Woodward highprotec MRI4, User Manual

Page: 580 / 727

Supervision
Commissioning Example: Supervision Scheme 50BF
Object to Be Tested:
Test of the breaker failure protection (Supervision Scheme 50BF).
Necessary Means:
Current source;
Ammeter; and
Timer.
When testing, the applied test current must always be higher than the tripping
threshold
»I-CBF«. If the test current falls below the threshold while the breaker
is in the “Off” position, no pickup will be generated.
Procedure
(Single-Phase):
For testing the tripping time of the CBF protection, a test current has to be higher than the threshold value of one of
the current protection modules that are assigned to trigger the CBF protection. The CBF trip delay can be measured
from the time when one of the triggering inputs becomes active to the time when the CBF protection trip is asserted.
To avoid wiring errors, checked to make sure the breaker in the upstream system switches off.
The time, measured by the timer, should be in line with the specified tolerances.
Successful Test Result:
The actual times measured comply with the setpoint times. The breaker in the higher-level section switches off.
Re-connect the control cable to the breaker!
TCS - Trip Circuit Supervision [74TC]
Available elements:
TCS
The trip circuit monitoring is used for monitoring if the trip circuit is ready for operations. The monitoring can be
fulfilled in two ways. The first assumes only »
Aux On (52a)«
is used in the trip circuit. The second assumes that, in
addition to »
Aux On (52a)
, »
Aux Off(52b)«
is also used for the circuit monitoring.
With »
Aux On (52a)
, only in the trip circuit, the monitoring is only effective when the breaker is closed while if both
»
Aux On (52a)
, and »
Aux Off(52b)«
are used, the trip circuit will be monitored all time as long as the control power
is on.
Note that the digital inputs used for this purpose must be configured properly based on the trip circuit control
voltage. If the trip circuit is detected broken, an alarm will be issued with a specified delay, which must be longer
than the time when a trip contact is closed to the time when the breaker status is clearly recognized by the relay.
In Slot 1 has 2 digital inputs, each of which has a separate root (contact
separation) for the trip circuit supervision.
580 MRI4 DOK-HB-MRI4-2E