[TheForge] Re: Generators

[Paul Sperbeck]

On the contrary, the voltage is highly relevant. Although the amount of
current required to cause a disruption in the heart muscle for example is
relatively low, see the following table or the reference at:
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html


BODILY EFFECT     DIRECT CURRENT (DC)    60 Hz AC     10 kHz AC
---------------------------------------------------------------
Slight sensation     Men = 1.0 mA         0.4 mA        7 mA
felt at hand(s)    Women = 0.6 mA         0.3 mA        5 mA
---------------------------------------------------------------
Threshold of         Men = 5.2 mA         1.1 mA       12 mA
perception         Women = 3.5 mA         0.7 mA        8 mA
---------------------------------------------------------------
Painful, but          Men = 62 mA           9 mA       55 mA
voluntary muscle    Women = 41 mA           6 mA       37 mA
control maintained
---------------------------------------------------------------
Painful, unable       Men = 76 mA          16 mA       75 mA
to let go of wires  Women = 51 mA        10.5 mA       50 mA
---------------------------------------------------------------
Severe pain,          Men = 90 mA          23 mA       94 mA
difficulty          Women = 60 mA          15 mA       63 mA
breathing
---------------------------------------------------------------
Possible heart        Men = 500 mA        100 mA
fibrillation        Women = 500 mA        100 mA
after 3 seconds
---------------------------------------------------------------
The upshot of all this is that if the voltage is low, and you cannot
consider physical effects without considering both voltage and resistance
which determine the current flow, insufficient current will flow to cause
serious harm. That was the reason for the high voltage comment regarding the
capacitors. The voltage was a flippant value, but would probably be
sufficient to cause harm. The voltage is not irrelevant, the voltage and the
capacitance also determine how many watt-seconds are available for 'use'.
Unlike batteries, whose large internal resistance relative to capacitors,
limits the peak current flow, the lower internal resistance of large power
capacitors will yield much larger peak currents relative to a battery.

Harking back to the generator question that began all this, zapping the
field winding with a large current pulse will magnetize the core of the
field magnets. How permanent that effect is depends on the steel. The
armature core is the object of the magnetic fields that are created in the
field windings, and the induced magnetic field in conjunction with the
armature windings is the where the power is drawn off by the load circuit.
The armature cores are not designed to retain magnetism and in many cases
the field winding are either externally powered to provide control over the
output voltage, as in your cars alternator, or the fields are comprised of
permanent magnets. In the book, Alternator Secrets, available from Norm
Larson I believe, their is an example of an electric motor used as a
alternator. In this book the author speaks to possibly zapping one of the
windings to generate a residual magnetic field until the unit begins
generating power, whereupon the unit would self-excite...


-----Original Message-----.
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net]On Behalf Of Andy Vida
Sent: Wednesday, September 01, 2004 11:06 AM
To: Sponsored by ABANA
Subject: Re: [TheForge] Re: Generators

Paul Sperbeck wrote:
>
> Hi guys...
> Just a note to the note...
> 30,000 mfd is .03 farad.
> mfd stands for microfarad, each unit of which is one millionth of a farad.
> Don't get me wrong though, 30,000 mfd at 300 to 400 volts will send you
into
> the next plane of existence...

	I think that the voltage is irrelevant.  That much current at
	any voltage will cook you.  1 Farad is a LOT of electrons.

Paul C. Sperbeck

My Grandfather was a blacksmith,
and It didn't do me one damn bit of good...
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