Schneider Electric PM810 Manual De Usuario
PowerLogic
TM
Series 800 Power Meter
63230-500-225A2
Appendix A—Instrument Transformer Wiring: Troubleshooting Tables
3/2011
© 2011 Schneider Electric All Rights Reserved
74
Section I: Common Problems for 3-Wire and 4-Wire Systems
Section I—Case A
Symptoms: 3-Wire and 4-Wire
Possible Causes
•
Zero amps
•
Zero kW, kVAR, kVA
•
CT secondaries shorted.
•
Less than 2% load on power meter based on CT ratio.
Example: with 100/5 CT's, at least 2A must flow through CT window for power
meter to “wake up.”
meter to “wake up.”
Section I—Case B
Symptoms: 3-Wire and 4-Wire
Possible Causes
•
Negative kW of expected magnitude
•
Positive kVAR
•
Normal lagging power factor
•
All three CT polarities backwards; could be CTs are physically mounted
with primary polarity mark toward the load instead of toward source or
secondary leads swapped.
with primary polarity mark toward the load instead of toward source or
secondary leads swapped.
•
All three PT polarities backwards; again, could be on primary or secondary.
NOTE: Experience shows CTs are usually the problem.
Section I—Case C
Symptoms: 3-Wire and 4-Wire
Possible Causes
•
Frequency is an abnormal value; may or may
not be a multiple of 50/60 Hz.
not be a multiple of 50/60 Hz.
•
PTs primary and/or secondary neutral common not grounded (values as
high as 275 Hz and as low as 10 Hz have been seen).
high as 275 Hz and as low as 10 Hz have been seen).
•
System grounding problem at the power distribution transformer (such as
utility transformer), though this is not likely.
utility transformer), though this is not likely.