Electronics > Projects, Designs, and Technical Stuff
Designing a Burn Down Transformer
sinB:
Hello EEVblog, this is my first post.
I've had this project in mind for a longer period of time.
My goal is to build a crude, but safe, Burn Down Transformer for locating faults in 240V heating cables in combination with a thermal camera.
Example:
A heating cable is damaged somewhere in the floor, causing the fuse to trip. The cable is then hooked up to the Burn Down Transformer, and a thermal camera is used to observe the exact position where the heating cable gets cold. The heating cable can then be repaired at that exact point.
There is of course commercial equipment available, like the Baur ATG2 Burn Down Transformer
(https://www.alpha-electronics.com/power-engineering/cable-fault-location/baur-atg2-burn-down-transformer.html).
Those are expensive, but looks relatively simple to build.
Here is the problem: I can't seem to find any designs or hardware documentation about Burn Down Transformers, not even simple sketches.
Does any of you have experience related to this or other inputs that can lead me in the right direction?
TERRA Operative:
I'd start with an isolation transformer (To get around earth leakage faults) and a beefy dimmer/current limiter.
It looks like a chunky PSU with a few mods to make is specific to this application.
digsys:
Agree with the Isolation transformer - A second option, which I've used in the past is a say 5A Variac, with VI meters. Just dial up slowly until you get to a reasonable current, then wait till the wire heats up. IF the short is very close by, and you can't dial up enough voltage, just wire in a series lamp etc It may even be good practice to leave it in. You'll soon find out how much current you need for detection.
MagicSmoker:
Calling something a "burn down transformer" sounds like the marketing fail of the century to me so I clicked on the link. It appears to be a current-limited, AC voltage source which can output switch-selected combinations of voltage * current that maxes out at around 2.2kVA, ranging from 60VAC * 32A to 10kVAC * 0.16A - yes, 10kVAC...
I can think of a few ways to do this off the top of my head, but none of them are cheap. How much is one of these things, anyway*?
* - one must request the price, which is always bad news for the budget...
Marco:
--- Quote from: MagicSmoker on July 22, 2019, 11:16:28 am ---Calling something a "burn down transformer" sounds like the marketing fail of the century
--- End quote ---
Since they actually burn the broken cable to create a more conductive path it seems accurate. It seems a bit foolhardy to me, but I don't do power electronics.
That said, it's massively overdesigned for finding a short in a heating cable. Using an isolation transformer with a lightbulb (and possibly a variac for more control) seems the most straightforward method.
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