CHAPTER 5: SETTINGS
469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
5–63
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
UNDERCURRENT TRIP PICKUP
could be set to “0.70” and the
UNDERCURRENT ALARM PICKUP
to “0.75”. If the pump is
always started loaded, the
BLOCK UNDERCURRENT FROM START
settings should be
disabled (programmed as “0”).
The
UNDERCURRENT ALARM DELAY
or
UNDERCURRENT TRIP DELAY
is typically set as quick
as possible, i.e. 1 second.
5.7.5
Current Unbalance
PATH: SETTINGS
S6 CURRENT ELEM.
CURRENT UNBALANCE
For the 469 relay, unbalance is defined as the ratio of negative-sequence to positive-
sequence current,
I
2
/
I
1
, if 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 when a motor is lightly loaded.
The 469 relay employs an alternate method of calculating
CURRENT UNBALANCE
when
NOMINAL SYSTEM FREQUENCY
is set to "Variable" or
MOTOR LOAD FILTER INTERVAL
is
enabled. Refer to section 6.3.1
If enabled, a trip and/or alarm occurs once the unbalance magnitude equals or exceeds
the
CURRENT UNBALANCE ALARM(TRIP) PICKUP
for a period of time specified by the
CURRENT UNBALANCE ALARM(TRIP) DELAY
. If the unbalance level equals or exceeds 40%,
or when
I
avg
≥
25% FLA and current in any one phase is zero, the motor is considered
single phasing and a trip occurs within 2 seconds. Single phasing protection is disabled if
the unbalance trip feature is turned “Off”.
CURRENT
[
]
UNBALANCE
CURRENT UNBALANCE
ALARM: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN ALARM RELAYS:
Alarm
Range: Alarm, Alarm & Auxiliary2,
Alarm & Aux2 & Aux3,
Auxiliary2, Aux2 & Aux3,
Auxiliary3, None
MESSAGE
CURRENT UNBALANCE
ALARM PICKUP: 15%
Range: 4 to 40% in steps of 1
MESSAGE
CURRENT UNBALANCE
ALARM DELAY: 1 s
Range: 1 to 60 s in steps of 1
MESSAGE
CURRENT UNBALANCE
ALARM EVENTS: Off
Range: On, Off
MESSAGE
CURRENT UNBALANCE
TRIP: Off
Range: Off, Latched, Unlatched
MESSAGE
ASSIGN TRIP RELAYS:
Trip
Range: Trip, Trip & Auxiliary2, Trip &
Aux2 & Aux3, Trip & Auxiliary3
MESSAGE
CURRENT UNBALANCE
TRIP PICKUP: 20%
Range: 4 to 40% in steps of 1
MESSAGE
CURRENT UNBALANCE
TRIP DELAY: 1 s
Range: 1 to 60 s in steps of 1
Содержание Masoneilan 469 Series
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