Re: Capacitors for MOT ballasting AND shorted turn .

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "colin.heath4 by way of Terry Fritz <teslalist-at-qwest-dot-net>" <colin.heath4-at-ntlworld-dot-com>

hi justin,
             th9is is the main problem with secondary side ballasting. the
best way to protect is a breaker and also a fuse as there are horror storys
of breakers welding shut under high fault currents
cheers
colin

----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, April 02, 2003 2:27 AM
Subject: RE: Capacitors for MOT ballasting AND shorted turn .


 > Original poster: "Justin Wright by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <justin-at-tracesofnut-dot-com>
 >
 > Hi All,
 >
 > I have a large pair of 6kv transformers that I had in series for 12kv.
 > And by the look of the primary coils, they definitely need ballasting.
 >
 > I used a spreadsheet to roughly calculate the primary current by varying
 > the number of MOT caps on the secondary side.  When I measured the
 > primary current I was surprised to find that the results matched the
 > calculations quite well.
 >
 > I could vary the current draw accurately by adding or removing caps.
 >
 > BUT...
 >
 > 1). I noticed a little bit arcing between the capacitors cases.
 >
 > 2). One of my transformers developed a shorted turn.  Since the
 > ballasting was no longer in effect, the current draw increased to an
 > alarming (scary) level.
 >
 > I guess this isn't a common occurrence and the circuit breakers should
 > protect everything, but I still worry about using capacitive ballast on
 > the secondary side.
 >
 >
 > Justin.
 >
 >
 >
 >
 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Wednesday, 2 April 2003 4:52 AM
 > To: tesla-at-pupman-dot-com
 > Subject: Re: Capacitors for MOT ballasting . . .
 >
 > Original poster: "tesla by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <tesla-at-paradise-dot-net.nz>
 >
 >   >
 >   > I've also seen microwave oven capacitors used for ballasting (usually
 > placed
 >   > in series with the MOT supplies) and to correct phasing problems . .
 > . any
 >   > comments on this ???
 > Greetings Dan et al
 >
 > This idea has intrigued me for some time.
 >
 > As the O/P Z of the MOT's will be equivalent to a voltage source with a
 > largish series inductance placing caps in series must have the
 > possbility of
 > increasing the O/P current by cancelling out the limiting inductive
 > reactance.
 > This occured in my set up which had some mains side inductive
 > ballasting.
 > When I fed the beast into a large capacitive load the mains current shot
 > up
 > a lot.
 >
 > This may have been because of my additional inductive ballasting but it
 > suggests to me that care in selecting the capacitive reactance should be
 > considered.
 >
 > Hope to hear from others on this issue
 > Best
 > Ted L in NZ
 >
 >
 >