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Date: Mon, 09 May 2005 13:57:22 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: EC2 redundancy
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Wendell Voto wrote:

>----- Original Message -----
>From: "WALTER B KERR" <jbker@juno.com>
>To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
>Sent: Monday, May 09, 2005 8:23 AM
>Subject: [FlyRotary] Re: EC2 redundancy
>
>
>  
>
>>Jim S wrote:If we've mostly agreed that we're sizing fuse/CB to protect
>>the wire and
>>not the component, what would be the point of redundant feeds to a
>>common power line inside the box?
>>What failure mode are we protecting against with this scheme? ... Jim S.
>> -----------------------------------------------------
>>
>>We are protecting against a defective fuse such as Paul had or a direct
>>short in one of the lines that has blown a good fuse. The other line will
>>continue to operate the EC2 if you have diodes to prevent a backfeed. Of
>>course you wish to separate the wires to prevent the burning one from
>>destroying the 2nd one.
>>
>>Bernie
>>
>>    
>>
>If one line is shorted and they are tied together in the box, then both
>lines - fuses or breakers - will see the short fault and trip.
>
>Wendell
>
>
>  
>

Or worse.  Both fuses/breakers see the fault and together they're strong 
enough to overcome it.  A single 10A fuse blows after little spark in 
the open end of the cracked wire insulation.  No problem.  But what 
happens when you provide the 'arc welder' some backup.

-- 
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