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From: "Joe Ewen" <jewen@comporium.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1845948@logan.com>
Subject: Re: [FlyRotary] ATC fuses with manual or auto-reset
Date: Sun, 18 Feb 2007 22:45:57 -0500
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Waytek carries Type 1 and Type 3.  There is another type I have found 
useful, Type 2.  Type 1 will reset as soon as it cools down, so if the 
overload still exists it will, reset, blow, reset ...    Type 2 has a small 
resister so that when it blows only a small current will flow but it is 
enough to keep the breaker tripped and hopefully not stress the protected 
device further.  On critical items such as injectors, ignition coils, ec2 
etc, I have used type 1.  On equipment I do not want to have turn back on 
without intervention I have used Type 2.  The Type 3 (manual reset) is nice, 
but in my application, they are not accessible in flight, since they do not 
panel mount.

All these breakers are made by Bussman, their part numbers are CB221-x (Type 
1, auto reset), CB222-x (Type 2, modified reset), CB223-x (Type 3, manual 
reset).  The Type 1 and Type 2 breakers as well as an assortment of ATC fuse 
blocks are available from   http://delcity.net/

In applications where I wanted lower ampacity protection than the minimum 10 
Amp breaker (such as avionics, computer, touch screens, and IO), I removed 
the bimetallic from a CB221 and soldered an appropriately sized PTC in its 
place.  The package then fits nicely into a ATC fuseblock.

Joe


----- Original Message ----- 
From: "Chris Sargent" <rv7rotary@knology.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, February 18, 2007 6:57 PM
Subject: [FlyRotary] ATC fuses with manual or auto-reset


>
> 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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