# Constant Current Load (Three-Phase)

**Libraries:**

Simscape /
Electrical /
Passive

## Description

The Constant Current Load (Three-Phase) block implements a constant current load for a three-phase supply.

This block consumes a current equal to the value of the **Consumed current
(RMS)** parameter as long as the voltage from the three-phase supply is
equal to or greater than the value specified for the **Minimum supply voltage
(phase-to-phase RMS)** parameter.

When the voltage from the three-phase supply drops below the value of
**Minimum supply voltage (phase-to-phase RMS)**, the load behaviour
changes and the block models a load with constant resistance.

### Equations

If the three-phase voltages are balanced, the phase-to-phase RMS voltage is defined by this equation:

$${V}_{lin{e}_{RMS}}=\sqrt{{\left({v}_{a}-{v}_{dc}\right)}^{2}+{\left({v}_{b}-{v}_{dc}\right)}^{2}+{\left({v}_{c}-{v}_{dc}\right)}^{2}},$$

where $${v}_{dc}=\frac{{v}_{a}+{v}_{b}+{v}_{c}}{3}.$$

The currents for each of the three phases are defined by this equation:

$${i}_{k}(t)=\frac{{v}_{k}(t)}{{R}_{equiv}},$$

where *R _{equiv}* is the
equivalent resistance and depends on value of the

**Minimum supply voltage (phase-to-phase RMS)**parameter.

If the voltage from the three-phase supply is greater than the value specified for the
**Minimum supply voltage (phase-to-phase RMS)** parameter, the
equivalent resistance is defined by:

$${R}_{equiv}=\frac{\frac{{v}_{pk}}{\sqrt{2}}}{{I}_{RM{S}_{consumed}}},$$

where *v _{pk}* is the
voltage peak magnitude and

*I*is the value of the

_{RMSconsumed}**Consumed current (RMS)**parameter.

If the voltage from the three-phase supply is less than the value specified for
the **Minimum supply voltage (phase-to-phase RMS)** parameter, the
equivalent resistance is defined by:

$${R}_{equiv}=\frac{{v}_{phRM{S}_{min}}}{{I}_{RM{S}_{consumed}}},$$

where $${v}_{phRM{S}_{min}}=\frac{{v}_{lineRM{S}_{min}}}{\sqrt{3}}$$ is the phase-to-ground RMS minimum voltage.

### Faults

To model a fault in the Constant Current Load (Three-Phase) block, in the
**Faults** section, click the **Add fault** hyperlink in
the parameter that corresponds to the specific fault that you want to model. When the
**Create Fault** window opens, you use it to specify the fault properties.
For more information about fault modeling, see Fault Behavior Modeling and Fault Triggering.

The Constant Current Load (Three-Phase) block allows you to model an electrical fault as an open circuit. The block can trigger fault events either:

At a specific time

When a power limit is exceeded for longer than a specific time interval

### Load-Flow Analysis

If the block is in a network that is compatible with frequency-time simulation mode, you can perform a load-flow analysis on the network. A load-flow analysis provides steady-state values that you can use to initialize a machine.

For more information, see Perform a Load-Flow Analysis Using Simscape Electrical and Frequency and Time Simulation Mode.

## Ports

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2021a**