Overview
Any internal fault in the capacitor bank leads to unbalance in the shunt capacitor banks (SCB) and severe damage to the entire bank, which can result in an explosion or fire. In the shunt capacitor bank, the internal faults are due to open-circuit or short circuit of the capacitor units or elements. The “Phase voltage differential based capacitor bank unbalanced protection” can detect the voltage unbalance in the capacitor bank. It can be applied to grounded and ungrounded capacitor bank configurations, where the three-phase bus and tap voltage measurements are available.
For more detailed information on “Phase voltage differential based capacitor bank unbalanced protection” function, refer to ABB, Relion 670 Series manuals.
To see other supported functions, click here.
Function Identification
| Function description | IEC 61850 identification |
IEC 60617 identification |
ANSI/IEEE C37.2 device number |
| Phase voltage differential based capacitor bank unbalanced protection | SCPDPTOV | Ud > | 87V |
Signals & Setting Parameters
SCPDPTOV function block
SCPDPTOV Input signals
| SCPDPTOV Input signals | |||
| Name | Type | Default | Description |
| U3P | GROUP SIGNAL | – | Group signal for three phase bus voltage |
| U3PTAP | GROUP SIGNAL | – | Group signal for three phase tap voltage |
| U3NEUT | GROUP SIGNAL | – | Group signal for capacitor bank neutral voltage |
| BLOCK | BOOLEAN | 0 | Block of function |
| BLKTR | BOOLEAN | 0 | Block of trip |
| BLKALM | BOOLEAN | 0 | Block of alarm |
| BLKWRN | BOOLEAN | 0 | Block of warning |
| INHIBIT | BOOLEAN | 0 | Inhibit the function |
| TRIGCOMP | BOOLEAN | 0 | Trigger input to store the voltage ratios into the IED memory. The stored values will be used for future compensation in the function. |
| RESETCOMP | BOOLEAN | 0 | Reset the stored voltage ratios to set voltage ratio value |
SCPDPTOV Output signals
| SCPDPTOV Output signals | |||
| Name | Type | Description | |
| TRIP | BOOLEAN | General trip signal | |
| TRL1 | BOOLEAN | Trip signal from phase L1 | |
| TRL2 | BOOLEAN | Trip signal from phase L2 | |
| TRL3 | BOOLEAN | Trip signal from phase L3 | |
| START | BOOLEAN | General start signal | |
| STL1 | BOOLEAN | Start signal from phase L1 | |
| STL2 | BOOLEAN | Start signal from phase L2 | |
| STL3 | BOOLEAN | Start signal from phase L3 | |
| ALARM | BOOLEAN | General alarm signal | |
| ALML1 | BOOLEAN | Alarm signal from phase L1 | |
| ALML2 | BOOLEAN | Alarm signal from phase L2 | |
| ALML3 | BOOLEAN | Alarm signal from phase L3 | |
| WARNING | BOOLEAN | General warning signal | |
| WRNL1 | BOOLEAN | Warning signal from phase L1 | |
| WRNL2 | BOOLEAN | Warning signal from phase L2 | |
| WRNL3 | BOOLEAN | Warning signal from phase L3 | |
| BLKDL1 | BOOLEAN | Function operation blocked due to bus voltage in phase L1 or all three phase equivalent tap voltages going below UMin> | |
| BLKDL2 | BOOLEAN | Function operation blocked due to bus voltage in phase L2 or all three phase equivalent tap voltages going below UMin> | |
| BLKDL3 | BOOLEAN | Function operation blocked due to bus voltage in phase L3 or all three phase equivalent tap voltages going below UMin> | |
| DIFURATL1 | BOOLEAN | Alarm when deviation between the calculated and the set voltage ratio for phase L1 is larger than the set threshold limit for percentage variation (URatioVar>) | |
| DIFURATL2 | BOOLEAN | Alarm when deviation between the calculated and the set voltage ratio for phase L2 is larger than the set threshold limit for percentage variation (URatioVar>) | |
| DIFURATL3 | BOOLEAN | Alarm when deviation between the calculated and the set voltage ratio for phase L3 is larger than the set threshold limit for percentage variation (URatioVar>) | |
| COMPEXED | BOOLEAN | Indicates that a trigger was made for compensation | |
| PUDIFL1 | REAL | Differential voltage magnitude of phase L1 in % of UBase | |
| PUDIFL2 | REAL | Differential voltage magnitude of phase L2 in % of UBase | |
| PUDIFL3 | REAL | Differential voltage magnitude of phase L3 in % of UBase | |
| USEDURATL1 | REAL | Magnitude of ratio between tap and bus voltages stored and used for calculation of differential voltage of phase L1 | |
| USEDURATL2 | REAL | Magnitude of ratio between tap and bus voltages stored and used for calculation of differential voltage of phase L2 | |
| USEDURATL3 | REAL | Magnitude of ratio between tap and bus voltages stored and used for calculation of differential voltage of phase L3 | |
| URATIOL1 | REAL | Magnitude of ratio between tap and bus voltages of phase L1 | |
| URATIOL2 | REAL | Magnitude of ratio between tap and bus voltages of phase L2 | |
| URATIOL3 | REAL | Magnitude of ratio between tap and bus voltages of phase L3 | |
SCPDPTOV Non group settings (basic)
| SCPDPTOV Non group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| SCBGndType | Grounded Ungrounded |
– | – | Grounded | Selection of shunt capacitor bank ground type |
