Metering Formula Essay
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
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
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 …show more content…
CR = Kh(MUT) X Rev. (MUT)
Kh(std) X No. of Element X V(MUT) where; Kh(MUT), Kh(std) - meter constant of Meter Under Test (MUT) and standard, respectively
Rev.(MUT) - number of rev. of Meter Under Test (MUT)
No. of Element - number of element or stator in used
V(std), V(MUT) - Voltage induced to standard and Meter Under Test
c. Average Accuracy = 70% Full Load + 30% Light Load or = 75% Full Load + 25% Light Load
d. Percent Error = Computed Rev. - Actual Rev. X 100%
Actual Rev. or Percent Error = Computed Rev. - 1 X 100%
Percent Error = (%A - 1) X 100% where :
%A - Percent Accuracy
Given : a) Meter - Three phase G.E. meter self-contained, class 200, Form 12S, Kh
28.8 Rr 166-2/3 240 volts, TA 30.
b) Standard - G.E., Type IB-10, Kh 0.6 @120 volt @5 amp tap. ampere tap used 5 and 50.
Determine the accuracy of the meter;
a) Left stator, light load test @ one rev. of the meter disk resulted to 24.05 rev. of the standard.
b) Right stator, light load test @ one rev. of the meter disk resulted to 23.98 rev. of the standard.
c) Series, light load test @ two rev. of the meter resulted to 24.04 rev. of the standard. d) Left stator, full load test @ ten rev. of the meter disk resulted to 24.07 rev. of the standard.