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Signal-enabled or time-based, single-phase, two-phase, or three-phase, grounded or ungrounded fault

**Library:**Simscape / Electrical / Utilities

The Fault (Three-Phase) models any permutation of a single-phase, two-phase, or three-phase grounded or ungrounded fault. The block can impose both time- and event-based faults. The block can impose one or both type of faults, consecutively, at the same time, or for an overlapping time period.

For a time-based or temporal fault, specify the fault activation time using the block
**Fault start time** parameter. The fault becomes inactive when the
fault duration that you specify elapses.

For an event-based fault, specify the fault activation threshold using the block
**Threshold** parameter. An external control signal
*F* enables the fault. The fault is active when
*F* is greater than the threshold. The fault is inactive when
*F* is less than or equal to the threshold.

The block can represent these permutations:

Single-phase-to-ground fault (

*a*-*g*,*b*-*g*, or*c*-*g*)Two-phase fault (

*a*-*b*,*b*-*c*, or*c*-*a*)Two-phase-to-ground fault (

*a*-*b*-*g*,*b*-*c*-*g*, or*c*-*a*-*g*)Three-phase fault (

*a*-*b*-*c*)Three-phase-to-ground fault (

*a*-*b*-*c*-*g*)

The figure shows the equivalent circuit diagram for the block.

To determine the resistance in the equivalent circuit, apply the relevant equations from the table.

Failure mode | Value of R
_{a}
| Value of R
_{b}
| Value of R
_{c}
| Value of R
_{g}
| |
---|---|---|---|---|---|

None / inactive | $$\frac{1}{{G}_{pn}}$$ | $$\frac{1}{{G}_{pn}}$$ | $$\frac{1}{{G}_{pn}}$$ | Infinity / open circuit | |

Single phase to ground |
| $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{ng}$$ |

| $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{ng}$$ | |

| $$\frac{1}{{G}_{pn}}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | $${R}_{ng}$$ | |

Two phase |
| $${R}_{pn}$$ | $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | Infinity / open circuit |

| $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | $${R}_{pn}$$ | Infinity / open circuit | |

| $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | Infinity / open circuit | |

Two phase to ground |
| $${R}_{pn}$$ | $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{ng}$$ |

| $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | $${R}_{pn}$$ | $${R}_{ng}$$ | |

| $${R}_{pn}$$ | $$\frac{1}{{G}_{pn}}$$ | $${R}_{pn}$$ | $${R}_{ng}$$ | |

Three phase |
| $${R}_{pn}$$ | $${R}_{pn}$$ | $${R}_{pn}$$ | Infinity / open circuit |

Three phase to ground |
| $${R}_{pn}$$ | $${R}_{pn}$$ | $${R}_{pn}$$ | $${R}_{ng}$$ |

where:

*R*is the resistance between the_{a}*a*-phase and the neutral point of a wye connection.*R*is the resistance between the_{b}*b*-phase and the neutral point of a wye connection.*R*is the resistance between the_{c}*c*-phase and the neutral point of a wye connection.*R*is the resistance between the neutral point of a wye connection and electrical reference._{g}*R*is the value of the_{pn}**Faulted phase-neutral resistance**parameter.*R*is the value of the_{ng }**Faulted neutral-ground resistance**parameter.*G*is the value of the_{pn}**Unfaulted phase-neutral conductance**parameter.