Snap Action Switches Information
Snap action switches are mechanical switches that produce a very rapid transfer of contacts from one position to another. They are useful in situations that require a fast opening or closing of a circuit, such as a mouse button or appliance setting.
Lever actuators can be straight or formed levers.
A pushbutton actuator is sometimes called plunger style.
A roller style actuator can be actual roller or simulated roller.
Pole and Throw Configurations
Single Pole Single Throw (SPST)
SPST is a switch that makes or breaks the connection of a single conductor in a single branch circuit. This switch typically has two terminals. It is commonly referred to as a "Single-Pole" Switch.
Single Pole Double Throw (SPDT)
SPDT is a switch that makes or breaks the connection of a single conductor with either of two other single conductors. This switch typically has 3 terminals, and is commonly used in pairs and called a "Three-Way" switch.
Double Pole Single Throw (DPST)
DPST is a switch that makes or breaks the connection of two circuit conductors in a single branch circuit. This switch typically has four terminals.
Double Pole Double Throw (DPDT)
DPDT is a switch that makes or breaks the connection of two conductors to two separate circuits. This switch typically has six terminals and is available in both momentary and maintained contact versions. A normally open (NO) switch has contacts that are open or disconnected in their unactuated (normal) position. A normally closed (NC) switch has contacts that are closed or connected in their unactuated (normal) position.
Electrical Switch Specifications
The maximum current rating is the maximum nominal, or nameplate current capacity of a device.
The maximum AC voltage rating is the maximum AC voltage capacity of a device.
The maximum DC voltage rating is the maximum DC voltage capacity of a device.
Mechanical Switch Specifications
The actuating force is the force required to actuate switch.
The maximum operating frequency is the "fastest" rate the switch can be operated at.
The total travel is the total movement of switch without damage occurring (Operating Travel + Pre-travel).
Pre-travel is the distance if button (actuator) movement from rest position to the point of operation. Pre-travel is often specified as a maximum.
The operating temperature is the temperature range over which the device must operate.
Many switch manufacturers use common terminology to describe standard sizes available for switches. These standard terms are:
Materials of Construction
MIL-DTL-15291 - Switches, rotary, snap action, and detent/spring return action, general specifications