C Urrent U Nbalance - GE 469 Instruction Manual

CHAPTER 5: SETTINGS
5.7.5 Current Unbalance
 CURRENT
UNBALANCE
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
For example, if a pump is cooled by the liquid it pumps, loss of load may mean that the
pump overheats. In this case, enable the undercurrent feature. If the motor loading should
never fall below 0.75 × FLA, even for short durations, the
could be set to "0.70" and the
always started loaded, the
disabled (programmed as "0").
The
UNDERCURRENT ALARM DELAY
as possible, i.e. 1 second.

PATH: SETTINGS S6 CURRENT ELEM.
[] CURRENT UNBALANCE
ALARM: Off
ASSIGN ALARM RELAYS:
MESSAGE
Alarm
CURRENT UNBALANCE
MESSAGE
ALARM PICKUP: 15%
CURRENT UNBALANCE
MESSAGE
ALARM DELAY: 1 s
CURRENT UNBALANCE
MESSAGE
ALARM EVENTS: Off
CURRENT UNBALANCE
MESSAGE
TRIP: Off
ASSIGN TRIP RELAYS:
MESSAGE
Trip
CURRENT UNBALANCE
MESSAGE
TRIP PICKUP: 20%
CURRENT UNBALANCE
MESSAGE
TRIP DELAY: 1 s
For the 469 relay, unbalance is defined as the ratio of negative-sequence to positive-
sequence current, I / I , if the motor is operating at a load (I
2 1
motor I is less than FLA, unbalance is defined as I
avg
necessary to prevent nuisance alarms when a motor is lightly loaded.
The 469 relay employs an alternate method of calculating
NOMINAL SYSTEM FREQUENCY
enabled. Refer to section 6.3.1 Current Metering on page 6–11.
If enabled, a trip and/or alarm occurs once the unbalance magnitude equals or exceeds
the
CURRENT UNBALANCE ALARM(TRIP) PICKUP
CURRENT UNBALANCE ALARM(TRIP) DELAY
or when I ≥ 25% FLA and current in any one phase is zero, the motor is considered
avg
single phasing and a trip occurs within 2 seconds. Single phasing protection is disabled if
the unbalance trip feature is turned "Off".
UNDERCURRENT ALARM PICKUP
BLOCK UNDERCURRENT FROM START
or
UNDERCURRENT TRIP DELAY

CURRENT UNBALANCE
2
is set to "Variable" or
MOTOR LOAD FILTER INTERVAL
for a period of time specified by the
. If the unbalance level equals or exceeds 40%,
UNDERCURRENT TRIP PICKUP
to "0.75". If the pump is
settings should be
is typically set as quick
Range: Off, Latched, Unlatched
Range: Alarm, Alarm & Auxiliary2,
Alarm & Aux2 & Aux3,
Auxiliary2, Aux2 & Aux3,
Auxiliary3, None
Range: 4 to 40% in steps of 1
Range: 1 to 60 s in steps of 1
Range: On, Off
Range: Off, Latched, Unlatched
Range: Trip, Trip & Auxiliary2, Trip &
Aux2 & Aux3, Trip & Auxiliary3
Range: 4 to 40% in steps of 1
Range: 1 to 60 s in steps of 1
) greater than FLA. If the
avg
/ I × I / FLA. This derating is
1 avg
CURRENT UNBALANCE
when
is
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