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599 37 47-13
5.8.2.3 Tachometric 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 tachometric 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 tachometric generator.
EC Electronic
control
system
P
Motor overload cut-out
S Stator
M Rotor
T Tachometric
generator
TY Triac
R1,2 Reversal relay
5.8.3 Electrical
symbols
Stator
Rotor
Tachometric generator Overheating cut-out