8.11.2.3 Tachymetric generator As in all motors powered in series, the speed of the commutator motor depends on the load. In other words, its speed diminishes as the load increases This makes it necessary to ensure that the power voltage to the motor, and therefore its speed, be constantly controlled by an electronic speed control system. A tachymetric generator (consisting of a magnet fitted to the shaft and a coil) generates a voltage that depends on the speed of the rotor, which is transmitted to the electronic control system.
All electronic control systems feature a system of protection (which may be more or less refined) to prevent operation of the motor in the event of a fault in the tachymetric generator. M Electronic control system P Motor overload cut-out S Stator R Rotor T Tachymetric generator TY Triac R1,2 Reversal relay 8.11.3 Electrical symbols Stator Rotor Tachymetric generator Overheating cut-out SOI/DT 2002-05 eb 80 599 35 23-17