shorting schenes for braking

[kitestrings]

This may be a lobbed pitch over the plate, but it is a question I've been wondering about:

In schemes where folks are shorting the windings for braking, is it best to short the windings while connected, or to isolate the rectifier and controls?

We were considering putting a braking switch at the base of the tower (as a parking brake primarily).  I had invisioned a 3-pole transfer switch where the turbine was the common set of contacts, and one set of poles was shorted.  In this scheme you would simultaneously short the windings and isolate the AC line to the controls.

Neilho had suggested simply shorting them with a 2-pole switch, something like this:
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I believe a SWWP turbine that we repaired awhile back used this method.  It sure seems simpler and cheaper.  My question is there any risk to other components (rectifier, controller, etc.), or other danger or disadvantage?

~kitestrings

[TomW]

I stop / brake mine by shorting on the AC side of the rectifiers (Like your diagram). You don't need anything fancy just a 2 pole switch that can take the voltage & current from the turbine. Nothing to disconnect just flip the switch and it shorts all 3 turbine leads together.

Tom

[Flux]

All depends on where your rectifier is.

If you bring ac down the tower then you can just short the ac connections with a switch ( 2 or 3 pole) If the rectifier is up the tower and you bring dc down then things are a bit awkward as you can't short the dc side without isolating the battery. You then need a change over switch or some means of temporarily inserting a series blocking diode.

If you short on the ac side of the rectifier there is no point in a change over switch or anything complicated, it is just more to go wrong and the open circuit transient between change over is not good.

Flux