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Author Topic: Lack of sleep (Fuse or not to fuse?)  (Read 9332 times)

rem2007

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #25 on: August 24, 2008, 10:27:59 PM »

actually, his boss told him to count the number of ceiling tiles so he could suss out the paint required for re-decorating...psst martin, wake up... :D
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barry park

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Re: Lack of sleep
« Reply #26 on: August 24, 2008, 11:58:50 PM »



Just reading back on my posts here, maybe I should make myself clear... FIT FUSES!
Any additional form of protection for your expensive electronics is highly recommended.

Has anyone used those electronic type fuses / circuit breakers? I hear they react very fast!

... do as i say not as I do!   ::)


If medals were awarded for speed
GOLD    http://www.datasheetcatalog.org/datasheet/siemens/BTS555.pdf
SILVER  http://catalog.tycoelectronics.com/catalog/feat/en/s/23161?BML=10576,17593
BRONZE Fuses
They all have pros and cons.
If tyco parts are what you mean by electronic I'm drowning in them and use them.


 
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malcolmfrary

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #27 on: August 25, 2008, 12:00:46 PM »

Quote
Quote
2. I only use electronic speed controllers with overload protection or thermal shutdown.

.... and the advantage of a built  in device is it fast enough to protect itself and usually they automatically reset.
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.
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #28 on: August 25, 2008, 02:47:01 PM »

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.
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John W E

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #29 on: August 25, 2008, 03:38:23 PM »

hi there Rem2007

Will you do the rest of this forum & me a big favour my friend, fit an inline fuse to your motor setup in your picture you have shown.    Let's be done with it.   Before we get a 6-page essay from barry park  :) :)

Only several people could understand and would be interested in a 6-page essay.

The other people on here want to have a good discussion/build models and sometimes sail them.....

aye
john e
bluebird
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John W E

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #30 on: August 25, 2008, 03:39:56 PM »

You know John you have more than a passing resemblance to Martin, pose is very similar to. Did your Dad have a bike. :angel:

Dicky me dad had a pushbike but I don't think he rode it doon to Peterborough  :D :D :o :o ::) :-\ me dad never told me owt about it anyway.

ps Dicky when I first read your comment last night - I was too tired and mis-read it....instead of reading 'resemblance' I thought you had typed get a passing ambulance hahahah  - wonder where that came from.

Aye
john e
bluebird
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DickyD

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #31 on: August 25, 2008, 03:54:19 PM »

Hi John
Had a word with Robert this morning and he is fitting a fuse.
He could not quite see how his simple question could get certain people writing volumes of techno babble for so long.
Could he be on about the thoughts of chairman barry park do you think. ? :-\

What would you be wanting an ambulance for then ? :angel:
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #32 on: August 25, 2008, 07:28:02 PM »

Lightning fast fuses for semiconductor protection  http://en.wikipedia.org/wiki/Semiconductor_fuse

Six pages  {-) http://en.wikipedia.org/wiki/Fuse_(electrical)
Barry Park
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Stavros

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #33 on: August 25, 2008, 07:44:02 PM »

Well Dicky you were so right what a load of twaddle that guy posts I think it is a sad case of you will listen to what i say and do as I am right all the time,funny thing is we have not seen one of his installations or even a boat!!!!!!!!!!!!!!!!!!!!!!!



Stavros
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rem2007

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #34 on: August 25, 2008, 10:11:38 PM »

well I would install it, only its a bank holiday and I'm really not doing much aside from picking up after you know who. besides that anyone i'd purchase gear off  was at ellesmere and seeing as I live in a foreign country, I have to wait til these nice folks get back to work.
curious how one simple question can cause such good hearted debate amongst the model boat community :o, never mind, consider the culprit dilemma rectified O0
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wombat

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #35 on: August 25, 2008, 11:11:20 PM »

OK, my take on fuses and so forth.....

1/. Always fuse at least the main line from the battery. Select the fuse so that there is no nuisance tripping under normal maximum operating conditions. This protects the whole installation from wiring failures or from failures in the electronics. I have started, on the larger installations, to fuse the feeds to the motors to prevent meltdown of the ESC in the event of the motors becoming jammed. Use normal automotive grade fuses - they are good enough for most cases.

2/. I see no benefit in using semiconductor rated fuses - the fast fusing does not really give any additional protection - the drive transistors in the ESC should be designed to have sufficient overload capacity for inrush - if they cannot cope with a significant short term overload then buy a different ESC. Bitter experience tells me that semiconductor fuses do not fuse fast enough to protect FETs.

