Three-phase fault detection
Unless it has been categorized as a single or two-phase fault, the function classifies it as
a three-phase fault if the following conditions are fulfilled:
|V
1
|
V1Level
and
|I
1
|>
I1LowLevel
or
|I
1
|>
IMaxLoad
where:
V
1
| and |I
1
|
are the positive sequence voltage and current magnitude
V1Level ,
I1LowLevel
are the setting of limits for positive sequence voltage and current
IMaxLoad
is the setting of the maximum load current
Fault evaluation and selection logic
The phase selection logic has an evaluation procedure that can be simplified according to
figure
. Only phase A is shown in the figure. If the internal signal 3 Phase fault is
activated, all four outputs PICKUP, PU_A, PU_B and PU_C gets activated.
1MRK 506 335-UUS A
Section 6
Impedance protection
157
Technical manual
Summary of Contents for REL650 series
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