Engee documentation

Fault (Three-Phase)

Short-circuit (short-circuit): single-, two- or three-phase as well as earth fault.

fault (three phase)

Description

The Fault (Three-Phase) block simulates any combination of single-, two- or three-phase fault and earth fault. The block specifies the start time and duration of the fault.

The unit can model the following combinations:

  • Single-phase earth fault ( - , - or - ).

  • Two-phase fault ( - , - or - ).

  • Two-phase earth fault ( - - , - - or - - ).

  • Three-phase earth fault ( - - ).

  • Three-phase earth fault ( - - - ).

The figure below shows the equivalent circuit diagram of the unit.

fault three phase 1

To determine the resistance in the equivalent circuit, use the appropriate equations from the table below.

* Short-circuit mode* Value Value Value Value

No / inactive

Infinity / open circuit

Single-phase (to earth)

-

-

-

Biphasic

-

Infinity/open circuit

-

Infinity/open circuit

-

Infinity/open circuit

Two-phase to earth

- -

- -

- -

Three-phase

- -

Infinity/open circuit

Three-phase to earth

- - -

In the table:

  • - resistance between -phase and neutral point of star connection.

  • - Resistance between -phase and neutral star point.

  • - Resistance between -phase and neutral star point.

  • - resistance between the star neutral point and the electrical earth.

  • - the value of the Faulted phase-neutral resistance parameter.

  • - value of Faulted neutral-ground resistance.

  • - value of the Unfaulted phase-neutral conductance parameter.

Ports

Non-directional

~ - three-phase port
electricity

Three-phase electrical port for connecting the unit to a circuit.

Parameters

Main

Failure mode - short-circuit type
None (by default) | a-g | b-g | c-g | a-b | b-c | c-a | a-b-g | b-c-g | c-a-g | a-b-c | a-b-c | a-b-c-g

The type of short circuit to be modelled. The following options are available:

  • None - There is no short circuit.

  • a-g

  • `b-g

  • `c-g

  • `a-b

  • `b-c

  • `c-a

  • `a-b-g

  • b-c-g

  • `c-a-g

  • `a-b-c

  • `a-b-c-g

Faulted neutral-ground resistance - neutral-to-ground resistance in short-circuit faults
1e-3 ohms (by default)

Resistance between neutral point and earth in case of active short-circuit.

Faulted phase-neutral resistance - resistance of the phase-neutral circuit during a short circuit
`1e-3 ohms (by default)

Resistance between phase and neutral point at active short-circuit.

Unfaulted phase-neutral conductance - conductance of the phase-neutral circuit in normal mode
1e-6 1/ohm (by default)

Conductance between phase and neutral point when there is no fault on that phase.

Zero-Crossing - selection of the substitution scheme
Off (by default) | On

Select this check box to use the substitution scheme as three single-phase Circuit Breaker circuit breakers that can be individually switched on and off for programming phase-to-phase faults, earth faults or a combination of phase-to-phase and earth faults. The arc extinguishing process of the Fault (Three-Phase) unit is the same as for the Circuit Breaker unit.

fault (three phase) 1 2

Temporal Trigger

Enable temporal fault trigger - time fault activation
off (by default) | on

Modelling of time faults:

  • disabled - do not simulate time faults.

  • on - simulate short-circuit faults by time. The related parameters will only be active if you select this parameter.

Fault start time - fault start time
`1.0 s (By default)

Simulation time at which moment the unit enters the fault state.

Fault duration - short-circuit duration
0.1 s (by default).

Short circuit duration. The unit exits the fault state after this time has elapsed.

Parasitics

Unfaulted phase-neutral conductance - undisturbed phase-neutral conductance
1e-6 1/Ohm (By default)

Conductance between phase connections and neutral point when the phase is not involved in a fault.

Examples