Paul,
Further to the previous answers, there are two principal reasons for having
a switch between the alternator output and the bus bar: first, to enable the
bus bar to be isolated from the alternator in the event of an electrical
emergency (if smoke came out of the wires, switching off the battery master
would still leave the alternator feeding the bus as long as the engine was
running); second, having followed the Rotax recommendation to feed one
electrical pump for the 914 directly from the alternator, the bus isolation
switch avoids that pump running from the battery whenever the battery master
switch is on with the engine stopped (e.g. if you wish to set up way points
on your GPS before starting).
The reason for having a slow-blow fuse is to avoid nuisance trips caused by
current surges. This requirement can be satisfied with a standard (as
opposed to a "fast-acting") fuse. However, if you are planning to
incorporate overvoltage protection you will need a circuit breaker and an
alternator relay rather than a fuse to follow Bob Nuckolls' advice (see the
Air Electric Connection circuit Z 7 designed for permanent-magnet
alternators such as on Rotax 912/914).
Mike
Europa Club Safety Officer
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com]On Behalf Of Paul McAllister
Subject: Europa-List: Electrical questions
<paul.mcallister@qia.net>
Hi all,
I am at that interesting stage (not sanding & filling). I have a couple of
questions.
1. The Rotax engine monitor shows a double pole switch that is for
disabling the waste gate servo. Why would I want this, has anyone fitted
this ?
2. The Europa manual shows a 25 amp switch for between the alternator
output and the main buss. I intend to install an OVP so I don't see the
need for an additional switch, am I missing something here.
3. Last question, what have folks been using for 30 amp slow blow fuses.
The only thing I have come across is fusible links the Bob Nuckles uses
which I don't particularly care for.
My current thinking is an E-Buss feed arrangement with an auxiliary battery,
but to still feed one fuel pump (914) directly from the alternator output as
described in the Europa & Rotax manuals.
I welcome any comments.
Thanks, Paul
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