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
Summary of Contents for RER620
Page 2: ......
Page 22: ...Section 1MAC309294 MB F 16 RER620 Technical Manual ...
Page 88: ...Section 3 1MAC309294 MB F Basic functions 82 RER620 Technical Manual ...
Page 278: ...Section 4 1MAC309294 MB F Protection functions 272 RER620 Technical Manual ...
Page 362: ...Section 5 1MAC309294 MB F Control functions 356 RER620 Technical Manual ...
Page 418: ...Section 7 1MAC309294 MB F Measurement functions 412 RER620 Technical Manual ...
Page 428: ...Section 8 1MAC309294 MB F Recording functions 422 RER620 Technical Manual ...
Page 464: ...Section 9 1MAC309294 MB F Other functions 458 RER620 Technical Manual ...
Page 554: ...Section 10 1MAC309294 MB F General function block features 548 RER620 Technical Manual ...
Page 568: ...Section 12 1MAC309294 MB F Relay physical connections 562 RER620 Technical Manual ...
Page 574: ...Section 13 1MAC309294 MB F Technical data 568 RER620 Technical Manual ...
Page 576: ...Section 14 1MAC309294 MB F Relay and functionality tests 570 RER620 Technical Manual ...
Page 578: ...Section 15 1MAC309294 MB F Applicable standards and regulations 572 RER620 Technical Manual ...
Page 582: ...Section 16 1MAC309294 MB F Glossary 576 RER620 Technical Manual ...
Page 583: ......