7Actuators in Buildings

Actuator is a device that acts in accord with a control signal and performs a change of its state, for example the drive, which ensures movement or controlling of mechanism or system according to the control signal.

Actuators can be classified according to their physical principles:

With respect to the type of output variable, we can classify actuators into two categories. The first type can operate in two discrete states; for example:

  • Electric door lock, which allows to open a door based on the lock/unlock input;
  • Contactor, which, for example, switches a heater on when the temperature in a boiler drops below the set limit;
  • etc.

The second type of actuator has output variable, which changes between two limiting states; for example:

  • Control valve supplying gas to a burner of a gas furnace. According to the difference between the actual and the desired temperature, the valve is opened more or less to change the gas inflow.
  • Reducing valve – performs reduction of a fluid pressure and maintains the pressure at the required level.