Controlli MVA actuators are electro-thermal type and are controlled by an on-off signal or, for MVA41/42 only, by pulse width modulation too. Actuators are supplied by control signal; this causes the thermostatic element to heat up and a small piston to come out and lower the valve stem. MVA22-42 actuators are supplied with a 2 (0.2)A 250 V SPST microswitch with contact closed by powered actuator; a particular application of fan control terminal unit being: the fan, connected to microswitch contact on the actuator, operates by open valve and stops when valve is near to full close position.
