Glossary

Clearance Distance - the distance in air between current carrying parts of opposite polarity or between any current carrying part and an earthed-(grounded) metal plate to which the switch is attached.

Creepage Distance - the path along the surface of insulating material between current carrying parts of opposite polarity or between any current carrying part and an earthed (grounded) metal plate to which the switch is attached.

Insulation Resistance - resistance as measured between the normally closed terminals, or between all terminals connected together and a metal plate to which the switch is mounted. In dry conditions the value would be expected to be greater than 5M?

Single Throw - a switch which provided an ON-OFF or OFF- ON function but does not change over from one conductor to another. Such switches are usually referred to as being «normally-closed only» or «normally-open only».

Switching Cycle - one complete switching operating from free position into overtravel and back through release position to free position.

Resistance - a total resistance offered by a switch in a circuit, as measured from terminal through mating contacts, to terminal

Transit Time - the time taken by the moving contact in a snap- action mechanism to move from one stable position to another.


Positions - forces - movements

Free position - Position of the actuator, without any influence from an external force

Operating position - Position of the actuator when contact changeover takes place

Total travel position - Position of the actuator at the end of the allowed travel

Release position - The force required to move the actuator from the free position to the operating position

Actuating force - Difference between actuating force and release force

Force differential - Movement of the switch actuator between free and operating position

Pre-travel - Movement of the switch actuator beyond the operating position

Total travel - Distance between operating position and release position

Movement differential - Release travel Movement of the switch actuator between release and total travel position

Post release travel - Movement of the switch actuator between release and free position


Switch Life

Electrical Life - the electrical life data contained in this catalog is based on laboratory controlled tests. In practice, frequency and speed of operation, type of load, suppression,actuator travel used, ambient humidity and temperature and other environmental conditions can have a major effect on switch life.

Individual assessments for specific applications are possible and can be undertaken by Johnson Electric on request. Please ask Johnson Electric if you would like an assessment for your specific application.

Mechanical Life - the figures quoted relate to the number of switching cycles made without an electrical load.