They consist in using the property of perfectly studied electrolytes that diminish their resistance as they increase their temperature by thermoelectric effect: This variation occurs in a small Inter-electrodical chamber.
The resistance is connected in series with the motor windings, causing a voltage drop that reduces the starting torque and the absorbed intensity of the line.
As the engine speed rises, an automatic reduction in the value of the resistance is produced, resulting in a gradual increase in the voltage at the motor terminals, which provides a smooth acceleration with no torque or tips of Current.
It is based on the resistivity difference between an electrolytic fluid and its vapor, contained in a electrodical chamber.
The passage through the electrolyte from the initial current of the rotor immediately produces a partial vaporization of the electrolyte with an instantaneous adjustment of the resistance and the starting torque to the optimum values.
During the speed rise, a thermal exchange is produced which gradually condenses the vapour, thus automatically decreasing the resistance.
At the end of the starting period a timer actuates a contactor that shortens the motor rotor, eliminating the resistance of the rotor circuit.
The starting torque is adjustable depending on the concentration of the electrolyte (higher concentration, less resistance and more torque) and is determined according to the type of machine dragged or the limiting of the starting intensity.
The temperature of the unit is controlled by a thermostat and any abnormal drop in the electrolyte level is detected by level control lamps.
At the end of the starting period a timer actuates a cortocircuitaje contactor that eliminates the resistance of the circuit