Overview
The “Motor differential protection” function detects ground faults and multiphase short circuits in motors, and also ground faults during the operation of motors using mains with a grounded neutral point.
For more detailed information on “Motor differential 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 Motor differential protection
| Addr. | Parameter | C | Setting Options | Default Setting |
| General | ||||
| _:2311:186 | General:Protection Mode | Transformer Current node |
Transformer | |
| _:2311:100 | General:Meas. gnd. current side 1 | no yes |
no | |
| _:2311:101 | General:Meas. gnd. current side 2 | no yes |
no | |
| _:2311:102 | General:Meas. gnd. current side 3 | no yes |
no | |
| _:2311:181 | General:Meas. gnd. curr. autosides | no with CT 1ph with CT 3ph |
no | |
| _:2311:182 | General:Meas. gnd. curr. comp.side | no yes |
no | |
| _:2311:191 | General:Reference side is | not assigned Side 1 Side 2 Side 3 |
not assigned | |
| _:2311:151 | General:MU-ID Side 1 Mp3ph 1 |
0 to 100 | 0 | |
| _:2311:152 | General:MU-ID Side 1 Mp3ph 2 |
0 to 100 | 0 | |
| _:2311:153 | General:MU-ID Side 1 Mp3ph 3 |
0 to 100 | 0 | |
| _:2311:154 | General:MU-ID Side 1 Mp3ph 4 |
0 to 100 | 0 | |
| _:2311:155 | General:MU-ID Side 1 Mp1ph | 0 to 100 | 0 | |
| _:2311:156 | General:MU-ID Side 2 Mp3ph 1 |
0 to 100 | 0 | |
| _:2311:157 | General:MU-ID Side 2 Mp3ph 2 |
0 to 100 | 0 | |
| _:2311:158 | General:MU-ID Side 2 Mp3ph 3 |
0 to 100 | 0 | |
| _:2311:159 | General:MU-ID Side 2 Mp3ph 4 |
0 to 100 | 0 | |
| _:2311:160 | General:MU-ID Side 2 Mp1ph | 0 to 100 | 0 | |
| _:2311:161 | General:MU-ID Side 3 Mp3ph 1 |
0 to 100 | 0 | |
| _:2311:162 | General:MU-ID Side 3 Mp3ph 2 |
0 to 100 | 0 | |
| _:2311:163 | General:MU-ID Side 3 Mp3ph 3 |
0 to 100 | 0 | |
| _:2311:164 | General:MU-ID Side 3 Mp3ph 4 |
0 to 100 | 0 | |
| _:2311:165 | General:MU-ID Side 3 Mp1ph | 0 to 100 | 0 | |
| _:2311:185 | General:MU-ID Mp1ph | 0 to 100 | 0 | |
| General | ||||
| _:11041:1 | I-DIFF:Mode | off on test |
off | |
| _:11041:2 | I-DIFF:Operate & flt.rec. blocked | no yes |
no | |
| _:11041:6 | I-DIFF:Operate delay | 0.00 s to 60.00 s | 0.00 s | |
| Operate curve | ||||
| _:11041:3 | I-DIFF:Threshold | 0.05 I/IrObj to 2.00 I/IrObj | 0.20 I/IrObj | |
| _:11041:100 | I-DIFF:Slope 1 | 0.00 to 0.80 | 0.30 | |
| _:11041:101 | I-DIFF:Intersection 1 Irest | 0.00 I/IrObj to 5.00 I/IrObj | 0.67 I/IrObj | |
| _:11041:102 | I-DIFF:Slope 2 | 0.25 to 0.95 | 0.70 | |
| _:11041:103 | I-DIFF:Intersection 2 Irest | 1.00 I/IrObj to 20.00 I/IrObj | 2.50 I/IrObj | |
| Starting detection | ||||
| _:11041:106 | I-DIFF:Starting detection | no yes |
yes | |
| _:11041:107 | I-DIFF:Thresh. startup detection | 0.1 I/IrObj to 2.0 I/IrObj | 0.1 I/IrObj | |
| _:11041:108 | I-DIFF:Factor increasing char. | 1.0 to 5.0 | 1.0 | |
| _:11041:109 | I-DIFF:Max. perm. Start. time | 0.1 s to 180.0 s | 5.0 s | |
| DC offset detection | ||||
| _:11041:110 | I-DIFF:Factor increasing char. DC | 1.0 to 5.0 | 2.3 | |
| Ext. fault detection | ||||
| _:11041:128 | I-DIFF:Threshold add-on stabiliz. | 1.00 I/IrObj to 20.00 I/IrObj | 2.00 I/IrObj | |
| _:11041:129 | I-DIFF:Time of add-on stabiliz. | 0.00 s to 5.00 s;∞ | 0.30 s | |
| _:11041:130 | I-DIFF:Crossblk. time add- on st. | 0.00 s to 2.00 s;∞ | 0.30 s | |
| I-DIFF fast | ||||
| _:11071:1 | I-DIFF fast:Mode | off on test |
off | |
| _:11071:3 | I-DIFF fast:Threshold | 0.5 I/IrObj to 35.0 I/IrObj | 7.5 I/IrObj | |
| _:11071:6 | I-DIFF fast:Operate delay | 0.00 s to 60.00 s | 0.00 s | |
| _:11071:100 | I-DIFF fast:Operate & flt.rec. blocked | no yes |
no | |
| I-DIFF unrestr | ||||
| _:18002:1 | I-DIFF unrestr:Mode | off on test |
off | |
| _:18002:3 | I-DIFF unrestr:Threshold | 0.5 I/IrObj to 35.0 I/IrObj | 10.0 I/IrObj | |
| _:18002:6 | I-DIFF unrestr:Operate delay | 0.00 s to 60.00 s | 0.00 s | |
| _:18002:100 | I-DIFF unrestr:Operate & flt.rec. blocked | no yes |
no | |
Logic Diagrams & highlights
Basic Principle of Differential Protection Using the Example of 2 Sides
Current Stabilization
Principle Current Course in External Short Circuit and Temporary Current-Transformer Saturation on One Side
Logic Diagram of the Differential Protection Function
Operate Curve of the Differential Protection Function
Amount Correction
Calculation of differential protection currents
Pickup Characteristic of the Differential Protection
Increasing the Characteristic Curve after DC Detection
Logic DC Detection
Logic Startup Detection
Characteristic-Curve Increase at Startup
Trip Logic of I-DIFF
Instantaneous-Value Method calculations
I-DIFF Fast Characteristic Curve
Curve Plot for Internal Fault with Transformer Saturation (k= 0.65)
Curve Plot for External Fault with Transformer Saturation (k= 0.65)
Logic of the I-DIFF Fast Differential Protection Function
Operate current calculation
I-DIFF Unrestrained Characteristic Curve
Logic of the I-DIFF Unrestrained Differential Protection Function
Overall Trip Logic
Connection Example
