User's Manual

Testing, Troubleshooting, and Maintenance
CENTRON Meter Technical Reference Guide 8-3
Figure 8.3 TOU Rate Annunciators
Test Mode Annunciator
The CENTRON meter is equipped with a Test Mode LCD annunciator located in
the left portion of the display. This annunciator is enabled when Test Mode is
activated. The word TEST appears on the display and flashes at a steady rate when
test mode is activated. (Available on the C1SD, C1ST, and C1SL.)
Testing with the Infrared Test LED
The CENTRON meter is equipped with an Infrared Test LED (Light Emitting
Diode) which is located on the top of the meter at the 12 o’clock position.
The pulse weight represented by the LED pulses is always 1.0 watt-hour per pulse.
Since the Kh value for the meter is 1.0, make sure the test board is programmed to
accept this Kh value.
1 pulse = 1 Watt-hour as compared to 1 pulse = 7.2 Watt-hours in
Electromechanical meters.
To obtain test uncertainties of 0.01% (plus the uncertainties of the test equipment),
use a minimum of 30 pulses.With a constant load applied (real or phantom), the
LED pulses are compared to the output of a high accuracy watthour standard. This
is accomplished using a compatible optical pickup and a comparator.
Follow these steps to test the Wh LED:
1 Apply a constant delivered watts load (Wapp) to the meter.
2 Verify that the LED pulses properly either by counting the pulses or using a
comparator to compare the pulses from the meter under test to the standard.
To determine the number of pulses per second, use the following equation:
# OF PULSES REQUIRED ON TEST BOARDS
1S & 2S CL200 120V 3S,
240V 3S,
240V 4S
12S & 25S, 2S
CL 320
Full Load 10 7 15
Light Load 10 6 7
Power Factor 10 7 12