Measuring The Operate Value For The Negative Sequence Function - ABB RET670 Installation And Commissioning Manual

Section 13
Verifying settings by secondary injection
13.10.2.2
172
6. Disconnect one of the phase voltages and observe the logical output signals
on the binary outputs of the IED.. BLKU and BLKZ signals should
simultaneously appear.
BLKU and BLKZ signals should simultaneously appear.
7. After more than 5 seconds disconnect the remaining two-phase voltages and
all three currents.
• There should be no change in the high status of the output signals
BLKU and BLKZ.
• The signal 3PH will appear.
8. Establish normal voltage and current operating conditions simultaneously and
observe the corresponding output signals.
They should change to logical 0 as follows:
• 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.
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 negative-
sequence voltage according to the equation.
Observe that the voltages in the equation are phasors.
2
× ×
3 U = U + a
2 L 1
EQUATION707 V1 EN
Where:
U U
L1 L2
EQUATION708 V1 EN
2 p ×
---------- -
j
3
×
a = 1 e = –
EQUATION709 V1 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.
×
U + a U
L 2 L3
and U
L3
3
, ------ -
0 5 + j
2
1MRK 504 088-UEN C
(Equation 13)
= the measured phase voltages
Installation and commissioning manual