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Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Hi!
The alternating current reactor, also know as ballast, inductor, or even a inductance, is a coil with a magnetic core that has a small air gap.
The MOT primary coil normally is rated 5-10 amper, and the number of primary turns (120~180). This is enough to allows the core works bellow the iron saturation area when 120Vac is applied. So, the primary coil as is is suitable to work, without any modification.
Then we need to provide a air gap is adjustable (0.1 ~3.0mm) between the E and I cores. The result is a variable reluctance to the magnetic flow and a variable inductance. In this applicationthe the final effect is similar to a reostat in serie with the PT primary, allowing adjustment in the primary ac current. The MOT modification consist in open the transformer magnetic core, remove the high voltage coil, close the core leaving a small air gap between the I and E core. In order to get good and practical core closing, the air gap may be filled up with a hard cardboard, plastic sheet, fiber material.
A tutorial explaining how to open the transformer the may be found in the site:
or read the thread "windings in a mot" , posted on march 31 2012.
(be more carefull to avoid any damage in the primary coil.)
I'd like see your solution how to provide a mechanic variation of the gap.
Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Hi All!
I have cut the transformer core welding by hand using a arc saw, hss, not a power grinder.
When I cut the the magnetic core in order to separate the I and E cores, I do not cut exact in the midle of the welding core .
The saw open a slot 1mm out of the welding center, in such way that the E core is not damaged. only the I core receive 1.5-2 mm deep scratch. When reasembling the E core with the I core invert the I core leaving the scratch out of the main magnetic flux.
If the cut is locate in the center of the welding, both E and I cores will be scratched, resulting in a reduction of area of magnetic flow (increasing the induction in that location), possible saturation
Registered Member #3616
Joined: Fri Jan 14 2011, 08:47PM
Location:
Posts: 34
[Update]
I have purchased this amazing 35kv beauty, and it works perfectly...
With a half wave rectifier, my HV probe reads 18kv, so now I need to source a bundle of HV diodes in order to make a full wave rectifier. This one has 17 diodes and is rated for 100kv....
Does anyone know of a good supplier for HV diodes? I found Amazing1, but there most be other suppliers. I would probably need 50 or more to make a full wave rectifier capable of taking the 35kv from my potential transformer.
One more question if I may...
Not having played around with potential transformers before, is it recommended to ballast them? When I had the pole pig, I used 4 stove elements in parallel as ballast and that worked well. A half dozen 500w halogen bulbs in parallel also worked and gave visual feedback when charging the capacitors (lights dimmed as charge increased).
I don't want to cook this 150 pound potential transformer - it wasn't cheap, and from what I can tell, it was a rare find!
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Need 30 kilovolts!
