Filter
Top Products
PowerLogic
TM
Series 800 Power Meter 63230-500-225A2
Appendix A—Instrument Transformer Wiring: Troubleshooting Tables 3/2011
© 2011 Schneider Electric All Rights Reserved
78
Field Example
Readings from a 4-wire system
•
•
•
•
•
•
•
•
•
•
•
•
•
•
lag to lead fluctuating
Troubleshooting Diagnosis
• Power factors cannot be correct .
• None of the “Section II” symptoms exist, so proceed to the 4-wire troubleshooting
(“Section IV”).
• Cannot calculate kW because 3-phase power factor cannot be right, so calculate kVA
instead.
• Calculated kVA =
=
=
• Power meter reading is essentially zero compared to this value.
• 4-wire Case E looks similar.
• Since the PTs were connected to other power meters which were reading correctly,
suspect two CT leads swapped.
• Since A-phase power factor is the only one that has a normal looking lagging value,
suspect B and C-phase CT leads may be swapped.
• After swapping B and C-phase CT leads, all readings went to the expected values;
problem solved.
kW 25=
kVAR 15–=
kVA 27=
I
A
904A=
I
B
910A=
I
C
931A=
I
3Avg
908A=
V
AB
495V=
V
BC
491V=
V
CA
491V=
V
AN
287V=
V
BN
287V=
V
CN
284V=
PF
3Avg
0.75=
0.22
3V
ab
I
3Avg
1000
1.732 495 908 1000
778
kVA