Typical Sources Of Test Errors; Accuracy Verification Test Points - Siemens US2:9810T24V User Manual

Verifying accuracy
NOTE: If accuracy verification reveals inaccuracies in your meter, they may be caused by typical
sources of test errors. If there are no sources of test errors present, please contact your local
Siemens Industry representative.

Typical sources of test errors

If you see excessive errors during accuracy testing, examine your test setup and test procedures
to eliminate typical sources of measurement errors.
Typical sources of accuracy verification testing errors include:
• Loose connections of voltage or current circuits, often caused by worn-out contacts or
terminals. Inspect terminals of test equipment, cables, test harness and the meter under test.
• Meter ambient temperature is significantly different than 23 °C (73 °F).
• Floating (ungrounded) neutral voltage terminal in any configuration with unbalanced phase
voltages.
• Inadequate meter control power, resulting in the meter resetting during the test procedure.
• Ambient light interference or sensitivity issues with the optical sensor.
• Unstable power source causing energy pulsing fluctuations.
• Incorrect test setup: not all phases connected to the reference device or the energy standard.
All phases connected to the meter under test should also be connected to the reference
meter/standard.
• Moisture (condensing humidity), debris or pollution present in the meter under test.

Accuracy verification test points

The meter should be tested at full and light loads and at lagging (inductive) power factors to help
ensure testing over the entire range of the meter.
The test amperage and voltage input rating are labeled on the meter. Refer to the installation
guide or data sheet for your meter's nominal current, voltage and frequency specifications.
Watt-hour test point Sample accuracy verification test point
Full load
Light load
Inductive load
(lagging power
factor)
VAR-hour test point Sample accuracy verification test point
Full load
287
100% to 200% of the nominal current, 100% of the nominal voltage and
nominal frequency at unity power factor or one (1).
10% of the nominal current, 100% of the nominal voltage and nominal
frequency at unity power factor or one (1).
100% of the nominal current, 100% of the nominal voltage and nominal
frequency at 0.50 lagging power factor (current lagging voltage by 60°
phase angle).
100% to 200% of the nominal current, 100% of the nominal voltage and
nominal frequency at zero power factor (current lagging voltage by 90°
phase angle).
9810 series - User manual
7EN05-0390-08