Undercurrent Protection For Capacitor Bank - Hitachi Relion 670 Series Applications Manual

Section 11
Multipurpose protection
0.8
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
ANSI05000535 V1 EN-US
Figure 77:
11.1.4.7

Undercurrent protection for capacitor bank

Following example explains how an undercurrent protection within CVGAPC function can be used for the
disconnection of shunt capacitor bank (SCB) in case of very low voltages at the busbar.
This functionality can be achieved by using one CVGAPC function and following shall be done to ensure
proper operation of the function:
1. Connect three-phase terminal currents to CVGAPC function and no need of voltage input, that is,
connect GRP_OFF from FXDSIGN to U3P of CVGAPC.
2. Set operation = On, select CurrentInput = MaxPh and set VoltageInput to default value
3. Set Operation_UC1 = On
4. Set EnBlkLowl_UC1 = On
5. Set BlkLowCurr_UC1 = 10.0 %IB
6. Set StartCurr_UC1 = 70.0 %IB
7. Set tDef_UC1 = 5.00 s
8. Set tResetDef_UC1 = 0.0 s
9. Set HarmRestr_UC1 = Off
182
Q [pu]
A
B
0.8 1
0.2 0.4 0.6
-rca
C
ILowSet
D
Operating Region
Loss of excitation
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Operating region
ILowSet
P [pu]
1.2 1.4
1MRK511407-UUS Rev. N
I
PS
rca
V
PS
en05000535_ansi.vsd
GUID-1AAD3844-6FEE-4050-8260-27E7A30F6352 v1
Phasor measurement unit RES670
Application manual