3/. Don't rely on active protection schemes - they are not fail-safe. In the event of a failure of the component your protection scheme is out of the window. Remember, standard failure mode of a FET is short-circuit. An intelligent high-side switch (for example) relies on being able to turn itself off to protect itself - if it has failed then the protection is shot.

4/. Circuit breakers - by all means use them, better yet - use a fuse and send me the money you have saved on the breaker. If you are getting enough nuisance trips that you need to keep popping the breaker back in, then there is something wrong elsewhere - fix the cause rather than the symptom. If you do use breakers, use magnetic breakers rather than thermal ones - thermal breaker operating current is too dependent on ambient temperature, especially with the self resetting ones (been there, done that).

5/. Polyswitches - never used them (at least on a model boat), but again, like a circuit breaker - if you are getting nuisance tripping, address the cause rather than the symptom. Remember that a polyswitch does not open in the same way as a fuse - it keeps a flow of current going. Also it does not give an indication of tripping - as soon as the power is off it self-resets.

OK so I am a conservative at heart - but I fail to see any significant benefits of using anything more complex than a simple automotive type fuse.  Also do not worry too much about the rupture capacity fuses - if the fault current is high enough that you risk rupturing the fuse then perhaps you shouldn't be running the model off the mains.

Absolute minimum fusing - a single fuse in the positive line, use smallest value that prevents nuisance tripping.
Normal practice - Fuse in the positive line plus one in each motor positive line.
Belt/Braces and piece of string - as above but also a fuse feeding each ESC.

Wom

 
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Stavros

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #36 on: August 25, 2008, 11:27:19 PM »

Oer thats a long post for you



Stavros
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andygh

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #37 on: August 26, 2008, 12:15:48 AM »

Long? yes, but at least I could understand it all, unlike some of the other "helpful" advice  :'(
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wombat

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #38 on: August 26, 2008, 08:25:53 AM »

Oer thats a long post for you



Stavros

Nah, wait till Wombat's authoritative tome on model boat electrics comes out - this topic will get a whole chapter not just a couple of short paragraphs. I didn't even mention the correct grading of fuses or the relative merits of time delay and fast blow fuses. Or automotive versus HRC, or indicating fuses

Put it this way - got four pages in on wire and still got to actually talk about specific wire

Wom
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #39 on: August 26, 2008, 06:33:37 PM »

Hey Wombat,  more info please!

For those old codgers who use braces ,but no belt, here's my definition of your "string"

A big shunt diode will protect an ESC , in conjunction with a fuse ,where the person is COLOURBLIND i.e. prone to connect the battery the wrong way round.
A reverse-polarity induced fault current is likely to destroy fully electronic (non-2-pole relay ESC's ) on 12 volts even when a fuse is present.
An alternative is a low resistance FET transistor to block reverse voltage altogether.

My semi fuse ref was only because Martin said he heard polymer PTCC's were faster than fuses (I think thats what he meant)
Like you, I know (i squared t) and have used up a few sheets of log graph paper too! :)
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DickyD

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #40 on: August 26, 2008, 06:52:42 PM »

Please Wombat dont encourage him he dont need it, he's a self winding, how do you spell geek, is that right ?.  :-\



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Stavros

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #41 on: August 26, 2008, 10:00:10 PM »

DickyD     O0




stavros
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malcolmfrary

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #42 on: August 27, 2008, 10:42:19 AM »

It doesn't really matter how much protection is built in, someone, somewhere, will find a way round it.  I know this having either seen the results or done it myself.  The suicide diode, provided it can outlive the fuse, works well, but there will always be somebody who puts a bigger, better fuse in.  There will always be somebody who, when presented with a blue and yellow pair of wires with instructions to connect them to the motor, and a red and black pair with instructions that these go to the battery, will shuffle them, because he did it with his trusty Bobs Board.
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #43 on: August 27, 2008, 03:41:38 PM »

It doesn't really matter how much protection is built in, someone, somewhere, will find a way round it.  I know this having either seen the results or done it myself.  The suicide diode, provided it can outlive the fuse, works well, but there will always be somebody who puts a bigger, better fuse in.  There will always be somebody who, when presented with a blue and yellow pair of wires with instructions to connect them to the motor, and a red and black pair with instructions that these go to the battery, will shuffle them, because he did it with his trusty Bobs Board.
That is so true! {-) It must be all the solvents they huff !
I just wish someone would publish a solution to putting yellow & blue to batteries.
 
