ABB REG670 2.0 IEC - Measuring the Operate Value for the Negative Sequence Function

• Signal 3PH after about 25ms
• Signal BLKU after about 50ms
• Signal BLKZ after about 200ms
12.9.2.2 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
21
2
⋅+⋅+⋅UU UU
LL2L3
= aa
EQUATION707 V2 EN (Equation 105)
Where:
U
L1
, U
L2
and U
L3
IEC00000275 V1 EN
= the measured phase voltages
2
3
3
1 0,5
2
j
a e j
p ×
= × = - +
.
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
1 2 32
3
L L L
I I a I a I× = + × + ×
IECEQUATION00021 V1 EN
(Equation 108)
Where:
1 2 3L L L
I I and I ,
IECEQUATION00020 V1 EN
= the measured phase currents
Section 12 1MRK502053-UEN B
Testing functionality by secondary injection
198 Generator protection REG670 2.0 IEC
Commissioning manual