Waytek sells the ATC fuses below that have either a manual or auto-reset
capability.

This offers some options to those deciding between circuit breakers or
fuses.

Link to the Waytek PDF catalog page:

http://order.waytekwire.com/IMAGES/M37/catalog/219_083.PDF


5-30 Amp, low-profile, manual reset (Type 1)

10-30 Amp, manual reset (Type 1)

10-30 Amp, auto-reset (Type 3)


5-30 Amp w push-to-trip test feature


Regards,
Chris Sargent

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of Bulent Aliev
Sent: Sunday, February 18, 2007 7:19 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: CBs and fuses

In my plane for everything electrical I installed, I asked myself:
can I fly without this item? And accordingly decided on CB or fuse.
A CZ builder had followed the plans and had installed the electric
nose gear fuse in the "per plans" location under the passenger seat.
He takes a passenger for a flight, but on retraction, his nose wheel
is cocked , hits the bottom of the fuselage and pops the fuse.
Something goes wrong with the manual override too. Now he asks the
passenger to unbuckle, turn around and put his butt against the
windshield, so he can replace the fuse while flying the plane at the
same time. If he had spent few dollars on a CB, he could have pushed
it in and flown with the gear down.
Buly
On Feb 18, 2007, at 7:35 AM, Thomas y Reina Jakits wrote:

Hi Al,

interesting!!

Next chance I have I will try to find out more about this
(reasoning for use of fuses over CB's in this helicopter).
I don't really buy the "repair after trip" -reason as the result is
the same.
Whatever caused the fuse or CB to trip, it should be repaired. What
really happens is that the fuse is replaced - if it doesn't trip
immediately, no one will look any deeper into it, than a
"look" (unfortunately...), .... until it trips again.
A lot of trips can be caused by changing environment (heat,
humidity, etc.) that bring the conditions for over current just to
the trip point, but will not under normal conditions.
However I am no specialist, not even building anything at this time
- so, I will try to find out for this specific application (AS350B3)

Thomas

PS: First thing I am going to do is to consult the Maintenance/
Repair manual....
----- Original Message -----
From: Al Gietzen
To: Rotary motors in aircraft
Sent: Saturday, February 17, 2007 6:10 PM
Subject: [FlyRotary] CBs and fuses


Eurocopter Factory Instructors are VERY COMPETENT in Eurocopter
Helicopter Systems!!

There is absolutely NO doubt that he knows the difference between
fuses and breakers and WHY either one would be used.


Thomas;

Certainly not impugning the competence of the flight instructors;
just suggesting the design engineers may have other reasons than
cost.  One may be reliability.  The reliability of CBs goes down
significantly after they have experienced a 'trip'.  I recall
reading one experts opinion that a CB should be replaced after a
'trip'.  Yeah; seems extreme.  The modern philosophy of circuit
design is to design for fault tolerance, so a fault; once causing
the protection device to open, is left for repair when you land.


The key for using fuses is fault tolerant circuit design and proper
selection and sizing of fuses.  Having done this; studies suggest
that the fuse offers higher reliability and lower cost.


There certainly reasons for either CBs or fuses, and I have both in
my plane.  For my flight critical circuits I opted for simple,
fault tolerance and fuses.  I wouldn't argue with someone making a
different choice.


FWIW,


Al

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