Software

Software
22
Meter
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Until now, the usual method for testing of energy meters has been to use a stabilized, but
not very accurate, power source, in combination with a high-precision reference meter.
OMICRON's approach significantly simplifies meter testing. By using state-of-the-art hardware
technology, OMICRON provides test sets that are so accurate and stable, that the signal source
itself becomes the reference and make a reference meter unnecessary.
The CMC test sets not only provide the test signals, but also have inputs for the meter pulses
allowing closed loop testing. To this end, optical scanning heads for capturing pulses emitted
by the meters (infrared LEDs) are available. Meter allows for manual or automated testing of
energy meters.
Each line of the test table represents a test point, which can be run in one of the following
modes:
• Load test Accuracy of measurement unit (time power method)
• Mechanism test Accuracy of entire meter including display
• Gated Mechanism test Testing internal meter registers
• Injection test Quick check (wiring, sense of rotation)
• No-load test No start-up at zero load
• Creep test Start-up at low loads
In the columns of the table the individual test parameters, the set assessment criteria (tolerance,
nominal behavior), and the result of the test, including the assessment (passed or failed)
are displayed. For multifunctional meters, or meters with two directions of rotation, a table
per test function is available (multiple tabs). Test lines can be repeated several times. In this
case the standard deviation is displayed together with the meter error, which allows conclusions
of the correctness of the test itself. Single test steps (e.g. those assessed as failed) can be
repeated after a test run is finished, without the need for repeating the whole test.
For testing the behavior of meters with harmonics or DC components, the following current
signal waveforms are available:
• Sine
• Sine + Harmonics
• Sine + DC
The test quantities are displayed graphically by means of the voltage, current and power
vector diagrams.
The test can be performed with any balanced or unbalanced load for:
• Single phase meters (or a single measurement element of a 3-phase meter)
• 3-wire meters
• 4-wire meters
In a detail view, all parameters can be specified independently for each phase. Apparent,
active and reactive power is indicated for each phase and the whole rotary system. Testing of
the following meter functions is supported:
• Wh importing/exporting
• VArh importing/exporting
• VAh
• I 2 h and V 2 h (load/no-load losses of transformers)
• Qh (quantity hour)
The results of an automatic test are clearly summed up in a tabular test report (one line per
test point). For a manual test, generating any test quantities, without defining a complete test
procedure, can quickly check the correct functioning of meters. In this mode the constant of a
meter can also be determined, in case it is not known or if there are doubts about it.
Also operation in conjunction with an external reference meter is possible: When testing with
a reference meter, the CMC is used as a current and voltage source. During a load test, the
pulses of the meter under test as well as those of the reference meter are registered. The latter
form the reference for error calculation.
Furthermore, testing against a 0.02 or 0.01 % reference before a test is run, using the same
test points, can eliminate errors of the CMC by loading correction values.