8/10/2019 Meter Testing
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Technical manual 6-10 Testing
Risk of personal injury or death!Use only authorized personnel
and proper test procedures to test meteringequipment. Dangerous
voltages are present. Personal injury, death, orequipment damage
can result if safety precautions are not followed.
To set up the A1800 ALPHA meter for testing:
1. Install the meter in the stable mounting fixture.
2. Place the precision Wh or varh reference standard and
precision voltage and currenttransformers (as required) in series
with the meter being tested.
If voltage transformers are not required, then the meter source
voltage should beplaced in parallel with the Wh or VARh reference
standards. See Appendix D, Wiringdiagrams, for appropriate wiring
diagrams for the A1800 ALPHA meter.
3. Connect the control equipment for switching the source
voltage to the precisionreference standard.
4. Connect the measuring equipment for counting the standards
output pulses.5. Apply the rated test current and voltage to the
terminals of the meter.
Meter testing
Since no adjustments are required for the A1800 ALPHA meter in
the field, meter testing isdone primarily to verify that the meter
is operating within its specifications. Typically,
meterspecifications are verified by checking the meter calibration.
The accuracy of theA1800 ALPHA meter remains consistent over a wide
range of ambient temperatures.Nevertheless, for precise test
results, meters should be tested in an environment where themeter
and test equipment are at the same ambient temperature, ideally 22
C (72 F).
The test voltage should be applied to the meter for at least ten
seconds prior to making testmeasurements. This allows the power
supply circuitry to stabilize. When testing meters for
Class 0.2 accuracy, a test cycle time of at least one minute is
recommended at Inand withPF = 1.0. When using current values lower
than Infor testing, test errors may occur becausenot enough time is
allowed for the test. When using a lower test In, increase the test
timeproportionally.
The preferred test method is to apply full 3-phase voltage and
current to both the meterand the precision reference standard.
Nevertheless, if required, polyphase meters can betested with
single phase loading. Single phase loading is done by connecting
the voltageinputs in parallel and the current sensors in series to
combine element operation. Theaccuracy test results for single
phase and polyphase loading will be virtually identical andwell
within A1800 ALPHA meter specifications.
Using relay outputs for testing. The relay outputs can be used
instead of the LED to testmeter calibration. To do so, the relay
outputs need to be configured for pulse output. When
using the relay outputs for testing, testing t ime should exceed
20 seconds for accurateresults at normal test current values of
Ibor In. If more accurate testing is required, uselonger testing
times. If precision testing is required, testing times should be as
long as ittakes to attain a stable accuracy level when comparing
the meter under test to theprecision standard. The testing time may
vary because of the characteristics of theprecision reference
standard and the amount of power flowing through the test
circuits.Some experimentation may be required to determine the
testing time needed to reach astable accuracy level.
Using LCD pulse count for testing. For test shops that do not
have photoelectric pulsesensors and related counters and do not
want to use relay outputs for testing, the LCD canprovide a pulse
count that reflects the energy measured during a test. Use the LCD
pulsecount to determine the energy measured during the test cycle
and compare it with theenergy delivered by precision reference
standard.
