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Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Hi all, I can buy 2 MOTs and 2 microwave caps from a friend (yes I have to buy them cause it's nearly impossible to get them here), I thought of connecting the MOTs in series and the 2 seriesed caps in series with the MOTs' output.
Do you think this will provide enough current limiting? From my calculations the short-circuit current should be ~700mA but that's assuming the output voltage stays ~2200VAC per MOT.
Has anyone tried this? I'm mainly worried about the caps resonating with the MOT secondaries, increasing the current even more. If the caps dont provide enough limiting I wont buy the MOTs cause I have no other way to limit the current.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
You can limit it easily by doubler (or singler - that's doubler but one of the caps is left open). But of course you get pulsed DC and you need two HV diodes...
Registered Member #1127
Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139
MOT trannies are already A. shunted B. the caps provided provide plenty of inductive action to cause a lessening of the output current.
- a typical 700-800 watt MOT will pull 13-15 A when shorted. A 1000-1200 watt MOT will pull 25A when shorted typically.
YEP. I have a dual MOT stack that runs 2 1100 watt MOT units in series - with 1 uF 2500V capacitors and a voltage tripler supply - running 16 kVDC. I use a 240V 30A breaker - and typically I draw about 22A during load operation.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
MOT_man wrote ...
B. the caps provided provide plenty of inductive action to cause a lessening of the output current.
I don't know what you mean by "caps provide inductive action", I thought they provide capacitive action but anyways, are you telling the capacitive limiting will work well?
Registered Member #1127
Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139
Yep... rolled capacitors have a specific amount of induction - this helps a bit- and the uF rating alone allows for a specific amount of current to be pulled through them too. You should be okay using MOT caps to ballast your beast.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
NeilThomas wrote ...
Do you think this will provide enough current limiting?
enough current limiting for what? Cap charger, TC, Jacob's, other?
For a Jacob's ladder or just simple arc fun.
I told my friend who has many MOTs and caps if he could try it, he tried with 2 series MOTs and 4 caps in series-parallel configuration. He sent me a video- the arc was HUGE!! And it didnt trip the 15A breaker. So I guess that if I go with just 2 series caps it will work too, just with smaller arcs.
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Ok just to tell everyone that I have the answer - 2 series MOTs with 2 series caps will pull just a little arc, but with 4 caps series-parallel the arc is very big (longer than without the caps) and looks really deadly
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MOT current limiting
but anyways, are you telling the capacitive limiting will work well?
