Phase Overcurrent Protection; Phase Overcurrent Protection Implementation - GE MiCOM P40 Agile Technical Manual

Chapter 6 - Current Protection Functions
3

PHASE OVERCURRENT PROTECTION

Phase current faults are faults where fault current flows between two or more phases of a power system. The fault
current may be between the phase conductors only or, between two or more phase conductors and earth.
Although not as common as earth faults (single phase to earth), phase faults are typically more severe.
3.1

PHASE OVERCURRENT PROTECTION IMPLEMENTATION

Phase Overcurrent Protection is configured in the OVERCURRENT column of the relevant settings group.
The product provides six stages of segregated three-phase overcurrent protection, each with independent time
delay characteristics. The settings are independent for each stage, but for each stage, the settings apply to all
phases.
Stages 1, 2 and 5 provide a choice of operate and reset characteristics, where you can select between:
A range of IDMT (Inverse Definite Minimum Time) curves based on IEC and IEEE standards
●
A range of programmable user-defined curves
●
● DT (Definite Time) characteristic
For stage 1, this is achieved using the following settings:
I>1 Function for the overcurrent operate characteristic
●
I>1 Reset Char for the overcurrent reset characteristic
●
I>1 Usr Rst Char for the reset characteristic for user-defined curves
●
The setting names for other stages follow the same principles.
The IDMT-equipped stages, (1,2 and 5) also provide a Timer Hold facility. Stage 1 for example, is configured using
the cells I>1 tReset. This setting does not apply to IEEE curves.
Stages 3, 4 and 6 have definite time characteristics only.
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