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malcolmfrary

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #44 on: August 27, 2008, 04:23:09 PM »

Its really a Darwin sort of thing.  Although its rarely fatal, once, where you have to pay for it, is usually enough. 
The protection in modern units is already pretty good, the big problem is defining the limits of electrical devices for people who are very very good at shaping wood.  If they can refrain from laughing at my floating logs, I will accept that electric will remain a mystery to them.

If its a simple system, a fuse at the battery positive is enough.  A more complex system, with multiple motors and/or accessories would be better with a disribution panel.  Putting too many protective devices into a system eventually becomes a fault liability.
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barry park

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #45 on: August 27, 2008, 05:33:52 PM »

Its really a Darwin sort of thing.
  I tell you! It's solvent abuse! 
Quote
   
  Although its rarely fatal, once, where you have to pay for it, is usually enough. 
The protection in modern units is already pretty good, the big problem is defining the limits of electrical devices for people who are very very good at shaping wood.
And what do they stick bits of wood with?   
Quote
If they can refrain from laughing at my floating logs,
Aha !
Quote
I will accept that electric will remain a mystery to them.

If its a simple system, a fuse at the battery positive is enough.  A more complex system, with multiple motors and/or accessories would be better with a disribution panel.  Putting too many protective devices into a system eventually becomes a fault liability.
[/size]
Malcolm, I only put the thing in the diagram into a sealed compartment after accidentally reversing the battery on week one. (I can't fit a normal comnnector.)You can put it in a potting box with a glossy label on it,add two LED's and charge 16. I'll post it on an open forum for the vero enthusiasts.
Barry Park
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OMK

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #46 on: August 27, 2008, 06:48:31 PM »

Guys, guys -

Many moon ago, when a certain sinful lady used to frequent these pages, I seem to recall a helluva lot of members who took a whole load of delight in kicking the crap outta her. And all because she had the balls to speak her mind.... even though what she said was always the truth. Remember?
That was a long time ago. But since then I thought that we had grown up a little - started acting a tad more civil towards fellow members.
Then I tuned in tonight and was genuinely surprised to see that the very same mentality still rides loud and proud on Mayhem.
Guys, listen to yourselves. I mean, if you MUST bad-mouth Barry Park, then at least to do it in private... or at least with a hint of style. Real men would have sent him a PM.  Instead, everything I've read here tonight merely  tantamounts to nothing other than plain rudeness.
I'd bet my aunt Fanny's panties that all those making all the noise would be the FIRST to go running to Martin if it were happening to THEM (right?).

Give the man a chance, for Gawd's sakes. You don't HAVE to like or even agree with what he says. But to be so RUDE about it??

Barry Park,
Dude, I'll take the curtesy of using upper-case initials on your name - even if you won't. You come across as the sort of bloke with skin as tough as a buffallo's butt. But there is no doubting your that you do indeed have a head for electronics. For may part, I come into 'my-boats-look-like-logs' catagory. I think the buzzword for people like I is 'nerd' / 'geek', blah. Personally, I much prefere the term 'love god', but I daren't say that for fear of causing a whole shipload of jealousy.
Instead, what are the chance of seeing that Veroboard layout you talked of?


Dances With Fuses.
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Circlip

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #47 on: August 27, 2008, 07:40:18 PM »

Forever the pacifier PMK,  O0 at least there will always be some semblance of sanity and tolerance while you're posting :)
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OMK

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #48 on: August 27, 2008, 08:38:19 PM »

Pacifier? Isn't that one of those things that our Yanky cousins shove in their kiddies mouths to stop 'em squawking?
What do we call the same thing over here?... A dummy?
Thanks, Circlip (I think!).

At the risk of sounding like a dummyfier, am I the only one who happens to like the simplicity - not to mention functionality - of BP's circuit?
Talking of fuses... Whatever happened to the so-called 'crowbar' circuit? Wasn't a silicon-controlled rectifier supposed to work MUCH fast than a fuse?
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rem2007

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Re: Lack of sleep (Fuse or not to fuse?)
« Reply #49 on: August 27, 2008, 08:47:20 PM »

Done and dusted.... sorry I started this little tete-a-tete.....always thought a pacifier had something to do with the people who lived near the pacific ocean :D
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