The wind turbine is connected to the over-voltage trip
first, and then to the other loads.
If the other loads become disconnected, then the voltage will rise, and
the over-voltage trip will operate.
The over-volt trip contains a dump load that can dissipate
the turbineÕs output and that will tend to stall it when the wind reduces in
speed. This dump load is connected
by default. Active intervention is
needed to disconnect this dump load.
The circuit is fail-safe.
A power source such as a battery or the mains is needed to
power the circuit (a watt or two of power). This power source energises a relay that turns the dump load
off. The dump load is connected to
a Ônormally closedÕ (N.C.) contact.
When the relay is energised then the load is off.
The relay itself has a second set of contacts. When it is on it holds itself on, but
if it is off then it can only be re-energised by bypassing the second contacts
with a rest button that latches it back on, disconnecting the dump load and
allowing the wind turbine to run and produce full power.
Finally you need a second relay driven by the wind
turbine. It is fed via a
potentiometer (variable resistor) so that you can adjust the voltage at which
it clicks over. When it does so it
disconnects the first relayÕs power source so that the dump load comes on and
the wind turbine is ÔtrippedÕ.
After that it will not run fast without a manual reset.