ABB REF615 L User Manual

in transformer and LV-side busbar faults. The high-set stage PH3HPTOC operates
instantaneously, making use of current selectivity only in the transformer HV-side
faults. If there is a possibility that the fault current can also be fed from the LV-side
up to the HV-side, the transformer must also be equipped with an LV-side
overcurrent protection. Inrush current detectors are used in startup situations to
multiply the current start value setting in each particular IED where the inrush
current can occur. The overcurrent- and contact-based circuit breaker failure
protection CCBRBRF is used to confirm the protection scheme in case of circuit
breaker malfunction.
MF
MF
MF
MF MF MF MF
MF
MF
MEASUREMENT
INCOMING
GNIOGTUOGNIOGTUOEIT_SUBEIT-SUBGNIOGTUOGNIOGTUO
INCOMING
MEASUREMENT
PH3LPTOC
PH3HPTOC
INRPHAR
PH3LPTOC
PH3HPTOC
CCBRBRF
PH3LPTOC
PH3HPTOC
CCBRBRF
INRPHAR
PH3LPTOC
PH3HPTOC
INRPHAR
PH3LPTOC
PH3HPTOC
CCBRBRF
INRPHAR
GUID-46F45186-75AC-4487-886A-AA8369F6EF9F V1 EN
Figure 80: Example of traditional time-selective transformer overcurrent
protection
The operating times of the main and backup overcurrent protection of the above
scheme become quite long. This applies especially in the busbar faults and also in
the transformer LV-terminal faults. To improve the performance of the above
scheme, a multiple-stage overcurrent protection with a reverse blocking is
proposed.
Figure 73 shows this arrangement.
Transformer and busbar overcurrent protection with reverse blocking
principle
By implementing a full set of overcurrent protection stages and blocking channels
between the protection stages of the incoming feeders, bus-tie and outgoing
feeders, it is possible to accelerate the operation of the overcurrent protection in the
busbar and transformer LV-side faults without impairing the selectivity. Also, the
security degree of the busbar protection is increased, because there is now a
dedicated, selective and fast busbar protection functionality which is based on the
blockable overcurrent protection principle. The additional time-selective stages on
Section 4 1YHT530004D05 D
Protection functions
166 615 series
Technical Manual

ABB REF615 L Specifications

General

Type	Feeder Protection Relay
Rated Frequency	50/60 Hz
Weight	Approx. 1.5 kg
Communication Protocols	IEC 61850, Modbus RTU, DNP3
Protection Functions	Overcurrent, Earth fault, Thermal overload, Under/Over voltage, Under/Over frequency
Enclosure	IP20