CHAPTER 6: ACTUAL VALUES
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
6–11
6.3
A2 Metering Data
6.3.1
Current Metering
PATH: ACTUAL VALUES
A2 METERING DATA
CURRENT METERING
All measured current values are displayed here. The
CURRENT UNBALANCE
is defined as the
ratio of negative-sequence to positive-sequence current,
I
2
/
I
1
when the motor is
operating at a load (
I
avg
) greater than FLA. If the motor
I
avg
is less than FLA, unbalance is
defined as
I
2
/
I
1
×
I
avg
/ FLA. This derating is necessary to prevent nuisance alarms and
trips when a motor is lightly loaded. The
U/B BIASED MOTOR LOAD
value shows the
equivalent motor heating current caused by the unbalance
k
factor.
When
NOMINAL SYSTEM FREQUENCY
is set to "Variable", or
MOTOR LOAD FILTER INTERVAL
is enabled (set to a non-zero value),
CURRENT UNBALANCE
is calculated from the ratio of
phase current RMS values. Phase angles are ignored. With sinusoidal phase inputs, this
produces values about two times the values produced by calculating I
2
/I
1
. If the ratio of the
smallest phase to largest phase is less than 70%, a fixed value 40%
CURRENT UNBALANCE
is used. Derating still applies when the average load is less than FLA.
CURRENT
[
]
METERING
A:
0
B:
0
C:
0
Amps
Range: 0 to 100000 A
MESSAGE
AVERAGE PHASE
CURRENT: 0 Amps
Range: 0 to 100000 A
MESSAGE
MOTOR LOAD:
0.00 x FLA
Range: 0.00 to 20.00 x FLA
MESSAGE
CURRENT UNBALANCE:
0%
MESSAGE
U/B BIASED MOTOR
LOAD: 0.00 x FLA
Range: 0.00 to 20.00 x FLA
MESSAGE
GROUND CURRENT:
0.00 Amps
Range: 0.00 to 5000.00 A. Not seen if
Ground CT is set as “None”.
MESSAGE
A:
0
B:
0
C:
0
Amps Diff.
Range: 0 to 5000 A. Seen if Phase
Differential CT has 1A/5A
Secondary
Содержание Masoneilan 469 Series
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