ABB RER620 Technical Manual

Section 4 1MAC309294-MB F
Protection functions
138 RER620
Technical Manual
4.1.4.2 Function block
Figure 57: Function block
4.1.4.3 Functionality
The ground-fault function 67/51N and 67/50N is used as directional ground-fault
protection for feeders.
There are three different polarization signals - measured zero sequence voltage, calculated
zero sequence voltage and negative sequence voltage. The function picks up and trips
when the zero sequence current (I
0
) and zero sequence voltage (-V
0
) exceed the set limits
and the angle between them is inside the set operating sector. The function also picks up
and trips when the negative sequence current (I
2
) and negative sequence voltage (-V
2
)
exceed the set limits and the angle between them is inside the set operating sector. The trip
time characteristic for low stage (67/51N and 67/50N-1) and high stage (67/50N-2) can be
selected to be either definite time (DT) or inverse definite minimum time (IDMT).
In the DT mode, the function trips after a predefined trip time and resets when the fault
current disappears. The IDMT mode provides current-dependent timer characteristics.
The function contains a blocking functionality. It is possible to block function outputs,
timers or the function itself, if desired.
4.1.4.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are Enable and Disable.
The operation of directional earth-fault protection can be described by using a module
diagram. All the modules in the diagram are explained in the next sections.
67/51N
PICKUP
TRIP
BLOCK
ENA_MULT
RCA_CTL
67/50N-2
PICKUP
TRIP
BLOCK
ENA_MULT
RCA_CTL
67/50N-1
PICKUP
TRIP
BLOCK
ENA_MULT
RCA_CTL
V0/VG/V2 V0/VG/V2 V0/VG/V2
I0/IG/I2
I0/IG/I2
I0/IG/I2

ABB RER620 Specifications

General

Brand	ABB
Model	RER620
Category	Controller
Language	English