[TCML] Nevada Lightning Laboratory on Wikipedia
lod at pacbell.net
Thu Jan 6 22:06:42 MST 2011
More on the Lorentz Force can be seen here:
The NLL will require a primary switch array capable of switching 40kV at
50kA. The switch array will consist of hundreds of custom IGBT sections
in a series-parallel arrangement. Our bench rig for developing and
testing the high current IGBT sections consists of a water-cooled tank
circuit, sintered metal resistors and a 3-phase cap charging supply.
The tank circuit inductor, capacitor and resistor values reproduce the
frequency, voltage, peak current and ringdown Q that each IGBT section
will experience in the full-scale NLL system, at full power.
Each time the IGBT section fires, the Lorentz forces work to compress
the conductors, and expand the diameter of the tank inductor. This
produces a notable sound from the conductors, very much like someone
‘pinging’ the copper pipes with a metal wrench. Since the operating
resonant frequency is about 5200Hz, the Lorentz forces are probably
exciting various mechanical resonances in the copper conductors. Some
sections of the circuit are plumbed with wide, thin copper sheet, which
visibly move during each pulse as well.
I actually consider it a useful feature that the circuit provides a
pleasant pinging sound when the IGBTs are firing. GL
> Date: Wed, 5 Jan 2011 15:59:57 +0100
> From: "Teslalabor" <teslalabor at t-online.de>
> Subject: Re: [TCML] Nevada Lightning Laboratory on Wikipedia
>> > The Lorentz forces produce a pleasing ping note from the copper
>> > conductors.
> This sounds amazing!!! Could you explain this a little bit more in detail?
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