current limiter circuit

Here's a start:

Have Fun! Rich

+regulator+di...

thanks it is so interesting !

"refigh"

** This might be what you need.

Don't be afraid to give us the details of what you are doing.

Get much better advice that way.

.... Phil

start:

I'm glad you enjoy it - do google (or lycos, or yahoo, or any convenient search engine) on any electronic term while adding "tutorial" to the search string.

And Welcome to the Loony Bin! ;-D

Cheers! Rich

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The resistance of the limiter will depend on the voltage across the
source, the voltage across the load, and the current through the load.

It cannot, therefore, be arbitrarily specified, since it will be what
it will be,

When you say high current, to me, that is in the hundreds to thousands of amps at some voltage far above 100 volts..

Clarification of those specifications will make it possible to better assist you.

Jamie

There are four or so choices:

1. A real analog, continuous current limiter. It will get hot if the load shorts.

1. A foldback limiter. Doesn't get as hot.

2. A simulated fuse, like a polyfuse. It opens if the current gets too high, but you have to kill the power source for a while to reset it. Polyfuses aren't very precise.

1. A device that senses over-current and opens up, but retries periodically. Ancient Ford pickup trucks had these, a bimetal-based self-resetting fuse. It can be done electronically, of course. I'm designing a circuit right now that needs such a current limiter.

We were having a burger today at In-n-Out and the guys at the next table were talking about "reclosers", and I had to explain to Mo what they are. It's a circuit breaker, used in AC power systems, that will open up on overload but attempt to re-close the circuit automatically, some number of times, before it gives up.

John

Recloser testing is one of my specialties. I have a patent on a recloser =

test set:

More recently I developed an improved measurement device called an=20 Ortmaster:

and now I have a more modern version:

A typical recloser has two fast and two delayed operations, with about 1 = to=20

2 seconds between tries. The first two are designed to recover after=20 transient events such as lightning, wind-blown wires touching, and tree=20 branches. The delayed shots maintain fault current for up to several = seconds=20 in an attempt to burn off the source of the fault, which could be a = small=20 tree branch or an animal such as a dreaded squirrel, which would then = become=20 a "crispy critter"

Paul

Sounds dramatic. In EE school one day they showed us a film of the LA power department test yard "greatest hits", massive explosions and arcs and fireballs from transformers and breakers and stuff. Fun.

When I blow up a SOT-23 opamp, it makes a tiny pip! at best. Electronic design isn't very macho, but it does keep us out of the rain.

John

I saw a movie by Bussmann (now Cooper) showing the difference between a=20 standard low voltage (600V) MCCB with about 10kA interrupting rating=20 compared to a current limiting fuse. Even with the current limited to =

10kA,=20 the circuit breaker was damaged and had to be repaired before it could = be=20 used again, but at the full 200kA it blew up quite dramatically. The LPS =

fuse just shook a little bit and let out a small puff of magic smoke.=20 Youtube has some good videos of high voltage arcs and accidents:

(60A thru 20A breaker - actually a 3x = overload=20 may be 60-90 seconds trip)

Tour of a recloser shop which uses a Phenix Technologies test set.

I worked for them 1990-1992 at their shop in Accident, MD. Previously I = had=20 worked at EIL which was in Sparks, MD. Good names for towns where = electrical=20 testing is done!

This an interesting test of a fast-operating recloser vs one with longer =

closed intervals:

A nice overview of an Aussie switchgear mfr:

Here is a video by one of my customers:

I repaired (actually replaced) his 13 year old Ortmaster when it had = been=20 run over by a truck in an accident. The D-sub connector had broken but = the=20 unit still worked when I bent it back into shape. The enclosure is 14 = gauge=20 steel. Now that's rugged!

Thanks,

Paul