1561MRS 751802-MUMProtection RelayTechnical Reference Manual, Standard ConfigurationsREX 521The settings for breaker failure are set separately for each protection function. Forexample, to set the CBFP time for 3I>> go toMain menu\Protection\3I>>\Control setting where it is possible toset the “CBFP time” from 100 ms to 1000 ms. The control parameter “Trip pulse”sets the width of the trip output signal, but also of the CBFP output signal.The CBFP signals from the protection functions are routed to the output signals viathe output switchgroups. These settings can be found inMain menu\Configuration\Output SWGRP\CBFP. When the two-stageovercurrent, the two-stage directional earth-fault, the unbalance and thermaloverload protection are selected, the checksum for CBFP will be 221.The CBFP signal is then connected to any of the output relays viaMain menu\Configuration\Output Signals\, and in this example thecircuit-breaker failure signal is connected to the power output 1, PO1.10.2.5.7. Trip-circuit supervisionThe trip-circuit supervision is available for the HSPO1 relay. If the resistance of thetrip circuit exceeds a certain limit, for instance due to a bad contact or oxidation, thesupervision function will be activated and a trip-circuit supervision alarm signal willbe provided after an adjustable delay time. The settings for the function can be foundin Main menu\Cond. monit.\TCS\.To avoid unnecessary alarms the trip-circuit supervision can be blocked by the BSsignal, which disables the supervision output when the circuit breaker is open. TheBS signal is configured to be operated by the “CB pos. open” status from the selecteddigital input. The BS signal can be connected via the switchgroup inMain menu\Input SWGRP\TCS\. The default setting of the parameter is ”Notin use”.Another solution is to use an external resistor to prevent the TCS alarm. Please referto Technical Reference Manual, General (1MRS 751108-MUM) for moreinformation about the trip-circuit supervision.
