Mot Stack-Current limiting / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Mot Stack-Current limiting

previous 1 2 3 next

Move Thread

LAN_403

radiotech

Tue Jul 27 2010, 08:20AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

A lightbulb has resistance that changes depending on how bright it is. A dim bulb has less resistance than a bright one.

Annoyingly, a tungsten lightbulb also acts like capacitor with a leading current. This obscure fact is only valid for bar bets, since the proof lies in a 100 year old paper. Light switches are "T" rated to show wont weld closed on the inrush current.

Dr. Dark Current

Tue Jul 27 2010, 08:58AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

or you can use HID lamp (mercury vapor etc.) ballast chokes to limit the current, a resistive ballast from lightbulbs usually doesn't work very well "arc wise".

But I think the best for you would be to make an inductor from your secondary-less MOT...

Micha0_0

Tue Jul 27 2010, 11:25AM

Registered Member #2990 Joined: Mon Jul 12 2010, 11:22AM
Location:
Posts: 40

Dr. Kilovolt wrote ...

But I think the best for you would be to make an inductor from your secondary-less MOT...

if i donÂ´t have to kill it ,because i would use it also for high current experiments ;)

in a few minutes iÂ´ll test my selfmade ring-core-ballast, i hope 1,5mmÂ² wire is not too less for that power
(it is wound with 104 turns/18metres of 1,5mmÂ² speeker wire)

Micha0_0

Tue Jul 27 2010, 01:42PM

Registered Member #2990 Joined: Mon Jul 12 2010, 11:22AM
Location:
Posts: 40

now i tested the ring-core,but i think it is too less limited,because with 104 turns i can arc about 30 seconds
after the 30 seconds arcing the wire around the core is very warm but not hot!

i testet the lightbulb in series to the ring-core,but this didnÂ´t work (the light bulb lights but the mots didnÂ´t work)

iÂ´ll make some more turns on my ring-core

hereÂ´s a pic from it

TRe7tettEZ T

Micha0_0

Tue Jul 27 2010, 03:05PM

Registered Member #2990 Joined: Mon Jul 12 2010, 11:22AM
Location:
Posts: 40

so now iÂ´ve a new problem ...

i wound again some turns on the core ,i made 117,but the stack does again just a 5mm spark

the i tested it always with 3turns less...bis always the samen effect...

the core was warm again
then i put off all the new turns so it has 104 turns left.
but now also with the 104 turns it makes just a 5mm spark.

then the core was a little bit hot and i thougt the mot could be broken
so i touched it an it was f*kin hot (you just can touch it 1-2 seconds)

at least i tested it completely without any ballast and the circuit braker switched the electricity off

what iÂ´ve made wrong now ?
iÂ´m really frustrated :D

Dr. Dark Current

Tue Jul 27 2010, 05:46PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

If the secondaries are in parallel, maybe you wired the transformers out of phase and they run into a short-circuit.

Micha0_0

Tue Jul 27 2010, 08:52PM

Registered Member #2990 Joined: Mon Jul 12 2010, 11:22AM
Location:
Posts: 40

if thery would run in a short circuit there woudnÂ´t be that 5mm spark

i dont know if they are in paralell or not...because my mots are stupid...

if i put them im series (secondary)
HV output(mot1) to Core(mot2)
an HV output (mot2) is arcing to core(mot)1
am i right ?

but it doesnt work

i tested it antiparalell...just a 5mm spark
Core(mot1) to Core(mot2) to gnd
HV(mot1) arcs to HV (mot 2)

now i have an complete other wireing
Core(mot1) to core(mot2) to gnd
HV(mot1) to gnd
HV(mot2) arcs to core(1&2)

and itÂ´s not just 1 mot or 2 paralell because before my problem i got 10-15cm arcs an one mot just gives 5-7 cm arcs

Dr. Dark Current

Tue Jul 27 2010, 09:00PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

wrote ...
i tested it antiparalell...just a 5mm spark
Core(mot1) to Core(mot2) to gnd
HV(mot1) arcs to HV (mot 2)

If you want to run them "antiseries", then you basically got that right just the MOTs are phased wrong, swap the connections to one of the primary windings.

PS. series connection gives the longest arcs.

radiotech

Tue Jul 27 2010, 10:04PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

What is the ringcore made of? It looks like ferrite about 6 cm diameter. I dont think it can do much with 2000 amp/turns. Suggest you use use iron core stack of laminations. with about 4 .5 cm^2 centerleg with 100 turns.

lpfthings

Wed Jul 28 2010, 06:49AM

Registered Member #1361 Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305

Not to mention ferrite isn't the best material for low frequency mains work, ideally you'd need an iron core.

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob