Ferg,
The Rotax Installation Manual has the values and charts. It is para
19.5 in my Rotax installation manual. The new Europa manual has the
diagram in chapter 25.
Typically the max the 914 will draw is 3 amps per pump at max pressure
and 2 min under light pressure load. The rest of the system draws about
1.3 for the servo and computer and .5 for the warning lamps.
As for wire size, #18 is the min size I'd do. The Europa manual shows
the pumps using a #20, and that will do amperage wise, but you will
notice the wire temperature rise a few degrees, although the voltage
drop is minor. #18 will supply 6 amps (double what you need) with only
10 degrees C rise in temp and .06 ohms per foot. That is enough safety
factor and a lower voltage drop for consistent operations at 3 amps.
Besides, my Amp ring connectors fit better. Pumps should be planned to
run constantly, and with a minimum drop of voltage at max load, and #18
can do it.
Remember the ground needs to be the same size, and I suggest separate
grounds per pump to ensure redundancy.
Rotax wants you to run the aux pump off the alternator direct for
redundancy but I have yet to do it. My wife liked the idea of running
mine off a separate battery (charged through a shotkey diode) to back up
full electrical failure. (Yea, she really hates the idea of the whirly
thing stopping up front.)
Happy new year.
Bud Yerly
Custom Flight Creations
----- Original Message -----
From: Fergus Kyle<mailto:VE3LVO@rac.ca>
To: EUROPALIST<mailto:europa-list@matronics.com>
Sent: Thursday, December 27, 2007 10:22 AM
Subject: Europa-List: Fuel pumps
<VE3LVO@rac.ca<mailto:VE3LVO@rac.ca>>
Happy Christmas and New Year greetings...
Perhaps it's my advancing lack of thoroughness, but can't find the
magic electrical current values for the Rotax 914 pumps. Somewhere in
the
dim past I calculated 15 feet of feed needs #18 wire because I
measured 1.2A
when testing the output before installation. However it occurs to me
that
perhaps the pumps demand more when under load and I haven't allowed
for
that.
What's the consensus - or - where do I find the figures?
Cheers
Ferg
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