BE1-951
Reporting and Alarm Functions
6-19
Figure 6-2. Trip Circuit Voltage And Continuity Monitor
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475A 475A 475A 1.48MW 872KVAR 12:00 03/15/01
38
456A 456A 456A 1.42MW 834KVAR 11:59 03/15/01
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432A 432A 432A 1.35MW 790KVAR 11:58 03/15/01
TRIP CIRCUIT MONITOR
The trip circuit monitor continually monitors the circuit breaker trip circuit for voltage and continuity. A closed
breaker with no voltage detected across the trip contacts can indicate that a trip circuit fuse is open or there
is a loss of continuity in the trip coil circuit. Breaker status (open or closed) is obtained through the breaker
status reporting function (configured by the SB-LOGIC command).
The detector circuit used by the trip circuit monitor is hardwired across the OUT1 contact. This contact is
used in all of the preprogrammed logic schemes as the main trip output. The detector circuit draws less than
1 milliampere of current through the trip coil when the breaker is closed. Figure 6-2 illustrates typical trip
circuit monitor connections for the BE1-951.
If the breaker status reporting function detects a closed breaker and no trip circuit voltage is sensed by the
trip circuit monitor after the appropriate coordination time delay (about 500 msec.), an alarm bit in the
programmable alarms function is set and the OUT1MON BESTlogic variable is set to TRUE.
CAUTION
Applications that place other device inputs in parallel with the breaker trip coil may not
perform as desired. The connection of other devices in parallel with the trip coil causes
a voltage divider to occur when the breaker or trip circuit is open. This may cause false
tripping of the other devices and prevent the BE1-951 trip circuit monitor from reliably
detecting an open circuit. Contact Basler Electric for advice on using this application.
The circuit monitor sensing element has the same rating as the power supply voltage.
If the trip circuit voltage is significantly greater than the power supply voltage (for
example, when using a capacitor trip device), the user should program the BE1-951 to
use one of the other output relays for tripping. In this situation, the trip circuit monitor
function will not be available.
