If the relative humidity setting is exceeded, a heating element is switched on. This causes the temperature inside the cabinet to increase and the relative humidity to fall back to the controller setting. This process prevents the humidity from reaching its dew point and consequent formation of condensation.
Thumbwheel setting dial, grey scale.

The electronic Hygrotherm senses the ambient temperature and relative humidity in enclosures and cabinets with electric/electronic components and turns on a heater (or alternatively, a fan) once the set point is achieved, helping to prevent the formation of condensation in the enclosure. The LED integrated in the adjustment knob on the active controller is lit when the connected device is in operation.