Operation: CP1SD/T/L Version
CENTRON® Polyphase Meter Technical Reference Guide
87
Solution 3
Install the latest test board software revision. A test board ideally should recognize no new
test pulses after the completion of a test until jogging, ramping, and settling time have all
transpired. Settling time should be programmed for three to six seconds. There is nothing to
be gained by using settling times greater than six seconds.
Recommended Test Setup for Minimizing Test Time
The following settings are recommended for obtaining test uncertainties of less than 0.1%
and at minimum test times:
1
Program the test board settling time for five seconds.
2
Program the meter and test board for a small test constant, Kt, in some convenient
fractional value of the traditional Kh. For this example, 1/12 of the traditional Kh of the
equivalent electromechanical meter is used. (The use of decimal values may be
preferred for simplification of math.)
3
Use 12 pulses (1 rev) for FL.
4
Use 12 pulses for PF.
5
Use 1 pulse for LL.
6
For element tests, the FL and PF pulses can be divided by the number of elements,
always rounding up for fractional values.
The total test time for a series FL, PF, LL sequence can be shortened by more than one
minute compared to the time required for an electromechanical meter or a solid-state meter
using the equivalent test constants. If LL element tests are used, the time savings will be
much greater.
Recommendations for Minimum Variability
The variability of testing a CENTRON Polyphase meter can be reduced by lengthening the
test times (using more pulses). Doubling or tripling the recommended minimum test time
will reduce the variability by a factor of two or three. Very little improvement is realized by
running longer than about 45 seconds for each test.
Demand Testing
Testing consists of comparing the readings displayed on the CENTRON Polyphase meter to
the actual demand as determined using a high-accuracy RMS responding reference standard.
The standard should have pulse outputs proportional to Wh/pulse (or VAh/pulse).
Pulses from the reference standard are accumulated over one demand interval, and then the
total pulse count representing watt-hours or volt-ampere-hours is converted to an average
demand value using the formulas in Demand Calculations.
Because of the high accuracy of the CENTRON Polyphase meter, the following is the
recommended procedure for testing these meters.
