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63230-500-225A2 PowerLogic
TM
Series 800 Power Meter
3/2011 Appendix A—Instrument Transformer Wiring: Troubleshooting Tables
© 2011 Schneider Electric All Rights Reserved
75
Section II: 3-Wire System Troubleshooting
Section II—Case A
Symptoms: 3-Wire Possible Causes
• Currents and voltages approximately balanced
• kW = near 0
• kVAR = near 0
• PF can be any value, probably fluctuating
• CT secondary leads are swapped (A-phase lead on C-phase terminal and
vice versa).
• PT secondary leads are swapped (A-phase lead on C-phase terminal and
vice versa).
Section II—Case B
Symptoms: 3-Wire Possible Causes
• Phase B current is higher than A and C
(except in System Type 31).
• kVA = about half of the expected magnitude
• kW and kVAR can be positive or negative, less
than about half of the expected magnitude.
• PF can be any value, probably a low leading
value.
• One CT polarity is backwards.
3
Section II—Case C
Symptoms: 3-Wire Possible Causes
• is higher than and
• kVA = about half of the expected magnitude
• kW and kVAR can be positive or negative, less
than about half of the expected magnitude
• PF can be any value, probably a low leading
value
• One PT polarity is backwards.
V
CA
3
V
AB
V
BC
Section II—Case D
Symptoms: 3-Wire Possible Causes
• kW = 0 or low, with magnitude less than kVAR
• kVAR = positive or negative with magnitude of
close to what is expected for kW
• kVA = expected magnitude
• PF = near 0 up to about 0.7 lead
• Either the two voltage leads are swapped OR the two current leads are
swapped AND one instrument transformer has backwards polarity.
(look for high or phase B current = high)
• The power meter is metering a purely capacitive load (this is unusual); in
this case kW and kVAR will be positive and PF will be near 0 lead.
V
CA
3=
3
Section II—Case E
Symptoms: 3-Wire Possible Causes
• One phase current reads 0
• kVA = about 1/2 of the expected value
• kW, kVAR, and power factor can be positive or
negative of any value
• The CT on the phase that reads 0 is short-circuited.
• Less than 2% current (based on CT ratio) flowing through the CT on the
phase that reads 0.