User's Manual

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Contact Elster Electricity for information
30 November 2006 5-9
REX Meter
Technical Manual 5 Testing
Voltage should be applied to the meter for at least 10 seconds before
measuring, allowing the power supply circuitry to stabilize.
Watthour Testing
To maintain compatibility between procedures for testing electronic and
electromechanical meters, it is recommended that the REX meter be tested at
the standard test points. These test points are described in Table 5-5.
Table 5-5. Watthour test points
Whereas electromechanical meters have adjustments to calibrate the meter at
all three test points, the REX meter is calibrated in the factory.
Elster Electricity provides the factory calibration data in a report.
To test the REX meter at the standard test points, the following procedure
should be used:
1. Verify the meter calibration at full load using the formula for calculating
meter accuracy. See “Calculating meter accuracy” on page 5-8 to
determine the percent accuracy.
2. Verify the meter calibration at light load using the same formula in step
1.
3. Verify the calibration of the meter at full load with lagging power factor
using the same formula in step 1.
4. Check for creeping at the rated voltage level with no current. The meter
must produce one full K
h
pulse within 10 minutes to be considered
creeping, with creep being defined as continuous output pulses from
the meter with normal operating voltage but the load terminals open
circuited.
12S, 200 A 120 V 30 A 120 Wh/minute
12S, 320 A 120 V 50 A 200 Wh/minute
Form Test voltage Test current K
h
pulses per minute
Test point Definition
Full load 100% of the nameplate test amperes, test voltage, and
rated frequency at unity power factor
Light load 10% of the nameplate test amperes, test voltage, and rated
frequency at unity power factory
Lagging power
factor
100% of the nameplate test amperes, test voltage, and
rated frequency at 0.5 lagging power factor (current lagging
voltage by 60 ° phase angle)