MOT ballast..
Zyrppa, Wed Mar 28 2007, 04:49PMHi.
I got MOT and after reading this forum, i realised that it needs ballast. I don't fully understand english, but i understood that ballast is coil that limits current coming from MOTs secondary, and it is installed in series with MOTs sec.
So, can i use flyback from TV ballast or will it just burn or melt? Or is it possible to use just some 230/12 or similar transformer as ballast?
Thanks.
Re: MOT ballast..
Dr. Shark, Wed Mar 28 2007, 05:01PM
Hi,
you don't necessarily need a ballast, you can try without, but it might blow your circuit breaker.
It is a lot easier to have the ballast on the primary side, and you will not be able to get away with a flimsy wall-wart transformer. Figure a piece of iron about as big as your MOT, with thick enough wire to support the 5A or so that the MOT takes.
Dr. Shark, Wed Mar 28 2007, 05:01PM
Hi,
you don't necessarily need a ballast, you can try without, but it might blow your circuit breaker.
It is a lot easier to have the ballast on the primary side, and you will not be able to get away with a flimsy wall-wart transformer. Figure a piece of iron about as big as your MOT, with thick enough wire to support the 5A or so that the MOT takes.
Re: MOT ballast..
cbfull, Wed Mar 28 2007, 06:31PM
The best and easiest way I have come across to ballast a MOT (or pretty much ANY 50/60Hz transformer for that matter) is by a minor and fairly simple rewiring of a variac so it ballasts the primary of your xformer. This allows you to adjust the amount of ballasting from nearly zero all the way to full current. The best part is, the output voltage (open circuit) stays the same all the way through the sweep. This is especially useful on HV transformers.
I'm sure just about anyone here can describe how to rewire one if you need help, that is, assuming you have a variac.
cbfull, Wed Mar 28 2007, 06:31PM
The best and easiest way I have come across to ballast a MOT (or pretty much ANY 50/60Hz transformer for that matter) is by a minor and fairly simple rewiring of a variac so it ballasts the primary of your xformer. This allows you to adjust the amount of ballasting from nearly zero all the way to full current. The best part is, the output voltage (open circuit) stays the same all the way through the sweep. This is especially useful on HV transformers.
I'm sure just about anyone here can describe how to rewire one if you need help, that is, assuming you have a variac.
Re: MOT ballast..
Part Scavenger, Wed Mar 28 2007, 07:31PM
It only needs ballast depending on what you are doing with it. Most people (on the cheap) use another MOT to ballast their other MOT's.
To convert the MOT into a ballast, connect one end of the secondary to the MOT's core (which is usually already done anyway) Then, connect the other end to the core as well. Voila! You have a ballast. Just put the primary of the ballast MOT in series with the MOT you are trying to ballast.
There is an article at my site under the articles section.
Click on "Current Limiting."
Part Scavenger, Wed Mar 28 2007, 07:31PM
It only needs ballast depending on what you are doing with it. Most people (on the cheap) use another MOT to ballast their other MOT's.
To convert the MOT into a ballast, connect one end of the secondary to the MOT's core (which is usually already done anyway) Then, connect the other end to the core as well. Voila! You have a ballast. Just put the primary of the ballast MOT in series with the MOT you are trying to ballast.
There is an article at my site under the articles section.
Click on "Current Limiting."Re: MOT ballast..
Myke, Thu Mar 29 2007, 02:00AM
I tried that an i figured that it will still draw too much current so sould i just use more MOTs?
Myke, Thu Mar 29 2007, 02:00AM
I tried that an i figured that it will still draw too much current so sould i just use more MOTs?
Re: MOT ballast..
Part Scavenger, Thu Mar 29 2007, 02:26AM
As a MOT or as a ballast? Adding another MOT in series will only increase the current. Adding another ballast will decrease the current.
Part Scavenger, Thu Mar 29 2007, 02:26AM
As a MOT or as a ballast? Adding another MOT in series will only increase the current. Adding another ballast will decrease the current.
Re: MOT ballast..
Nik, Thu Mar 29 2007, 03:45AM
^^ Adding anther mot (with the HV windings open) in series will result in a big drop in current (I've tried out of curiousity).
Nik, Thu Mar 29 2007, 03:45AM
^^ Adding anther mot (with the HV windings open) in series will result in a big drop in current (I've tried out of curiousity).
Re: MOT ballast..
Fusion, Thu Mar 29 2007, 09:31AM
I used a 100W lamp. It exist also 500W, if you sets 2 in parallel, you will limit to 1000W.
Fusion, Thu Mar 29 2007, 09:31AM
I used a 100W lamp. It exist also 500W, if you sets 2 in parallel, you will limit to 1000W.
Re: MOT ballast..
Zyrppa, Thu Mar 29 2007, 12:27PM
I can't get another MOT so i can't use it as ballast.
How about choke from fluorescent lamp ?If it can be used, it must be connect to primary winding, right?
cbfull, do you have schematic or something from that variac thing?
Zyrppa, Thu Mar 29 2007, 12:27PM
I can't get another MOT so i can't use it as ballast.
How about choke from fluorescent lamp ?If it can be used, it must be connect to primary winding, right?
cbfull, do you have schematic or something from that variac thing?
Re: MOT ballast..
Myke, Thu Mar 29 2007, 01:49PM
the socondary was not open.
before I used lamps but it was hard to get enough power and I wen up to about 900W woth it. I then used a hair drier instead and it was better.
Myke, Thu Mar 29 2007, 01:49PM
the socondary was not open.
before I used lamps but it was hard to get enough power and I wen up to about 900W woth it. I then used a hair drier instead and it was better.
Re: MOT ballast..
