5. Repeat steps 1 and 2. Then slowly increase the measured current in one phase until the BLKV
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
2
3
A B C
I I a I a I× = + × + ×
ANSIEQUATION00021 V1 EN-US (Equation 119)
Where:
ANSIEQUATION00020 V1 EN-US
are the measured phase currents
2
3
3
1 0, 5
2
j
a e j
p
×
= × = - +
IECEQUATION00022 V2 EN-US
7. Compare the result with the set value of the negative-sequence operating current. Consider that
the set value 3I2< is in percentage of the base current IBase.
11.10.2.3 Measuring the trip value for the zero-sequence function
M1405-72 v11
Measure the trip value for the zero-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 BLKV signal appears.
3. Record the measured voltage and calculate the corresponding zero-sequence voltage according to
the equation (observe that the voltages in the equation are phasors):
EQUATION1819-ANSI V1 EN-US (Equation 120)
Where:
EQUATION1820-ANSI V1 EN-US
are the measured phase voltages
4. Compare the result with the set value of the zero-sequence tripping voltage (consider that the set
value 3V0Pickup is in percentage of the base voltage.)
5. Repeat steps
1 and 2. Then slowly increase the measured current in one phase until the BLKV
signal disappears.
6. Record the measured current and calculate the corresponding zero-sequence current according to
the equation (observe that the currents in the equation are phasors):
ANSIEQUATION00019 V1 EN-US
(Equation 121)
Where:
Section 11 1MRK 504 165-UUS Rev. J
Testing functionality by secondary injection
236 Transformer protection RET670
Commissioning manual
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