Basler Electric BE1-50/51B-240 - Manual (Page 20)

12 9252000790 Rev B
When sufficient current is sensed by the relay, the microprocessor is active and executing code, and the
Active/Pickup LED is green. When the sensed current decreases below the operating threshold,
microprocessor operation is interrupted and the Active/Pickup LED turns off. A watchdog circuit resets the
microprocessor program when code execution is interrupted.
Power-off sensing circuits measure the voltage across a capacitor at power-down and power-up. These
circuits determine how long power has been removed based on the difference voltage and the circuit’s
RC time constant. This provides information from the integrating reset function even when power has
been entirely removed.
The microprocessor performs the program operations based on the inputs and the internal software
program. When the sensed current exceeds the TIME PICKUP setting, the ACTIVE/PICKUP LED turns
from green to red. The 51 contact is closed in accordance with the TIME characteristic equation or if the
sensed current exceeds the INST PICKUP setting. Likewise, sensed current exceeding the Instantaneous
Overcurrent Pickup selector switch setting causes the 50 Trip output contacts to close.
Outputs
Two sets of normally-open output contacts rated for tripping duty are provided. The first is used by the
time overcurrent (51) element. The second is used by the instantaneous overcurrent (50). A system circuit
breaker controlled by the 51 or 50 output contacts can be manually tripped by connecting a jumper across
the Time Overcurrent Manual Trip jacks or the Instantaneous Overcurrent Manual Trip jacks. Current flow
in a trip circuit is indicated by operation of the corresponding target. The targets will not operate without
adequate relay operating power.
Warning!
Trip circuit voltage is present at the front panel trip jacks. When
shorting the trip jacks, use insulated jumpers to avoid contact with
these voltages.
Target Indicators
Gravity-latched, manually-reset, current-operated target indicators are provided for the time overcurrent
(51) trip output and the instantaneous overcurrent (50) trip output. The level of trip circuit current required
to operate each target is individually controlled by a circuit board jumper. The minimum operating current
range can be set for 80 to 200 milliamperes or 0.9 to 2.25 amperes. See the Controls and Indicators
chapter for jumper locations and function assignments.
Functional Description BE1-50/51B-240