Sciencemadness Discussion Board

OBIT heat control

Gooferking Science - 9-1-2014 at 18:19

Do oil burner ignition transformers heat up after running for a short period of time? I don't think they do, but I was just curious.

Metacelsus - 9-1-2014 at 18:55

However, if used properly, they have a long lifespan.

Gooferking Science - 9-1-2014 at 19:23

Could something be done to control the heat? It surprises me that they heat up, considering the low wattage. I suppose it could be ballasted, but that would make the output a lower current...

macckone - 9-1-2014 at 19:42

These are not designed to put out a lot of power,
just enough to ignite oil.
They are also designed to be fairly heat resistant but
not completely as there is no such thing.
Welding transformers use a duty cycle method of
controlling heat. ie. 4 minutes of use every 10 minutes
is a 40% duty cycle.

Such a scheme could work for an OBIT depending on the use.

NST (neon sign transformers) are a better choice as they are
designed for continuous use and generally higher voltages.

violet sin - 9-1-2014 at 21:25

I'm no expert first off, but I have SOME experience in the matter
after reading a few google search leads for OBIT heat up, I notice they can be wired in 2 ways. intermittent and continuous. one only energizes the x-former for starting the flame. the other way it is kept on the whole time while the unit is actively heating the house. so maybe check the model and see if it is rated to be used both ways. also a while back I was reading up on HV projects for big sparks and it was mentioned flybacks and OBIT's can be submerged in oil to dissipate the heat and increase life time. who knows how effective the suggestion is, as these were not trained professionals talking, but I think the idea has merit.

other things to keep in mind are the terminal spacing and erosion from continuous use( = greater spacing) from the searches. as the gap grows a bit it takes more to reach the other side like increasing a current limiting resistor. this eats the electrode tips at a greater rate as you might imagine further increasing your problem. you could look into the spacing specifications at the manufacturers site usually. found the one I played around with, and ignored it. I think it was only meant 2cm if memory serves. but I was using the transformer for a few min at a time. I can say that with mine, and an increased gap distance(~1.5in), after 10 min it was only warm and deff didn't feel like it was overheating. though the materials used in construction would dampen the spread of heat through the device. meaning it could have been much higher on the actual winding. I was experimenting with NO2 production with platinum tipped tantalum electrodes. not as fancy as the materials might imply, they were slapped together from some materials I had lying around( or kept safely in a hoard box, Pt :) )

it performed wonderfully at making NO2 in a short time. 30 sec was a light orange haze and better the longer you left it going. after a couple min it was nice dark orange/brown. I shut it down and cleared out of the basement after just a few min to let the NO2 dissipate( a med mason jar's worth). plenty for it to eat down there and I noticed no smell a few hours later when I went back to make sure nothing was plugged in for the night.

I would not recommend this type for O3 production though. just my take on it, the NST was MUCH better for this. despite it's cooler arc it still had no problem punching holes in dielectric materials. and once through good luck stopping it from punching right through the patches I attempted.

hope it helps. I been meaning to get back to that project for a while now.
-Violet Sin-

Metacelsus - 10-1-2014 at 06:03

The point of submersion in oil (at least for flybacks) is to push output voltage beyond specifications, which would normally result in destructive arcing. The oil serves as a dielectric. However, I could see how it could also help cool the transformers.

Gooferking Science - 10-1-2014 at 18:23

My intent with this OBT is to power a cathode ray tube for the Kansas science and engineering fair. I ballasted the OBT to 40 watts and the transformer had enough power to run a CRT. I think that at this low of a wattage (the OBT's rating is 250 watts) there shouldn't be any heating.