor less than ninety-eight percent (98%), calculated in accordance with one of the methods described in (d) of this Section.

(2)Adjustment limits. When the test of a watt-hour meter indicates that the error in registration exceeds one percent (1%) at either light load or heavy load at unity power factor, or exceeds two percent (2%) at heavy load at approximately 0.5 power factor lag, the percentage registration of the meter shall be adjusted to within these limits of error, as closely as practicable to the condition of zero error. Where instrument transformers are used in conjunction with the meter, these limits apply to the meter equipment as a whole. All meters which are tested shall be left without creep.

(3)Creeping. No watt-hour meter which creeps shall be placed in service or allowed to remain in service. A meter creeps if, with load wires removed and with test voltage applied to the voltage circuits, the rotor moves continuously. For the practical recognition of creep in a meter in service, it is considered to creep when, with all load wires disconnected, the rotor makes one (1) revolution in ten (10) minutes or less.

(d)Percentage registration.

(1)Method 1. Weighted average percentage registration is the wighted average of the percentage registration at light load (LL) and at heavy load (HL) registration a weight of four (4). By this method: Weighted Average Percentage Registration = (LL + 4HL) / 5.

(2)Method 2. Average percentage registration is the average of the percentage registration at light load (LL) and at heavy load (HL). By this method: Average Percentage Registration = (LL + HL) / 2.

(e)Compliance with ANSI. The consumer who utilizes a consumer submeter or consumer submeters shall not place in service such meters unless said consumer submeters comply with the current version of ANSIC12 Standard, or equivalent ANSI standard as later amended.

Okla. Admin. Code § 165:35-15-12

Amended at 10 Ok Reg 2633, eff 6-25-93; Amended at 16 Ok Reg 2237, eff 7-1-99