Zyrppa, Fri Mar 30 2007, 03:14PM
Do i connect hv ground(mot's core) to ground wire witch comes from power cord? Or do i left HV to "float"?
Zyrppa, Fri Mar 30 2007, 03:14PM
Do i connect hv ground(mot's core) to ground wire witch comes from power cord? Or do i left HV to "float"?
Re: MOT ballast..
sparky, Fri Mar 30 2007, 08:31PM
Resistive load - current limiting is not ideal. I'd use a 0.9uF 2200V rated MO capacitor. These are used as an inductive/capacitive load ~ also used for DC rectification to 4kVDC-5kVDC. MO caps are definitely the way to go.
MOTs are core grounded - so the green wire would attach to the MOT base - the high voltage comes from the secondary.
sparky, Fri Mar 30 2007, 08:31PM
Resistive load - current limiting is not ideal. I'd use a 0.9uF 2200V rated MO capacitor. These are used as an inductive/capacitive load ~ also used for DC rectification to 4kVDC-5kVDC. MO caps are definitely the way to go.
MOTs are core grounded - so the green wire would attach to the MOT base - the high voltage comes from the secondary.
Re: MOT ballast..
Myke, Sat Mar 31 2007, 01:53AM
I don't think you should connect the core to gnd cause it will increase the chance of getting zaped. just leave it floating.
Myke, Sat Mar 31 2007, 01:53AM
I don't think you should connect the core to gnd cause it will increase the chance of getting zaped. just leave it floating.
Re: MOT ballast..
ragnar, Sat Mar 31 2007, 05:21AM
I completely disagree, if you leave the core floating, it could become live. If you ground it properly, you'll not get shocks from touching it if the secondary arcs to it.
In this case, ground the core.
ragnar, Sat Mar 31 2007, 05:21AM
I completely disagree, if you leave the core floating, it could become live. If you ground it properly, you'll not get shocks from touching it if the secondary arcs to it.
In this case, ground the core.
Re: MOT ballast..
sparky, Sat Mar 31 2007, 08:33AM
ALWAY GROUND THE CORE!!
sparky, Sat Mar 31 2007, 08:33AM
ALWAY GROUND THE CORE!!
Re: MOT ballast..
Zyrppa, Sat Mar 31 2007, 01:26PM
Thank you. I just had to be sure about that.
Zyrppa, Sat Mar 31 2007, 01:26PM
Thank you. I just had to be sure about that.
Re: MOT ballast..
Steve Conner, Sat Mar 31 2007, 06:58PM
For goodness' sake. You shouldn't be touching any part of your power supply while you're running a coil. I prefer to ground MOT cores anyway, but not for safety reasons.
Steve Conner, Sat Mar 31 2007, 06:58PM
For goodness' sake. You shouldn't be touching any part of your power supply while you're running a coil. I prefer to ground MOT cores anyway, but not for safety reasons.
Re: MOT ballast..
Myke, Sat Mar 31 2007, 08:54PM
Ok sorry. I thought it would be safer not grounding the core. I'm not touching the HV output it is just that I thought if you brushed accidentally up against the HV you wont get zaped from being part of the ground or near the ground.
Myke, Sat Mar 31 2007, 08:54PM
Ok sorry. I thought it would be safer not grounding the core. I'm not touching the HV output it is just that I thought if you brushed accidentally up against the HV you wont get zaped from being part of the ground or near the ground.
Re: MOT ballast..
Michael W., Sun Apr 22 2007, 05:29PM
I think thats an EMI Filter, and If I'm right the answer is no, it won't ballast.....
Michael W., Sun Apr 22 2007, 05:29PM
I think thats an EMI Filter, and If I'm right the answer is no, it won't ballast.....
Re: MOT ballast..
HV Enthusiast, Sun Apr 22 2007, 06:15PM
With a MOT, i can almost certaintly guarantee that if you brush up accidentally to the HV output, it will kill you, or at the least cause you to stop breathing.
Don't even think of touching or going near a MOT while its operating.
HV Enthusiast, Sun Apr 22 2007, 06:15PM
Myke wrote ...
Ok sorry. I thought it would be safer not grounding the core. I'm not touching the HV output it is just that I thought if you brushed accidentally up against the HV you wont get zaped from being part of the ground or near the ground.
Ok sorry. I thought it would be safer not grounding the core. I'm not touching the HV output it is just that I thought if you brushed accidentally up against the HV you wont get zaped from being part of the ground or near the ground.
With a MOT, i can almost certaintly guarantee that if you brush up accidentally to the HV output, it will kill you, or at the least cause you to stop breathing.
Don't even think of touching or going near a MOT while its operating.
Re: MOT ballast..
kywalda, Sun Apr 22 2007, 06:37PM
I put some microwave-oven-caps in row as capacitive ballast. I had 4 mots to get 8600V at a power of 4KVA. So i limited the current to 0.47A what results to 18KOhm. So my caps had to be 0.17 uF ( C= 1 / (2 * pi * 50 Hz * 18 KOhm).
This could be realised with 6 microwave-caps (1uF at 2KV each) in a row.
But i was not happy with this. After a few seconds there were sparc-overs between the hv-coil and the core - even under oil 8-(
Now i'm using voltage-doubles with very good results.
kywalda, Sun Apr 22 2007, 06:37PM
I put some microwave-oven-caps in row as capacitive ballast. I had 4 mots to get 8600V at a power of 4KVA. So i limited the current to 0.47A what results to 18KOhm. So my caps had to be 0.17 uF ( C= 1 / (2 * pi * 50 Hz * 18 KOhm).
This could be realised with 6 microwave-caps (1uF at 2KV each) in a row.
But i was not happy with this. After a few seconds there were sparc-overs between the hv-coil and the core - even under oil 8-(
Now i'm using voltage-doubles with very good results.
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