POWER METERING TERMINOLOGIES ABBREVIATIONS BASIC AND TUTORIALS

Kh - Kh is the meter disk watt-hour constant representing the number of watt-hours per revolution of the disk.

Rr - Rr is the register ratio. This is the relationship between the first take off gear on the meter’s register and the far right hand dial on the front of the register.

Rs - Rs represents the first shaft reduction. This is the relationship between the worm wheel on the disk shaft and the first take off gear on the meter’s register.

Rg - Rg is the relationship between the worm wheel on the disk shaft and the far right hand dial on the meter. It may be calculated by multiplying Rs times Rr.

Kr - The term "Kr" is used to represent the dial multiplier for the meter.

CT - Current Transformer.

VT - Voltage Transformer.

TF - Transformer Factor may be determined from the turns ratio of the CT’s and VT’s. The transformer factor is VT ratio times CT ratio or simply CT ratio if VT’s are not being used.

RF - Rating Factor is the overload factor for current transformers. Exceeding this rating may cause metering inaccuracies as well as risking damage to the CT.

PKh - Primary Kh represents the true disk watt-hour constant for instrument rated meters. PKh may be determined by multiplying Kh times the instrument transformer ratios (TF).

CL - Class rating is the maximum amperage rating of the current coils in the meter. This value is clearly stamped on the nameplate of all modern meters.

TA - Test amp rating. Meters are given a full load test at rated voltage with this value of current. In addition, they are tested with 10% of the

TA rating for a light load accuracy test.

W - Number of circuit wires the meter’s stator is designed to meter. The neutral counts as one of the wires. Furthermore, under certain conditions, meters are applied to circuits with more or less circuit wires than stated on the meter’s nameplate.

FM - FM is used as an abbreviation for form as in FM 9S meter.

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