Glossary of Terms

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  • Dome:Dome-shaped metal elastomer switch component used as tactile element/return spring.
  • Double Break:A contact mechanism using two sets of contacts to make or break a given circuit. The contact gap opens twice as fast, reducing the arc duration, contact surface temperature and material erosion. This improves heat dissipation and provides better power handling capacity for a longer switch(...)
  • Double D:Flat edges on two sides of a cylinder used for orientation and anti-rotation.
  • Double Throw:Contact arrangement that allows current to flow from the common terminal to a normally closed terminal and then to a normally open terminal. Please refer to the ITW Switches Characteristics/Circuits for more detail.
  • DPDT (Double Pole Double Throw) Switch Configuration:Double pole means two independent circuits are actuated by the button. Double throw means the common terminal of each circuit (pole) can transfer current to a normally closed terminal and then alternately to a normally open terminal.
  • DPST (Double Pole Single Throw) Switch Configuration:Double pole means two independent circuits are actuated by the button. Single throw means each circuit only has two terminals and only operates as an on/off switch.
  • Dry Circuit:Low power level or Logic circuit. Power levels do not cause arcing, melting or softening of contacts. Typically requires gold plated contacts for reliable switch operation. At such low levels, and since no arc occurs, silver contacts would not be self-cleaned and would be less reliable.
  • Dusttight:Sealed switch that will withstand sand and dust environments per MIL-PRF-8805 Design 2.
  • DWV (Dielectric Withstanding Voltage):The maximum voltage that can be applied to an insulator or switch before it will break down and begin to conduct electricity.
  • Electrical Life:Life of a switch (number of operations) under a specified combination of electrical load, actuation, environment, and criterion of failure.
  • Electrical Load:The amount of electricity that is applied to the switch or the circuit.
  • EMC:Electro-Magnetic Compatibility.
  • EMI:Electro-Magnetic Interference.
  • Environmentally Sealed Switch:A switch that is sealed to protect the internal contacts from the external environment.
  • Erosion (Contact):The transfer or vaporization of contact material resulting from the arc due to breaking or opening the circuit.