Schneider Electric PM870 Manual De Usuario
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).
vice versa).
•
PT secondary leads are swapped (A-phase lead on C-phase terminal and
vice versa).
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.
than about half of the expected magnitude.
•
PF can be any value, probably a low leading
value.
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
than about half of the expected magnitude
•
PF can be any value, probably a low leading
value
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
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
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.
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
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.
phase that reads 0.