# Documentation

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# Time-Based Fault

Time-based single-phase, two-phase, or three-phase grounded or ungrounded fault

## Library

Passive Devices / Faults

## Description

The Time-Based Fault block models any permutation of a single-phase, two-phase, or three-phase grounded or ungrounded fault. You specify the fault activation time using the block Fault start time parameter. The fault becomes inactive when the fault duration that you specify elapses.

You can set the Time-Based Fault block to represent any of 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 Time-Based Fault block.

You can determine the resistance in the equivalent circuit using the equations in the table.

Fault typeValue of RaValue of RbValue of RcValue of Rg

None / inactive

$\frac{1}{{G}_{pn}}$$\frac{1}{{G}_{pn}}$$\frac{1}{{G}_{pn}}$

Infinity / open circuit

a-g

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

b-g

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

c-g

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

a-b

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

Infinity / open circuit

b-c

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

Infinity / open circuit

c-a

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

Infinity / open circuit

a-b-g

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

b-c-g

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

c-a-g

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

a-b-c

${R}_{pn}$${R}_{pn}$${R}_{pn}$

Infinity / open circuit

a-b-c-g

${R}_{pn}$${R}_{pn}$${R}_{pn}$${R}_{ng}$

where:

• Ra is the resistance between the a-phase and the neutral point of a wye connection.

• Rb is the resistance between the b-phase and the neutral point of a wye connection.

• Rc is the resistance between the c-phase and the neutral point of a wye connection.

• Rg is the resistance between the neutral point of a wye connection and electrical reference.

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

• Rng is the value of the Faulted neutral-ground resistance parameter.

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

## Parameters

### Main Tab

Fault type

Select one of the following:

• None — Specifies that the fault is not active. This is the default value.

• Single-phase to ground (a-g)

• Single-phase to ground (b-g)

• Single-phase to ground (c-g)

• Two-phase (a-b)

• Two-phase (b-c)

• Two-phase (c-a)

• Two-phase to ground (a-b-g)

• Two-phase to ground (b-c-g)

• Two-phase to ground (c-a-g)

• Three-phase (a-b-c)

• Three-phase to ground (a-b-c-g)

Faulted phase-neutral resistance

Resistance between the phase connection and the neutral point when the fault is active. This parameter is visible if the Fault type parameter is set to anything other than None. The default value is 1e-3 Ohm.

Faulted neutral-ground resistance

Resistance between the neutral point and the electrical reference when fault is active. This parameter is visible if the Fault type parameter is set to any fault which includes a ground connection. The default value is 1e-3 Ohm.

Fault start time

Simulation time when the fault becomes active. This parameter is visible if the Fault type parameter is set to anything other than None. The default value is 1 s.

Fault duration

Period of time that the fault is active. This parameter is visible if the Fault type parameter is set to anything other than None. The default value is 0.1 s.

### Parasitics Tab

Unfaulted phase-neutral conductance

Conductance between the phase connections and the neutral point when a phase is not involved in the fault. The default value is 1e-6 1/Ohm.

## Ports

The block has one expandable three-phase port for connecting the fault to the system.