Re: joules confusion sort of

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi Luke,

The true enery per bang will be 1/2 * CV^2.  The 900/120 estimate assumes a
power factor of 1.0 and a Cp that results in 120 BPS.  The 15KV * 60ma is
the VA rating of the NST and calling it a 900 watt transformer is probably a
misnomer.  The actual power from the NST will be power = VA * power factor.
The power factor (and I'm not talking about PF correction) is dependent on
the type of spark gap (static vs sync rotary).  I think one needs to think
(in the context of static gaps) of a PF of ~0.5.  Static gaps can not take
advantage of the energy stored in the inductance of the NST (aka inductive
kick) like SRSG's can.  Note that 1.6 * Cres with a static gap gives about
120 BPS.  With a SRSG at 120 BPS (called pps as in presentations per secend)
and timed right, a Cp of 3.2 * Cres can be almost fully charged (hence
approximately 900 watts are can be processed.

Gerry R

 > Original poster: "Luke" <Bluu-at-cox-dot-net>
 >
 > When talking about a 900 watt NST (15KV 60mA) operating into a 120BPS
 > static gap the joules has been said to be 7.5 per bang.
 > 900 / 120 = 7.5
 > this makes sense to me since the 900 joules in one second will be
displaced
 > over 120 pulses.
 >
 > but the cap size seems to dictate other wise.
 > A cap with a value of 0.016 mfd and a peak charge voltage of 21.2KV would
 > only have 3.6 joules
 > 0.000000016 * 0.5 * 21200^2 = 3.59552
 >
 > I am assuming the static gap would be running at 120bps for this.
 >
 > Even if a rotary gap were used and a cap size of 0.028 mfd were used the
 > joules would be 6.29
 > That isn't even up to the 7.5 joules used by some for calculation.  Lets
 > not go there on the rotary for the answers yet.  J don't want to confuse
 > myself.  Only pointing out that that doesn't equate either.
 >
 > Is there something I am missing?
 > Why do some use the 7.5 joules when the cap size would not let it store
 > that much energy any way?
 >
 > Any insights on this?
 >
 > Luke Galyan
 > Bluu-at-cox-dot-net
 >
 >
 >