1MAC050144-MB C
Section 4
Protection functions
615 series ANSI
163
Technical Manual
4.1.5
Sensitive ground-fault protection 50SEF
4.1.5.1
Identification
4.1.5.2
Function block
Figure 70:
Function block
4.1.5.3
Functionality
A small percentage of the ground faults have very large impedance. It is possible to detect
these faults by using a very sensitive ground-fault protection. It is applicable for networks
where normal unbalance current level is low enough to allow for sensitive setting of
50SEF.
The function also contains a blocking functionality. It is possible to block function outputs.
4.1.5.4
Operation principle
Same as 51N as described in 4.1.4.4 above.
4.1.5.5
Measurement modes
Same as 51N as described in 4.1.4.5 above.
4.1.5.6
Timer characteristics
Same as 51N as described in 4.1.4.6 above.
4.1.5.7
Application
Electric power lines experience faults for many reasons. In most cases, electrical faults
manifest in mechanical damage, which must be repaired before returning the line to
service.
Most of these faults are ground faults. A small percentage of the ground faults have a very
large impedance. They are comparable to load impedance and consequently have very
little fault current. These high impedance faults do not pose imminent danger to power
system equipment. However, they are a considerable threat to people and property. If the
natural unbalance in the system is low, the sensitive ground-fault protection can be used
to detect the ground fault.
4.1.5.8
Signals
Same as 51N as described in 4.1.4.8 above.
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Non-directional sensitive ground-fault
protection
EFLPTOC
I
0
>
50SEF
Содержание 615 Series ANSI
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