Operation: CP1SD/T/L Version
74 CENTRON® Polyphase Meter Technical Reference Guide
0
90
270
180
V
B
V
A
V
C
I
A
I
B
I
C
Figure 31: Diagnostic #1 Error Diagram
By comparing the phasor diagram drawn from the information found in the snapshot with
the typical phasor diagram, it becomes clear that the B phase voltage is incorrect. The
correct phasor should be around 120°, not 300° where the phasor currently is. Since the
phasor is approximately 180° off, this most likely represents a polarity problem with the B
phase voltage circuit. Also note that diagnostic counter d1 has incremented to “001”.
SiteScan Diagnostic #2
The purpose of this diagnostic is to verify that each individual phase maintains an
acceptable voltage level with respect to phase A. Because Phase A is present in all the
configurations, it is chosen as the reference level. This diagnostic check may indicate one or
more of the following problems:
Loss of phase voltage
Incorrect voltage transformer ratio
Shorted voltage transformer windings
Incorrect phase voltage
Internal meter measurement malfunction
Faulty site wiring
The percentage of deviation tolerated from phase A voltage is the user-defined parameter
used for this test. All other phases are compared to phase A, to see if it is within the defined
voltage tolerance.
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