RTRDU 3 Phase Trickle & Boost 5 Step Speed Controller - 4 Amps

A three-phase transformer which controls the fan speed by altering the supply voltage in five fixed steps. The steps are adjusted manually, using the control knobs on the front of the unit.

There are two control knobs: one for higher fan speeds and one for lower fan speeds. Switching between the high and low settings is done by an external change-over contact, which could be a thermostat or a timer.

An integral motor protection device is included which cuts the supply voltage to the fan if the thermal contact in the fan motor is activated. The unit is reset by turning the switch to 0 for 10 seconds, after which the unit restarts.

Input terminals for room thermostat RT cuts supply voltage to the fan when the circuit is broken. Terminals are linked before delivery. The indicator lamp on the front shows when the transformer is in operation.

The transformer has 230V terminals for operating dampers, electric heater batteries or other external equipment. These terminals have no current when the transformer switch is in position 0, or when the TK or RT input is open. Supply voltage: 400V 50/60Hz.