129
Secondary system supervision Chapter 11
Verifying settings by secondary
injection
(Equation 1)
4. Compare the result with the set value (consider that the set value
3U2> is in percentage of the base voltage U1b) of the negative-se-
quence operating voltage.
10.2.3 Measuring the operate value for the zero sequence function
Measure the operate value for the zero sequence function, if included in the IED.
Procedure
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 ze-
ro-sequence voltage according to the equation.
Observe that the voltages in the equation are phasors.
(Equation 2)
4. Compare the result with the set value (consider that the set value
3U0> is in percentage of the base voltage U1b) of the zero-sequence
operating voltage.
Where:
= the measured phase voltages
3U
2
⋅ U
L1
a
2
U
L2
a+⋅ U
L3
⋅+=
U
L1
U
L2
and U
L3
a1e
j
2 π⋅
3
--- - --- ----
⋅ 05 j
3
2
-------
+,–==
Where:
= the measured phase voltages.
3U
0
⋅ U
L1
U
L2
U
L3
++=
U
L1
, U
L2
and U
L3
To Next Page
Loading...
