Glossary of Terms

Actuator: The mechanical interface between the basic switch contacts and the means of operation, such as the operator’s finger.

Actuation Force: The required force to change a circuit’s electrical state.

Alternate (Latchin and Maintained) Action Switch: A Pushbutton style switch where the change of the electrical state is maintained between actuations.

Ampere: A unit of electrical current flow.

Base (Housing): A base of a switch is the main member to which the conducting parts or insulator unit are attached. It may also have parts of the operating or control mechanism attached.

Bounce: Rebounding of moving contact against fixed contact during transfer.

Break: Interruption of a circuit. Double-break occurs when a single mechanism interrupts two contactssimultaneously.

Capacity: Usually refers to the current handling capability of a switch.

Contact: The contact is a conducting part designed to be united by pressure to another conducting part for the purpose of carrying current.

Contact Resistance: The resistance of current flow across closed contacts.

Detent: Feature that indicates actuation point has been reached. Can also be referred to as tactile feel.

Dielectric Strength: The ability of an insulating material to resist voltage from arcing across its surface.

Dust-Tight: Sealed switch will withstand sand and dust contamination.

Electrical Life: Expected cycle life when switch is operated at full rated load.

Insulation Resistance: The resistance to current flow of the insulating materials between contacts.

Momentary Action Switch: The term given to a switch where a circuit is continuously closed or opened only when force is applied. The electrical state returns to its normal position when the force is removed.

Normally Closed: The term given to a switch where a circuit is closed in the normal switch position.

Normally Open: The term given to a switch where a circuit is open in the normal switch position.

Operating Point: Point at which contacts transfer. Usually measured from the switch mounting holes.

Over Travel: The distance an actuator travels after the circuit is closed.

Pole: The term to denote a completely separate circuit, which passes through a switch at one time.

Pre Travel: The movement of the actuator prior to closing the circuit. Sometimes identical to “Travel to Make”.

Switch Abbreviations:

N.C.: Normally Closed

N.O.: Normally Open

SPST: Single Pole Single Throw 1NO1NC

SPDT: Single Pole Double Throw 1NO2NC

DPST: Double Pole Single Throw 2NO1NC

DPDT: Double Pole Double Throw 2NO2NC

Travel to Make: The distance parallel to the designated direction of the actuator movement at which point a circuit is closed.

Watertight: Sealed switch will withstand submersion to various depths depending on specification level.

Wiping Action: Lateral travel of movable contact over fixed contact while pressure between the two contacts exists. Occurs during plunger travel. This action helps clean the contacts of contamination.

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