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Section 12
Testing functionality by secondary injection
12.9.2.2
198
•
Signal 3PH after about 25ms
•
Signal BLKU after about 50ms
•
Signal BLKZ after about 200ms
Measuring the operate value for the negative sequence function
Measure the operate value for the negative sequence function, if included in the IED.
1.
Simulate normal operating conditions with the three-phase currents in phase
with their corresponding phase voltages and with all of them equal to their rated
values.
2.
Slowly decrease the measured voltage in one phase until the BLKU signal
appears.
3.
Record the measured voltage and calculate the corresponding negative-
sequence voltage according to the equation.
Observe that the voltages in the equation are phasors.
3
⋅
U
=
U
+
a
2
⋅
2
L
1
EQUATION707 V2 EN
Where:
U
, U
and U
L1
L2
L3
IEC00000275 V1 EN
p ×
2
j
= ×
= -
a
1
e
0, 5
3
IECEQUATION00022 V2 EN
4.
Compare the result with the set value (consider that the set value 3U2> is in
percentage of the base voltage UBase) of the negative-sequence operating
voltage.
5.
Repeat steps
1
and 2. Then slowly increase the measured current in one phase
until the BLKU signal disappears.
6.
Record the measured current and calculate the corresponding negative-sequence
current according to the equation.
Observe that the currents in the equation are phasors.
×
=
+
2
×
3
I
I
a
I
2
L
1
L
2
IECEQUATION00021 V1 EN
Where:
,
I
I and I
L
1
L
2
L
3
IECEQUATION00020 V1 EN
U
+ ⋅
a
U
L2
L3
3
+
.
j
2
+ ×
a I
L
3
= the measured phase currents
1MRK502053-UEN B
(Equation 105)
= the measured phase voltages
(Equation 108)
Generator protection REG670 2.0 IEC
Commissioning manual
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