TimeThe faultoccursProtectionoperate timeTrip and PickupCCRBRF(50BF)Normal tcbopenMarginRetrip delay t1 tcbopen after re-triptBFPresetMinimum back-up trip delay t2Critical fault clearance time for stabilityANSI05000479_3_en.vsdANSI05000479 V3 EN-USFigure 81: Time sequencet3: Additional time delay tot2 for a second back-up trip TRBU2. In some applications there mightbe a requirement to have separated back-up trip functions, tripping different back-up circuitbreakers.tCBAlarm: Time delay for alarm in case of indication of faulty circuit breaker. There is a binaryinput 52FAIL from the circuit breaker. This signal is activated when internal supervision in thecircuit breaker detect that the circuit breaker is unable to clear fault. This could be the case whengas pressure is low in a SF6 circuit breaker, of others. After the set time an alarm is given, so thatactions can be done to repair the circuit breaker. The time delay for back-up trip is bypassed whenthe 52FAIL is active. Typical setting is 2.0 seconds.tPulse: Trip pulse duration. This setting must be larger than the critical impulse time of circuitbreakers to be tripped from the breaker failure protection. Typical setting is 200 ms.7.11 Stub protection STBPTOC (50STB) IP14515-1 v37.11.1 IdentificationM17108-1 v2Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberStub protection STBPTOC3I>STUBSYMBOL-T V1 EN-US50STB1MRK 511 358-UUS A Section 7Current protection175Application manual
