Overview
When the laminated core of a power transformer or generator is subjected to a magnetic flux density beyond its design limits, stray flux will flow into non-laminated components that are not designed to carry flux. This will cause eddy currents to flow. These eddy currents can cause excessive heating and severe damage to insulation and adjacent parts in a relatively short time. The “Overexcitation protection (OEXPVPH)” function has settable inverse operating curves and independent alarm stages.
For more detailed information on “Overexcitation protection (OEXPVPH)” 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 |
| Overexcitation protection | OEXPVPH | U/f > | 24 |
Signals & Setting Parameters
OEXPVPH function block
OEXPVPH Input signals
| OEXPVPH Input signals | |||
| Name | Type | Default | Description |
| I3P | GROUP SIGNAL | – | Current connection |
| U3P | GROUP SIGNAL | – | Voltage connection |
| BLOCK | BOOLEAN | 0 | Block of function |
| RESET | BOOLEAN | 0 | Reset operation |
OEXPVPH Output signals
| OEXPVPH Output signals | |||
| Name | Type | Description | |
| TRIP | BOOLEAN | Trip from overexcitation function | |
| START | BOOLEAN | Overexcitation above set operate level (instantaneous) | |
| ALARM | BOOLEAN | Overexcitation above set alarm level (delayed) | |
OEXPVPH Group settings (basic)
| OEXPVPH Group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| Operation | Off On |
– | – | Off | Operation Off / On |
| V/Hz> | 100.0 – 180.0 | %UB/f | 0.1 | 110.0 | Operate level of V/Hz at no load and rated freq in % of (UBase/frated) |
| V/Hz>> | 100.0 – 200.0 | %UB/f | 0.1 | 140.0 | High level of V/Hz above which tMin is used, in % of (UBase/frated) |
| XLeak | 0.000 – 200.000 | Ohm | 0.001 | 0.000 | Winding leakage reactance in primary ohms |
| TrPulse | 0.000 – 60.000 | s | 0.001 | 0.100 | Length of the pulse for trip signal (in sec) |
| tMin | 0.000 – 60.000 | s | 0.001 | 7.000 | Minimum trip delay for V/Hz inverse curve, in sec |
| tMax | 0.00 – 9000.00 | s | 0.01 | 1800.00 | Maximum trip delay for V/Hz inverse curve, in sec |
| tCooling | 0.10 – 9000.00 | s | 0.01 | 1200.00 | Transformer magnetic core cooling time constant, in sec |
| CurveType | IEEE Tailor made |
– | – | IEEE | Inverse time curve selection, IEEE/ Tailor made |
| kForIEEE | 1 – 60 | – | 1 | 1 | Time multiplier for IEEE inverse type curve |
| AlarmLevel | 50.0 – 120.0 | % | 0.1 | 100.0 | Alarm operate level as % of operate level |
| tAlarm | 0.00 – 9000.00 | s | 0.01 | 5.00 | Alarm time delay, in sec |
OEXPVPH Group settings (advanced)
| OEXPVPH Group settings (advanced) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| t1Tailor | 0.00 – 9000.00 | s | 0.01 | 7200.00 | Time delay t1 (longest) for tailor made curve, in sec |
| t2Tailor | 0.00 – 9000.00 | s | 0.01 | 3600.00 | Time delay t2 for tailor made curve, in sec |
| t3Tailor | 0.00 – 9000.00 | s | 0.01 | 1800.00 | Time delay t3 for tailor made curve, in sec |
| t4Tailor | 0.00 – 9000.00 | s | 0.01 | 900.00 | Time delay t4 for tailor made curve, in sec |
| t5Tailor | 0.00 – 9000.00 | s | 0.01 | 450.00 | Time delay t5 for tailor made curve, in sec |
| t6Tailor | 0.00 – 9000.00 | s | 0.01 | 225.00 | Time delay t6 (shortest) for tailor made curve, in sec |
OEXPVPH Non group settings (basic)
| OEXPVPH Non group settings (basic) | |||||
| Name | Values (Range) | Unit | Step | Default | Description |
| MeasuredU | PosSeq L1L2 L2L3 L3L1 | – | – | L1L2 | Selection of measured voltage |
| MeasuredI | L1L2 L2L3 L3L1 PosSeq |
– | – | L1L2 | Selection of measured current |
| GlobalBaseSel | 1 – 12 | – | 1 | 1 | Selection of one of the Global Base Value groups |
OEXPVPH Monitored data
| OEXPVPH Monitored data | ||||
| Name | Type | Values (Range) | Unit | Description |
| TMTOTRIP | REAL | – | s | Calculated time to trip for overexcitation, in sec |
| VPERHZ | REAL | – | V/Hz | Voltage to frequency ratio in per-unit |
| THERMSTA | REAL | – | % | Overexcitation thermal status in % of trip level |
Logics & highlights
Restrictions imposed on inverse delays by tMax and tMin
Delays inversely proportional to the square of the overexcitation
An example of a Tailor-Made delay characteristic
A simplified logic diagram of the Overexcitation protection OEXPVPH
