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. Actuator styles available for snap action switches include lever, pushbutton, and roller. 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 for snap action switches can be single pole single throw (SPST), single pole double throw (SPDT), double pole single throw (DPST), or double pole double throw (DPDT). 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. 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. 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. 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.
Important electrical switch specifications to consider for snap action switches include maximum current rating, maximum AC voltage rating, and maximum DC voltage rating. 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. Important mechanical switch specifications to consider for snap action switches include the actuating force, maximum operating frequency, total travel, pre-travel, and operating temperature. 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.
Other important parameters to consider in the selection of snap action switches include the size, and materials of construction. Many switch manufacturers use common terminology to describe standard sizes available for switches. These standard terms are subminiature, miniature and standard. Materials of construction for the base and actuator include thermoplastics or plastics and metals.
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