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[crock]

Hi, having just blown-up my electronize ESC on some seaweed !!  Doohh   I'm after some advice on a replacement, thinking Action electronics ?  Graupner 700B turbo X45 prop 14.4V drawing  ?? amps.

Also much advice re fuses required ( oh for hindsight beforesight !!) .   How do I fit and where and what size etc ?  fuse holder ?     It would have been much easier had I stuck to 12 V ........


Thanks in anticipation  as always


Crock 

[malcolmfrary]

For fuse size -
Check the amp draw under load straight off the battery (no ESC in circuit)*.  Once you know that, you need the next size up of fuse, then you need the next size up of ESC so that the fuse can protect the ESC.  If the motor under load takes, say 10A, it needs a 15A fuse, and at least a 20A (UK amps, not Chinese) ESC.
Fuse holder -
Get an in line holder for a blade type from somewhere like Halfords, fit it between battery and ESC.

Dead ESC -
It is quite possible that the item blown on the ESC was the output transistor.  If the number is readable, it can be changed.  If excess current has fried the relay contacts relays are available.  In both cases, I'm assuming that the ESC is the type that I am familiar with, having a relay for reverse and a single output transistor.


* Use an ammeter, or just start with a lowish value fuse and try higher values until you find one that doesn't blow under load.  That's the one to go for.

[django]

I have had a couple of speed controllers burn out over the years & each time the fuse even though lower rated than the speed controller has not blown .I still fit a fuse for peace of mind though.    Django

[NFMike]

I have had a couple of speed controllers burn out over the years & each time the fuse even though lower rated than the speed controller has not blown .I still fit a fuse for peace of mind though.    Django

Fuses are a lot more complex than most people realise. (Like most things in fact ... such as concrete.)

A standard fuse isn't generally fast enough to protect a semi-conductor (s-c), unless the s-c can handle many times the current the fuse is rated for - ie. the s-c is significantly over-rated.
Even with twice it's rated current flowing it can still take a standard fuse some seconds to heat up and melt whereas s-cs tend to have less thermal capacity and overheat sooner.

You really need to use fast blow fuses if the fuse rating is in the same ballpark as the s-c.

[Covert]

Would you be better using glass fuses then rather than standard car ones ?

[inertia]

The primary reason for fitting a fuse is safety, not to protect semiconductors. As has been explained, a fuse will not blow fast enough to stop a high current from killing a MOSFET but it will blow by the time any wiring or other conductors get hot enough to catch fire.
DM

[NFMike]

Would you be better using glass fuses then rather than standard car ones ?

Only to the extent that you can get fast blow types in that sort of housing. I doubt car fuses give a choice.
As inertia says, fusing is generally about safety so standard fuses are designed to protect the cables not the appliance on the end. Which is why trying to protect devices needs a bit more effort.

[malcolmfrary]

Would you be better using glass fuses then rather than standard car ones ?

Only if you can get the right mounting.  The normal in-line housing that you can get forms an extra fuse in itself, softening due to the fuse getting warm to the extent that the spring pushes out.  Over time (sometimes not much time) this causes unreliable operation and eventually failure, usually in the middle of the pond with the wick turned up.
If the ESC carries its own protection, this "should" protect it against overloads coming from the motor.  If it doesn't, or there is something else wrong, the fuse protects the boat.  You get the chance of seeing it drift in, or just as likely, away, but importantly, you don't see clouds of smoke and flame coming out of it.
Fuses do not protect electronics, they protect AGAINST electronics.

[john44]

Thats why I use car fuse Battery side ACtion inline fuse holder motor side.

john

[Covert]

John could you post a picture for me ?
As im not running any fuses at the moment, hence why im interested .
Thank you Mark 

[Stavros]

http://www.componentshop.co.uk/leads-and-connectors/fuses-holders.html

http://www.componentshop.co.uk/indicator-fuse-boards-treble.html

Dave

[john44]

Thanks for that Dave,
Mark, they are the parts that I use, fitting inst. included.

john