[Amel] Re: Genoa sheets and runaway winches


Craig Briggs
 

Bill,

"Runaways" , as you say, are most certainly a failed switch closing the
low current side of a relay, which in turn energizes the electromagnet
that closes the hi current terminals.

To address Kent's question of whether flipping off the panel switch
eliminates all possiblility of a runaway and Bill's second scenario of a
solenoid failing and going to the closed position - there is virtually
no realistic chance of such a failure and turning off the panel switch
is definitely "enough" as Kent put it.

These relays/contactors/solenoids - whatever term you wish - are highly
engineered devices that have their high current terminals held open by
strong springs (some are normally closed, but ours are normally open).
They are designed so that any realistic failure mode will not activate
the switch. Bill, I guess I can't disagree when you say this "could"
fail - but it's in the realm of an irrelevant hypothetical, not real
life. Oh, I suppose if you had dripping sea water making it a massive
corroded wad it could fail - but, hey, these are Amels!

Thus, unless and until you hit the switch (or the switch fails and
closes by itself), thereby feeding low amp current to the electromagnet,
thus closing the contacts, the relay/solenoid will not energize the high
current side - period.

This is NOT analogous to "hot wiring" a car (and I grew up in Detroit
when we could still do that!). Hot wiring is simply bypassing the switch
with a jumper, which IS totally analogous to the failed switch scenario
- not the failed solenoid scenario.

I'd suggest some KISS, and just turn off the panel breaker - a simple
routine easily made habit. It will, ideeed, eliminate all reasonable
possibility of a failure and, more important, it'll get done. Can't
quite see traipsing around after every sail from engine room to
companionway to bow to open breakers becoming anything but a PITA.

Having said all that, this part is really not too important. What's
really, really important is that all the crew know exactly what to do
with a runaway.

Bill - sounds like we may have crossed paths as you're in Crete and we
just left there and are now in the Dodecanese. Will you be headed back
this way or to Turkey - would welcome you for sundowners. Ever come up
on the Med Net?

Cheers,

Craig Briggs, "SANGARIS", SN#68

--- Bill aboard SV BeBe" wrote:
.. breaker ..only turns off the low-amp side .. high-amp side remains ON
when the 24v panel breaker is OFF. If any of the relays/solenoids fails
and closes the high-amp side, the motor will run with .. breaker set to
OFF. Some of you may remember "hot wiring" a starter solenoid on a car
with the key switch OFF...same principle. (NOT THE SAME PRINCIPLE -
Craig)

In my opinion there are two possible/probable causes of a runaway
electric winch:
---One is if the winch/windlass control button fails and closes...this
will cause the winch to runaway if the 24v panel breaker and the
high-amp breakers are ON.
---The other potential cause could be if the the relay/solenoid fails
and closes, the winch will runaway even if the 24v panel breaker set to
OFF. ("COULD", BUT SO IMPROBABLE AS TO BE IRRELEVANT - Craig)

Bill
BeBe, SM2k, #387
Crete, Greek Islands

Kent Robertson karkauai@ wrote:

If the winches are turned off at the 24v panel, does that shut off
all possiblity of the winches running, or do you have to turn them off
at their individual breakers or even the primary 24v breaker at the
battery bank?
We've always turned them off at the 24v panel, but now I'm
questioning if that's enough.
.....

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