Small hydropower station motor speed regulation and overrun protection circuit

In the figure, M is a speed-regulating motor, which controls the opening, closing and opening of the water guide vane.
    ①Electric speed regulation. Before connecting to the grid, turn the transfer switch SA to the generator side and open the toggle switch S; after connecting to the grid, turn SA
to the generator side to be paralleled and close S to achieve the purpose of tripping self-protection. When the generator is connected to the grid and the load is sufficient, the limit switch
SQi is opened and the motor stops running; when shut down, when the turbine guide vane opening is zero, the limit switch SQi is opened
and the motor stops running. .
    ② Speed ​​protection. When the generator fails, the circuit breaker QF trips, its auxiliary contact closes, the contactor KMz
is electrically closed, and the motor reverses until the limit switch sQz is opened and the shutdown is completed.