Hitachi Relion 670 Series Applications Manual page 57

1MRK511407-UUS Rev. N
A
CT 800/1
Star Connected
Protected Object
ANSI06000644 V3 EN-US
Figure 14: Wye connected three-phase CT set with its wye point away from the protected object and the
residual/neutral current connected to the IED
Where:
1)
2)
3)
4)
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Phasor measurement unit RES670
Application manual
B C
I_N
I_C
I_B
I_A
Shows how to connect three individual phase currents from a wye connected three-phase CT set to the three CT
inputs of the IED.
Shows how to connect residual/neutral current from the three-phase CT set to the fourth input in the IED. It shall
be noted that if this connection is not made, the IED will still calculate this current internally by vectorial
summation of the three individual phase currents.
Is the TRM where these current inputs are located. It shall be noted that for all these current inputs the following
setting values shall be entered.
• CTprim=800A
• CTsec=1A
• CTStarPoint=FromObject
• ConnectionType=Ph-N
The ratio of the first two parameters is only used inside the IED. The third parameter as set in this example will
have no influence on measured currents (that is, currents are already measured towards the protected object).
Are three connections made in the Signal Matrix tool (SMT) and Application configuration tool (ACT), which
connects these three current inputs to the first three input channels on the preprocessing function block 6).
Depending on the type of functions, which need this current information, more than one preprocessing block
might be connected in parallel to these three CT inputs.
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IED
3
1
4
2
Analog inputs
6
SMAI2
BLOCK AI3P
REVROT AI1
^GRP2_A AI2
^GRP2_B AI3
^GRP2_C AI4
^GRP2_N AIN
5
ANSI06000644-3-en.vsdx
Section 4
51