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Re: Large Transformer Question (fwd)
---------- Forwarded message ----------
Date: Sat, 14 Feb 1998 16:47:18 -0800 (PST)
From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
To: tesla-at-pupman-dot-com
Subject: Re: Large Transformer Question (fwd)
"Tank cap size is a function of the transformer's output voltage and the
operating frequency. The higher the output voltage, the larger the
current capability needed. A rule of thumb is about 0.01 uF for every 60
mA off a 15 kV transformer. For example, the following table can be used
for approximate sizing:
uF uF
Max -at- Max -at-
kV mA 60 Hz 50 Hz
== == ===== =====
9 30 0.008 0.011
9 60 0.018 0.021
12 30 0.007 0.008
12 60 0.013 0.016
15 30 0.005 0.006
15 60 0.011 0.013
The table can be scaled for larger current values as appropriate."
These values of capacitance will (approximately) result
in series resonance of the secondary, and failure due to voltage
breakdown and/or overheating if you operate without a safety
gap. Larger values of capacitance will, of course, work OK but
there is a limit to what should be done. Will publish some
pictures of simulated secondary waveforms where the transformer
is modeled as a voltage source in series with the leakage reactance
and the spark gap is modeled as a voltage controlled switch.
Ed