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Subject: Re: TWL: Electrical Problem
From: Arild Jensen (elnav@XXX.XXX)
Date: Sat Feb 02 2002 - 17:09:25 EST
At 07:42 AM 02/02/2002 EST, Rollsdoc@XXX.XXX wrote:
>Did you say the invertoer and gen set were not grounded? They should be.
They
>both should have green wires bonding them to the boat at all times.
>Rodger Wrona
REPLY
Not the same thing!
In the case of the touch switch the body capacitance works against the
ground plane.
Most often the trigger circuit is something called a blocking oscillator.
The body capacitance loads the free running oscillator circuit by
interacting with a part of the cirucit which in effect acts as a
radiating antenna. The ground plane of the earth is apart of this circuit.
and the person's body afffects this by grounding the osc. into the earth.
When the oscillator stops running, a semiconductor switch toggles on or
off to suit.
National semiconductors ( among others ) makes such a chip for industrial
and comsumer product applications.
For a detailed technical description refer to their application text books.
You do not have the same relationship to ground in a boat as you do ashore
because the system is floating with a single round point. he popular
duplex test plugs will often get confused when testing outlets aboard
a vessel running on a genset or inverter due to the changed relationship
of ground, neutral and hot lines.
More than once I have seen them give faulty test results with inverters
or gensets while testing correctly when shorepower is used in the same
boat and testing the same outlet.
Cheers
Ariild
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