About Solenoid

3 types of Solenoid performance


A lock can be maintained unlocked while the solenoid is energized. Provides good security since a door becomes locked and unopenable in instances where power is discontinued such as when power goes out or the power line breaks. Mainly used where emphasis is placed on preventing vandalism.


A lock remains locked while the solenoid continues to be energized. When power is discontinued, the lock unlocks. Since this allows a lock to unlock in instances where a power line becomes broken during a fire or accident, this type of solenoid is used where evacuation and firefighting considerations take priority over vandalism security, such as emergency exits.


The solenoid moves in either of two directions, to lock or unlock, and is then held unenergized at either position, by applying pulse voltage in either a positive direction or negative direction. This is an energy-saving solution as there is no need to maintain the solenoid normally energized.

Continuous rating and intermittent rating

  • Continuous rating indicates how long a solenoid is designed not to exceed a stipulated maximum temperature even if energized continuously at a rated voltage.
  • Continuous rating indicates a solenoid is designed not to exceed a stipulated maximum temperature when energized only a stipulated duration at a rated voltage.

With an intermittent rating, the temperature of the coil rises in 1-second intervals, and thus requires the energized (On) time and unenergized (Off) time to be set. This time proportion is termed the duty factor.

The duty factor can be found with the following equation.