Typical Sources Of Test Errors; Accuracy Verification Test Points - Siemens 9810 Series User Manual

Typical sources of test errors

Accuracy verification test points

210
Where:
• EM = energy measured by the meter under test
• ES = energy measured by the reference device or energy standard.
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.
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.
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 sheet or data sheet for your meter's nominal current, voltage and
frequency specifications.
Watt-hour test point Sample accuracy verification test point
Full load 100% to 200% of the nominal current, 100% of the nominal voltage and
nominal frequency at unity power factor or one (1).
Light load 10% of the nominal current, 100% of the nominal voltage and nominal
frequency at unity power factor or one (1).
Inductive load (lagging 100% of the nominal current, 100% of the nominal voltage and nominal
power factor) frequency at 0.50 lagging power factor (current lagging voltage by 60°
phase angle).
VAR-hour test point Sample accuracy verification test point
Full load 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).
Light load 10% of the nominal current, 100% of the nominal voltage and nominal
frequency at zero power factor (current lagging voltage by 90° phase
angle).
Inductive load (lagging 100% of the nominal current, 100% of the nominal voltage and nominal
power factor) frequency at 0.87 lagging power factor (current lagging voltage by 30°
phase angle).
Verifying accuracy
7EN05-0390-00