# DPST Switch

Double-pole single-throw switch

**Libraries:**

Simscape /
Electrical /
Switches & Breakers

## Description

The DPST Switch block models a double-pole single-throw switch.

When the switch is closed, ports **p1**
and **p2** are connected to ports **n1**
and **n2**, respectively.

Closed connections are modeled by a resistor with value equal to the
**Closed resistance** parameter value. Open
connections are modeled by a resistor with value equal to the reciprocal of
the **Open conductance** parameter value.

If the **Threshold width** parameter is set to zero, the
switch is closed if the voltage presented at the **vT**
control port exceeds the value of the **Threshold**
parameter.

If the **Threshold width** parameter is greater
than zero, then switch conductance *G* varies smoothly
between off-state and on-state values:

$$G=\frac{x}{{R}_{closed}}+\left(1-x\right){G}_{open}$$

$$\lambda =\frac{vT-\text{Threshold}}{\text{Thresholdwidth}}$$

$$x=\{\begin{array}{ll}0\hfill & \text{for}\lambda \le 0\hfill \\ 3{\lambda}^{2}-2{\lambda}^{3}\hfill & \text{for}0\lambda 1\hfill \\ 1\hfill & \text{for}\lambda \ge 1\hfill \end{array}$$

The block uses the function 3*λ*^{2} –
2*λ*^{3} because its
derivative is zero for *λ* =
0 and *λ* =
1.

Defining a small positive **Threshold width** can help solver convergence in
some models, particularly if the control port signal *vT* varies
continuously as a function of other network variables. However, defining a nonzero threshold
width precludes the solver making use of switched linear optimizations. Therefore, if the
rest of your network is switched linear, set **Threshold width** to
zero.

Optionally, you can add a delay between the point at which the voltage at
**vT** passes the threshold and the switch opening
or closing. To enable the delay, on the **Dynamics** tab,
set the **Model dynamics** parameter to ```
Model
turn-on and turn-off times
```

.

## Ports

Refer to the figure for port locations.

### Input

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2012b**