Re: Balast (was Re: to Bert Hickman)
Sent: Wednesday, July 30, 1997 6:22 AM
Subject: Re: Balast (was Re: to Bert Hickman)
In a message dated 97-07-28 13:56:54 EDT, you write:
From: Julian Green[SMTP:julian-at-kbss.bt.co.uk]
Sent: Monday, July 28, 1997 12:45 PM
Subject: Balast (was Re: to Bert Hickman)
Balast is something that I have been trying to get sence I got my
pole pig, but as yet have not been successfull.
I recently salvaged a 25KVA welder from a heap of scrap metal but
not connected it up as my coil seems to run perfectly well without
it. It also need some fixing.
I put this down to the spark gap which is a high speed rotary with
the minimum number of electrodes (2) on the rotor. The rotary runs
at about 300 BPS.
The wall socket power is 13A -at- 240v and output spark length is 45"
(need bigger garage) nice white hot - burns holes through wood.
Coil stats are: 7" x 21" Secondary 770 turns, 24" x 5" toroid, 21"
primary, 0.03uF cap. Primary voltage 11KV.
Tuning a coil without balast is tricky as violent current spikes can
occur, but these can be kept at a minimum if the speed of the rotary
is kept high.
When good tuning is achieved the power from the wall socket drops,
the intencity of the spark gap drops and output spark length increases.
Do other coilers believe that adding inductive balast would increase
the output spark, or do I have a spark gap that solves the balast
Please comment on this as I would like to know if my coil is any good.
Your coil sounds like a nice system. If you are using a pole pig and no
inductive or resistive ballast, the current limiting must indeed be due to
the rotary. 13 amps of primary current is only about 3kva. If you want
increased performance, you need to increase the input power level. This will
probably require more rotor contacts and then some inductive ballast. Since
you have the welder, I would sure try it. I would also try to increase the
voltage from 11 kv up to 12 or 15 kv if possible. Does your variac have a
higher voltage output that you can select?
My 5kva pole pig will draw 10 to 45 amps depending on where I have the welder
I would think your system should be capable of 5 to 6 foot sparks.