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HRB1684301-01 127
Chapter 15 Verifying accuracy
All meters are tested and verified at the factory in accordance with International
Electrotechnical Commission (IEC) and American National Standards Institute (ANSI)
standards.
Your digital power meter does not require re-calibration. However, in some installations
a final accuracy verification of the meters is required, especially if the meters will be
used for revenue or billing applications.
Testing overview
The most common method for testing meter accuracy is to apply test voltages and
currents from a stable power source and compare the meter’s readings with readings
from a reference device or energy standard.
Accuracy test requirements
Signal and power source
The meter maintains its accuracy during voltage and current signal source variations
but its energy pulsing output needs a stable test signal to help produce accurate test
pulses. The meter’s energy pulsing mechanism needs approximately 10 seconds to
stabilize after every source adjustment.
The meter must be connected to control power in order to conduct accuracy verification
testing. Refer to your meter’s installation documentation for power supply
specifications.
Control equipment
Control equipment is required for counting and timing the pulse outputs from the alarm /
energy pulsing LED or the digital outputs.
• Most standard test benches have an arm equipped with optical sensors to detect
LED pulses (the photodiode circuitry converts detected light into a voltage signal).
• The reference device or energy standard typically has digital inputs that can detect
and count pulses coming from an external source (i.e., the meter’s digital output).
NOTE: The optical sensors on the test bench can be disrupted by strong sources of
ambient light (such as camera flashes, florescent tubes, sunlight reflections, floodlights,
etc). This can cause test errors. Use a hood, if necessary, to block out ambient light.
Environment
The meter should be tested at the same temperature as the testing equipment. The
ideal temperature is about 23 °C (73 °F). Make sure the meter is warmed up sufficiently
before testing.
DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION OR ARC FLASH
Verify the device’s power source meets the specifications for your device’s power
supply.
Failure to follow these instructions will result in death or serious injury.