Operation: CP1SD/T/L Version
78
CENTRON® Polyphase Meter Technical Reference Guide
SiteScan Diagnostic #4
The purpose of this diagnostic is to verify that the current elements are sensing and
receiving the correct current for each phase. It is basically a power factor check diagnostic.
This diagnostic check may indicate one or more of the following problems:
Poor load power factor conditions
Poor system conditions
Malfunctioning system equipment
Diagnostic #1 must be enabled and passed for this diagnostic to be enabled, so that the
system can assume all the phasors are in the relatively correct orientation. Each phase must
also exceed a configured minimum current threshold in order for it to be tested. Then the
user-defined angle tolerance is the parameter used to check the phasors.
Low End Threshold Current
The low end threshold current for Diagnostic #4 is adjustable based upon the class of the
meter from 0.5% of class to 5% of class.
Phase Angle Displacement Check
Diagnostic #1 must be enabled and must pass for Diagnostic #4 to be enabled and check for
a problem. This will allow the system to make the assumption that all the phasors are in the
relatively correct orientation and that there is no wiring problem. Since the voltage angles
passed Diagnostic #1, the meter will assign the voltage phasors to be constant at the typical
phasor angle.
If Diagnostic #1 passes, the meter will then determine the angle of each current phasor with
respect to VA for Diagnostic #4. The meter will monitor each current phasor angle for
validity with respect to the meter’s form number and service type. Diagnostic #4 will take
the “typical” phasor diagram at unity PF for a particular form number and service type and
place a user-defined envelope around each current phasor, where the actual phasor must be
found for the diagnostic check to pass.
