Small hydropower station control and protection circuit

The circuit is equipped with over-voltage, over-current and overrun protection. The load power supply can come from the power grid
or from small hydropower. There are contactors KMl and KM between the power grid and small hydropower. interlocking.
  When the terminal voltage exceeds the specified value, the overvoltage relay KA is closed, and the contactor KM is: released when power is lost, and the load is cut off,
etc.; at the same time, the contactor KMs is powered and closed, and its main contact is connected to the water resistance to prevent overrunning accidents. occur. When the load exceeds
the set value, the overcurrent relay KI is closed, and the KMz is de-energized and released, cutting off the load circuit. At this time, the terminal voltage will inevitably increase,
and the overvoltage relay KA will operate, thereby putting the water resistor into operation to prevent overspeed accidents.