Circuit breakers

[nicebutdim]

Hi all. After my recent purchase of a TE, I thought I'd better protect it from short circuit as on the rare occasion this does occur with my reversing loops. I thought about fuses but wanted to give circuit breakers a chance first and found these http://shop1.actinicexpress.co.uk/s...x&ActinicSID=14d8ea43aef2a28b0557119dedce31e7 < Link To http://shop1.actinicexpre...f2a28b0557119dedce31e7 it's the Zing Ear ZE-700 breakers that I bought, one of 7 and one of 8 amp. My power supply gives out at least 10 amp, so I tried the 7 amp breaker in the track supply and tested it, no trip. I tried the 8 amp too and that didn't trip out either. I even momentarily placed the 7 amp breaker straight across the power supply output with no response. Now, I thought that breakers are only tripped by overcurrent and that lower than rated voltage should make no difference (breakers have a rated voltage that should not be exceeded as a higher voltage can bridge the open contact gap). The description also says suitable for up to 36v dc. Am I missing something? Or are these breakers simply not suitable? Has anyone here tried using circuit breakers as a form of protection for the track supply?
Many thanks,
Tim

 

[sparky230]

i wouldn't expect a 7 or 8 amp breaker directly placed across a 10 amp power supply to trip, would expect the power supply to shut down first.
The short circuit trip current of a breaker could be many KiloAmps rather than amps depending on the caristics of the breaker.
If you want short circuit protection use a Fuse or a Diode Stack.

 

[nicebutdim]

Ok, I see what you mean. I thought that circuit breakers were meant to protect from short circuit as well as overcurrent. Is there nothing resettable that could be used instead of a bulk supply of fuses?

 

[sparky230]

try googlng ptc or resetable fuses

 

[yb281]

Ok, I see what you mean. I thought that circuit breakers were meant to protect from short circuit as well as overcurrent. Is there nothing resettable that could be used instead of a bulk supply of fuses?

Sorry Tim, but what makes you think you'll need a bulk supply of fuses? I've had a TE for about 4 1/2 years and can only remember changing the fuse once ........ and even then, it turned out not to have been blown.

Having said that, my transformer and TE are both run off a plug-in RCD as well as being on an in-built RCD protected circuit. Can't be too safe with outdoor lectrics.

 

[Rhinochugger]

Ok, I see what you mean. I thought that circuit breakers were meant to protect from short circuit as well as overcurrent. Is there nothing resettable that could be used instead of a bulk supply of fuses?

Sorry Tim, but what makes you think you'll need a bulk supply of fuses? I've had a TE for about 4 1/2 years and can only remember changing the fuse once ........ and even then, it turned out not to have been blown.

Having said that, my transformer and TE are both run off a plug-in RCD as well as being on an in-built RCD protected circuit. Can't be too safe with outdoor lectrics.

RCD protected circuit is adequate - you don't need an RCD on the plug as well, unless your circuit isn't dedicated to the outside (garden) supply - don't want the trains tripping out SWMBO's sewing machine, eh? :impatient:

 

[nicebutdim]

I run automatic reversing loops, sometimes, for some reason or another the reed switch doesn't register the train, resulting in a short as the train leaves the loop. It has always been dodgy connections of my own fault that cause the problem, but sometimes things like the magnet dropping off have caused this to happen too. I was just after protecting the TE from the inadvertent shorts, like the one that occurs when you turn your back for 10 secs in hours of no problem running :impatient:
I'll have a look into the ptc fuses, are there any suggestions to the rating, as I see that some have a constant rating of, say, 5 Amps then a cut out at 10? I would like the cut out to come in at 8 amps really.

 

[sparky230]

look at this table
http://www.atcsemitec.co.uk/pdfdocs/sfr30f_series.pdf

theres one that trips at 8 amps

edit pasted wrong voltage table

 

[minimans]

Circuit breakers are a bit slow to trip, if you want to protect electronic circuits then you need to use a fuse (which also come in slow blow or fast blow types.) As the trip in the unit is set to protect it's 10amp rating if you wanted to protect a single remote circuit you need to place a fuse in the feed to that circuit only, at a perhaps lower rating but slightly above the maximum amps you expect to carry in that one circuit.

 

[nicebutdim]

Just been outside experimenting with some old car fuses (the old torpedo type from my first XR2). Quite surprising really. I was able to blow an 8amp fuse...just. The 5amp fuse seemed quite happy to carry 8amp without warming, but blew within 2 seconds of a direct short.
I think I may just take the easy route here and go for fuses. They're cheap and visually easy to tell when blown. I know they're not essential, but I'd rather have that peace of mind with this equipment.
Thanks everyone, at least I have a better understanding of circuit breakers now!

 

[spike]

All I have in my TE is the quick blow 10Amp car fuse.
It goes fast enough to save the TE .
If I had a £ for every trip thats never worked well.....

 

[Walts-Playmobil]

Circuit Breakers are designed to trip on A.C. If you are using them on D.C. read the small print you will find it states that they trip on 20 percent more current then the stated A.C. current.