User's Manual

Operation: CVSO OpenWay Register
CENTRON® OpenWay™ Meter Technical Reference Guide 57
Recommendations
Erroneous test results caused by the problems previously described can probably be
corrected by implementing one of the following suggestions. Even if there are no bad
readings, Solution 3 can cut the total test time significantly without sacrificing test
verification certainty. The suggested solutions are:
1 Change the test sequence to avoid jogging before the light-load test.
2 Upgrade the test board to meet the requirements listed previously.
3 Program the meter and test board for a small test constant. This will avoid jogging and
also give the added benefit of shorter test time.
Solution 1
This is the preferred solution, since it results in shorter test times and can be implemented
simply by programming the meter for a smaller test constant and settling the test board
accordingly.
The CENTRON Polyphase and most other solid-state meters have the capability of being
programmed for a much smaller test constant (Kt), such as one-tenth or one-twelfth of the
energy required for one “disk revolution” of the meter. With the test pulses running 10 to 12
times faster, there is the possibility of shortening the test time considerably, but not by a
factor of 10 or 12. It still takes a finite amount of time to obtain meaningful results.
Solution 2
Change the test sequence so that the LL test is first, followed by the PF test and then the FL
test. This should prevent all jogging from occurring between tests and will probably
eliminate the erroneous readings. This is the quickest solution to implement since it requires
no changes to the test board or the meter.
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.
Draft