| NeutVoltMeas | Not available Available |
– | – | Available | Selection of shunt capacitor bank neutral voltage VT availability |
| GlobalBaseSel | 1 – 12 | – | 1 | 1 | Selection of one of the Global Base Value groups |
| VoltRatioL1 | 0.010 – 0.950 | – | 0.001 | 0.500 | Voltage ratio of tap voltage to bus voltage for phase L1 |
| VoltRatioL2 | 0.010 – 0.950 | – | 0.001 | 0.500 | Voltage ratio of tap voltage to bus voltage for phase L2 |
| VoltRatioL3 | 0.010 – 0.950 | – | 0.001 | 0.500 | Voltage ratio of tap voltage to bus voltage for phase L3 |
SCPDPTOV Group settings (basic)
| SCPDPTOV Group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| Operation | Off On |
– | – | Off | Operation Off / On |
| URatioVar> | 5 – 300 | % | 1 | 10 | Threshold limit for percentage variation of calculated voltage ratio from set voltage ratios (VoltRatioLx, where Lx is phase L1, L2 and L3) |
| UMin> | 5.0 – 100.0 | %UB | 0.1 | 50.0 | Minimum bus voltage for operation
in % of UBase |
| UdifWrn> | 1.0 – 95.0 | %UB | 0.1 | 5.0 | Phase voltage differential warning level in % of UBase |
| tDefWrn | 0.00 – 60.00 | s | 0.01 | 5.00 | Definite time delay to warning |
| UdifAlm> | 1.0 – 95.0 | %UB | 0.1 | 8.0 | Phase voltage differential alarm level in % of UBase |
| tDefAlm | 0.00 – 60.00 | s | 0.01 | 5.00 | Definite time delay to alarm |
| Udif> | 1.0 – 95.0 | %UB | 0.1 | 10.0 | Phase voltage differential trip level
in % of UBase |
| CurveType | Definite time Programmable |
– | – | Definite time | Selection of time delay curve type for trip |
| tDefTrip | 0.00 – 60.00 | s | 0.01 | 5.00 | Definite time delay for trip |
| k | 0.05 – 1.10 | – | 0.01 | 0.05 | Time multiplier for programmable curve for trip |
| tMin | 0.00 – 60.00 | s | 0.01 | 0.10 | Minimum operate time for programmable curve for trip |
| tReset | 0.00 – 60.00 | s | 0.01 | 0.02 | Reset time delay for warning, alarm and trip |
| tPCrv | 0.000 – 3.000 | – | 0.001 | 1.000 | Parameter P for programmble curve for trip |
| tACrv | 0.005 – 200.000 | – | 0.001 | 1.000 | Parameter A for programmble curve for trip |
| tBCrv | 0.50 – 100.00 | – | 0.01 | 1.00 | Parameter B for programmble curve for trip |
| tCCrv | 0.0 – 1.0 | – | 0.1 | 0.0 | Parameter C for programmble curve for trip |
| tDCrv | 0.000 – 60.000 | – | 0.001 | 0.000 | Parameter D for programmble curve for trip |
| CrvSat | 0 – 100 | – | 1 | 0 | Tuning parameter for programmable curve |
SCPDPTOV Non group settings (advanced)
| SCPDPTOV Non group settings (advanced) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| BlockTrip | Trip disabled Trip enabled |
– | – | Trip enabled | Trip blocked / enabled |
SCPDPTOV Monitored data
| SCPDPTOV Monitored data | ||||
| Name | Type | Values (Range) | Unit | Description |
| LASTCOMP | GROUP SIGNAL | – | – | Indicates date and time when the last trigger was made for compensation |
| UDIFL1 | REAL | – | kV | Magnitude of differential voltage of phase L1 |
| UDIFL2 | REAL | – | kV | Magnitude of differential voltage of phase L2 |
| UDIFL3 | REAL | – | kV | Magnitude of differential voltage of phase L3 |
| PUDIFL1 | REAL | – | % | Differential voltage magnitude of phase L1 in % of UBase |
| PUDIFL2 | REAL | – | % | Differential voltage magnitude of phase L2 in % of UBase |
| PUDIFL3 | REAL | – | % | Differential voltage magnitude of phase L3 in % of UBase |
| UL1 | REAL | – | kV | Bus voltage of phase L1 |
| UL2 | REAL | – | kV | Bus voltage of phase L2 |
| UL3 | REAL | – | kV | Bus voltage of phase L3 |
| UTAPL1 | REAL | – | kV | Tap voltage of phase L1 |
| UTAPL2 | REAL | – | kV | Tap voltage of phase L2 |
| UTAPL3 | REAL | – | kV | Tap voltage of phase L3 |
| UNSCB | REAL | – | kV | Measured voltage at capacitor bank neutral |
| USEDURATL1 | REAL | – | – | Magnitude of ratio between tap and bus voltage used for calculation of differential voltage of phase L1 |
| USEDURATL2 | REAL | – | – | Magnitude of ratio between tap and bus voltage used for calculation of differential voltage of phase L2 |
| USEDURATL3 | REAL | – | – | Magnitude of ratio between tap and bus voltage used for calculation of differential voltage of phase L3 |
| URATIOL1 | REAL | – | – | Magnitude of ratio between tap and bus voltage of phase L1 |
| URATIOL2 | REAL | – | – | Magnitude of ratio between tap and bus voltage of phase L2 |
| URATIOL3 | REAL | – | – | Magnitude of ratio between tap and bus voltage of phase L3 |
Logics & highlights
Single line diagram of the typical single WYE shunt capacitor bank configuration
Differential voltage calculation
Voltage ratio calculation
Grounded single WYE connected SCB
Calculation for grounded capacitor bank
Ungrounded single WYE connected SCB
Calculation for ungrounded capacitor bank
Programmable curve
Simplified Warning, Alarm, and Trip logic
INHIBIT and BLOCK behavior in the function
Cyclic reporting of calculated and stored voltage ratios over IEC 61850
Differential voltage reporting over IEC 61850
