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Verifying accuracy
Verifying accuracy
Overview of meter 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 typically 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.
Accuracy test requirements
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.
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.
DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH
Failure to follow these instructions will result in death or serious injury.
Verify the device’s power source meets the specifications for your device’s
power supply.
Control equipment
Control equipment is required for counting and timing the energy pulse outputs
from a visible LED, infrared LED or onboard digital output.
• 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
onboard 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 ºC (73 ºF). Make sure the meter is warmed up
sufficiently before testing.
206 7EN05-0390-00