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”.
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.