Overview
The “Restricted ground fault protection” function detects ground faults in transformers, shunt reactors, neutral reactors or rotating machinery in which the neutral point is grounded. It has high sensitivity to ground faults near the neutral point and is supplemental main protection to longitudinal differential protection.
For more detailed information on “Restricted ground fault protection” function, refer to SIPROTEC 5 devices, V8.30 & higher manuals.
To see other supported functions, click here.
Structure/Embedding of the Function
Setting Parameters
Setting parameters for Restricted Ground-Fault Protection
| Addr. | Parameter | C | Setting Options | Default Setting |
| 87N REF # | ||||
| _:1 | 87N REF #:Mode | off on test |
off | |
| _:2 | 87N REF #:Operate & flt.rec. blocked | no yes |
no | |
| _:103 | 87N REF #:Threshold | 0.05 I/IrObj to 2.00 I/IrObj | 0.20 I/IrObj | |
| _:105 | 87N REF #:Slope | 0.00 to 0.95 | 0.07 | |
| _:109 | 87N REF #:Operate delay | 0.00 s to 60.00 s; ∞ | 0.00 s | |
| _:191 | 87N REF #:Reference side is | not assigned Side 1 Side 2 Side 3 Side 4 Side 5 |
not assigned | |
| _:151 | 87N REF #:MU-ID Side 1 Mp3ph 1 |
0 to 100 | 0 | |
| _:152 | 87N REF #:MU-ID Side 1 Mp3ph 2 |
0 to 100 | 0 | |
| _:153 | 87N REF #:MU-ID Side 1 Mp3ph 3 |
0 to 100 | 0 | |
| _:154 | 87N REF #:MU-ID Side 1 Mp3ph 4 |
0 to 100 | 0 | |
| _:156 | 87N REF #:MU-ID Side 2 Mp3ph 1 |
0 to 100 | 0 | |
| _:157 | 87N REF #:MU-ID Side 2 Mp3ph 2 |
0 to 100 | 0 | |
| _:158 | 87N REF #:MU-ID Side 2 Mp3ph 3 |
0 to 100 | 0 | |
| _:159 | 87N REF #:MU-ID Side 2 Mp3ph 4 |
0 to 100 | 0 | |
| _:161 | 87N REF #:MU-ID Side 3 Mp3ph 1 |
0 to 100 | 0 | |
| _:162 | 87N REF #:MU-ID Side 3 Mp3ph 2 |
0 to 100 | 0 | |
| _:163 | 87N REF #:MU-ID Side 3 Mp3ph 3 |
0 to 100 | 0 | |
| _:164 | 87N REF #:MU-ID Side 3 Mp3ph 4 |
0 to 100 | 0 | |
| _:166 | 87N REF #:MU-ID Side 4 Mp3ph 1 |
0 to 100 | 0 | |
| _:167 | 87N REF #:MU-ID Side 4 Mp3ph 2 |
0 to 100 | 0 | |
| _:168 | 87N REF #:MU-ID Side 4 Mp3ph 3 |
0 to 100 | 0 | |
| _:169 | 87N REF #:MU-ID Side 4 Mp3ph 4 |
0 to 100 | 0 | |
| _:171 | 87N REF #:MU-ID Side 5 Mp3ph 1 |
0 to 100 | 0 | |
| _:172 | 87N REF #:MU-ID Side 5 Mp3ph 2 |
0 to 100 | 0 | |
| _:173 | 87N REF #:MU-ID Side 5 Mp3ph 3 |
0 to 100 | 0 | |
| _:174 | 87N REF #:MU-ID Side 5 Mp3ph 4 |
0 to 100 | 0 | |
| _:185 | 87N REF #:MU-ID Mp1ph | 0 to 100 | 0 | |
Logic Diagrams & highlights
Logic Diagram of the Restricted Ground-Fault Protection Function
Basic Principle of the Function
Calculation of currents
Stabilized Characteristic Curve
Operate Curve Depending on the Phase Angle
Angle Decision in Internal and External Faults
Ratio IY* to 3I0*
Behavior under Different Fault Conditions
Connecting a Ground Side on the Auto Transformer
Calculation of the neutral-point current
Application Star Side
Function Group Structure of the Restricted Ground-Fault Protection
Current-Transformer Connection (1) According to Definition
Current-Transformer Connection (2) According to Definition
Current-Transformer Connection on the Transformer
Principal Fault Current Curves with a 1-Pole Ground Fault
Derivation of the Setting Value for the Gradient
Activation and Application Example of an Auto Transformer (500 MVA: 400 kV, 230 kV; 125 MVA: 34.5 kV)
Application with Resistance-Grounded Neutral Point
Application with Neutral Reactor
Application with Neutral Reactor
