Re: Getting more input power

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

Original poster: Zagarus Rashkae <arbitrarily_random-at-yahoo-dot-com> 

Hi Ian,

Comments within...

 > Hi all,
 >
 > I have been talking to my electrician about getting
 > a 50A feed into my
 > workshop.
 > He has informed me that this is usually done with a
 > 3-phase connection.  I
 > should have pressed him for some more questions, but
 > forgot, so I'll ask the
 > knowledgeable people on this list.

Three-phase is great for DC coiling if you can get it,
and don't mind the extra cost of the rectifiers.

 >
 > My knowledge of 3-phase power is sketchy, whilst I
 > do understand the basics.
 >
 > If the outlet is rated at 50A 3-ph, then how much
 > power is available per
 > phase (to neutral) ?

Usually if it says it's 50A, it's 50A per phase
meaning a total of 3 * 50 * 240 = 36kVA, IIRC.

 >
 > If it is 1/3 of 50A that is OK, I could split the
 > power - use one phase for
 > the HV supply, and another for the RSG - but this
 > raises a major issue.  The
 > RSG will be out of phase with the HV supply by 120
 > or 240 degrees depending
 > on which two phases I use.  Is there any way of
 > adjusting this with some
 > sort of phase angle adjustment.  The JF phase
 > adjuster can only manage about
 > 90 degrees or so I believe.

For large adjustments of RSG phasing you can simply
rotate the motor in its cradle. Smaller adjustments
are best done with a phase adjuster while the TC is
running so you can look for best phasing.

 >
 > I wonder how my NST's would cope if I connected them
 > between phases ?  This
 > way they would be getting 415VAC, not 240VAC - and I
 > wonder if the
 > insulation in the tranformers could cope with the
 > higher voltage.  Anyone
 > tried this ?  My guess is .. no way .. we would be
 > upping a 15kV tranformer
 > to nearly 30kV, and we all know this is about the
 > dialectric strength of
 > air, and the first real problem point for insulation
 > breakdown and corona.

NSTs are pretty harshly abused in TC duty anyway and
it cannot take the extra stress! Nearly dobling its
rated output voltage will certainly kill it quickly.

 >
 > Rgs
 > Ian
 >
 >

Regards,

Chris Lu