Rowland,
Just a quick thought over about 10 panel installations:
I use a perihelion design OVP which is a fancy resettable crowbar (see
periheliondesign.com) It kills the control circuit (C terminal) in the
Rotax or the field in a standard internally regulated external
alternator ending the power. It can be hooked to a relay to kill the
feed leaving the regulator to run away if you so choose. Perhaps still
powering some non overvoltage critical items.
You can use the somewhat crude but effective Knuckolls crow bar to kill
a relay and allow a double pole relay to light a light bulb on the
panel. When the relay opens, the contact from the panel side could
light a light. I suggest an in line fuse to prevent full bus voltage
---From being unprotected. Eric Jones at Perihelion Design has done this
for us in the US but his gear may not be permitted in the UK.
As for the alternator light, it is basically the most worthless tool in
the shed (in my opinion)
It only lights if the regulator is working properly and the alternator
does not produce current. Engine off/battery and alternator switch on.
It operates on the concept of comparing the control voltage to the
output voltage. As the alternator sits quiet at engine off, the light
gets power from the control through the battery of course. The bulb
lights up (note that the alternator must be a light bulb and not an LED
as current goes two ways) as the L or light side of the regulator is
essentially grounded. As the alternator begins to produce power, the
voltage of the output equals the control voltage and the light
extinguishes as it has +12 on each side (slightly less as diodes are
involved) and the bulb is out.
Should your regulator fail, the light is inop. If only one or two
diodes of the triple diode rectifier fail, the light may dimly light as
the alternator is in an under voltage condition. I have seen this only
one time in my whole life. Normally your first indication of a failure
of your regulator is your low battery warning light if you have one.
That is why I preach that one must have an ammeter and voltmeter to
determine his electrical systems health.
Now if the alternator circuit has high resistance going from the bus to
the C terminal or otherwise is running below bus voltage, the voltage
regulator will cause an overvoltage condition, completely undetected
unless you have an OVP circuit. Knuckolls came up with a handy kill
mechanism to protect the circuitry. Just not very elegant.
This is why I went to the Eric Jones/Perihelion Design unit. It costs
about $100 with shipping and is worth every penny. One LED and one
reset button (though I wouldn't reset and overvoltage condition
normally).
Best Regards,
Bud Yerly
Europa Tech Support
Custom Flight Creations, Inc.
www.customflightcreations.com<http://www.customflightcreations.com/>
(813) 653-4989
----- Original Message -----
From: Rowland Carson<mailto:rowlandcarson@gmail.com>
To: Europa e-mail list list<mailto:europa-list@matronics.com>
Sent: Monday, August 13, 2012 3:31 PM
Subject: Europa-List: crowbar component location for rotax
installation
<rowlandcarson@gmail.com<mailto:rowlandcarson@gmail.com>>
I'm checking through various parts of my circuit diagram and after
looking at the crowbar circuit (for the Rotax integrated alternator -
LAA mod 10404, issue 5, Jul 2003) I have a query.
How does one know when the crowbar has operated?
Would it be a good idea to put a warning lamp across the 5A breaker to
show when it has popped?
It seems OK to me (as a disciple of Bob Nuckolls) to have the whole
crowbar circuit close to the alternator, in the engine compartment and
thus the 5A breaker not accessible in flight. But I'd like to have some
positive indication if it ever has to do its job.
Any thoughts or prior art?
in friendship
Rowland
| Rowland Carson ... that's Rowland with a 'w' ...
| <rowlandcarson@gmail.com<mailto:rowlandcarson@gmail.com>>
http://www.rowlandcarson.org.uk<http://www.rowlandcarson.org.uk/>
| Skype, Twitter: rowland_carson Facebook: Rowland Carson
| pictures:
http://picasaweb.google.com/rowlandcarson<http://picasaweb.google.com/row
landcarson>
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
|