From: "Al Gietzen" <ALVentures@cox.net>
Date: 2004/06/07 Mon AM 11:52:28 EDT
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: LS1 Coils - amp draw?

Tracy;

Well; the worry is this.  Safe wiring practice requires being able to
protect the wire, especially if it is in a bundle or close proximity with
other wires, against any failure which would overload the wire.  Running the
numbers says that the maximum safe current for a 16 awg wire is 15 amps.  If
I interpret you correctly; it is possible for my coil power lead to have to
carry 27 amps (for 3 coils) for a short time, which would trip a breaker, or
blow a fuse.  Under these conditions one can not properly protect the wire
against a potential short - unless a much larger wire is used.  My wires run
in a wiring duct, which isn't exactly a bundle, but the analysis says for 27
amps in a bundle you need about a #10 wire.

Further; I went to great lengths to maintain the redundancy that you also
strived for in the ECU with the dual controllers and the isolation switches.
I have the engine critical bus connected to the dual battery system, and
isolated by 40 amp diodes.  I think you're suggesting that it's possible for
the coils to momentarily draw 54 amps (6 x 9), plus pump and injectors;
maybe up to nearly 70 amps.  Ain't gonna work.

So what am I misunderstanding here, or how do we get around this?  Under
what temporary condition can this high current exist?  Is there an
operational sequence to avoid this possible condition?