Metering Formula

Metering Formula
1. Meter Multiplier
Meter Multiplier - the multiplier applied to the register reading to obtain kilowatt-hours. M = Kh X Rr X Rs X CTR X VTR
10,000
Where ;
Kh = watt-hour constant of the meter in watt-hour per revolution
Rr = register ratio = the number of revolutions of the register worm wheel for a revolution of the first dial pointer (right hand).
Rs = gear ratio = the number of revolution of the disk for one revolution of the first point
CTR = current transformer ratio
VTR = voltage transformer ratio
Example #1:
A G.E., three phase, three wire, 120 volts, type VM-63-A, Form 5A, Class 20,
KWh meter indicates Kh of 2.4 at its nameplate and register ratio of 166-2/3 was installed at 13.2 KV wye grounded system having a current transformer of
25:5 ratio. Determine the following;
a). The internal multiplier
b). The billing multiplier
Solution:
a). Internal Multiplier = Kh X Rr X Rs
10,000
For G.E.;
Rs =50 for Type V-60, DS-50 and DS-60 Family
Rs = 100 for Other family
For Sangamo;
Rs = 100 for J3 meters
Rs = 50 for J4 and Polyphase meters
For Westinghouse;
Rs = 100 for all types of meter
Internal Multiplier = 2.4 X 166-2/3 X 50
10,000
Internal Multiplier = 2
b). Billing Multiplier = Kh X Rr X Rs X CTR X VTR
10,000
Billing Multiplier = 2.4 X 166-2/3 X 50 X 25 X 70
10,000
5
1
Billing Multiplier = 700

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Example #2:
A single phase, 2-wire, bottom connected Harbin meter, type DD101x-6E,
15(100)A, having a 210 rev per KWh and 28 register ratio, determine the multiplier. Solution :
Kh = 1000 watts/Kilowatt
210 rev/KWh
Kh = 4.761904761905 Wh/rev.
Or Kh = 4.762 Wh/rev.
Based on Manufacturer certification issued to NEA gear ratio is 75
Multiplier = 4.762 Wh/rev. X 28 X 75
10,000
Multiplier = 1
2. Meter Watthour Constant (K h)
Meter Watthour Constant (K h) - the number of watthour represented by one revolution of the disk.
Kh = Voltage X Current X Number of Elements
RPM X 60
Where;
Voltage -