What and why a dump load?

Wiring, circuits, batteries etc.

What and why a dump load?

Postby windgat on Wed Mar 18, 2009 10:06 am

The more current drawn from a wind turbine, the slower it goes. If no current is drawn, then it speeds up - in a strong wind, it will go frighteningly fast.

So when the power is not needed, it is not a good idea to just disconnect the wind turbine from the circuit (this is the normal procedure for solar panels).

If you don't want to watch the battery voltage and manually turn of (and brake) the turbine, you need a control circuit which does this for you.

One way it to use a relay to disconnect the turbine from the battery, and simultaneously short out the turbine, causing it to slow down. This is not a good plan for lots of reasons, such as mechanical strains and relay life.

A better way is to have a 'dump load', such as a bank of powerful light bulbs, which is electronically turned on when a set voltage is exceeded.

Such a circuit need to have a hysteresis - this means it should turn on the dump load at a certain voltage, and off at a slightly lower voltage. Usually FETs (field effect transistors) are used to do this.
windgat
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