It has been recorded in a thread on this site that a self-protecting ESC, having an internal fault, is perfectly capable of incinerating both itself and its surroundings if its supply is unfused.
Hi Malcolm,
You are correct spot on there ! Haven't seen that post but boats are in water (water and electrics don't mix.)
That reminds me ,P.T.C. breakers I have just mentioned ,by Tyco and Bourns and the like ,can shatter if badly installed so beware.
I don't yet know if that's what Martin meant in his post about "electronic fuses"
If you use said breakers the quickest acting type are the lowest voltage (RGEF @16volt) and also have the largest rupture capacity @ 100 amps.
They stay hot until the fault is removed.(DO NOT EXCEED VOLTAGE OR THEY'LL EXCEED 125 Celcius)
They
do not provide isolation and trigger times are longer for the physically big sizes.
I put a breaker between motor and ESC & blade fuse in
+ ve line (Manufacturer Tekin included a solder blob
in case the external battery was reversed) and added polarity protection.(I'll post a diagram if I find how to do that!)
Overkill some may say.... well no......each protection method has a function.When a weed problems occurs,it only triggers the breaker so I only need to lift the stern to de-fowl the prop and not take the beast out the pond.
As with fuses,every electrician knows your wiring must not permit a fault current to exceed rupture capacity.Breakers warm up due to their P.T.C. ,their resistance rises and effectively causes a near open circuit but a surge in excess of their rating may cause them to shatter.
The ideal place for such devices is between ESC and motor as the current is limited to the motor stall figure. My 550 would stall at only 40 amp so the breaker is safe (and has been proved to work).
These metal-oxide P.T.C. breakers are faster than fuses in the region of faults 2 to 5 times the nominal value ,as Martin asked. However,the voltage and low-ish rupture capacity shouldn't be exceeded.