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                           AeroElectric-List Digest Archive
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                     Total Messages Posted Sat 01/14/17: 1
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Today's Message Index:
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     1. 03:31 PM - B-lead protection and other things  (Robert L. Nuckolls, III)
 
 
 
________________________________  Message 1  _____________________________________


Time: 03:31:14 PM PST US
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Subject: AeroElectric-List: B-lead protection and other things

If you look at my schematic, the current shunt is located near the 
alternator.  If the 60 Amp circuit breaker is pulled, the 2 amp and 5 
amp field breaker is closed.  What will the voltage be at the 
alternator output?

    Very high . . .

With the open 60 Amp breaker, the regulator has no feedback or sense 
of the alternator voltage.  Does the field go "full on" and the 
alternator voltage goes to max output?  If so, what is this 
output.  The voltage at the shunt is directly connected to the Dynon 
Skyview Engine monitor.  If this goes above 30 Volts than this will 
explain the damage to the Engine Monitor Module.

    It's not that simple. Most instrumentation
    INPUTS are not particularly vulnerable to
    higher than normal voltages . . . but check
    with Dynon on this.

    I don't recommend circuit breakers in the
    alternator B-lead . . . haven't illustrated
    such a device in that location for longer than
    I can recall.  Please take your b-lead to the
    HOT side of the starter contactor. Mount a mini-anl
    CURRENT  limiter next to the starter contactor
    to protect the b-lead wire.

http://tinyurl.com/hudpg2g

    You can buy a 'stock' mini-anl mounting
    block . . . or make your own from a piece
    of durable, insulating material. Phenolic,
    delrin, etc.

http://tinyurl.com/h9ze97d

    If you use a purchased mount similar to
    that described above, remove and throw away
    the 'set screws' provided to grip your
    fat wires. Install REAL terminals on the
    fat wires and bring them directly into
    contact with the ANL tabs by having them
    SHARE the same fastener.

    Circuit breakers on alternator b-leads
    was never an elegant idea . . . and if
    opened accidently or due to nuisance trip
    . . . the outcome can be unhappy.


I plan on installing a 18V MOV on each of the shunt sense lines to 
ground.  This will short out to ground if the alternator output 
exceeds 18VDC and blow the two 1 amp fuses (not shown) to protect the 
Dynon Circuits.

    MOV's are also not a good idea . . . I
    got suckered into considering them early
    on based purely on their spec sheets. As
    it turns out, the transorb is 100X more
    suited to this task. Use at least 1500W
    rated devices.

http://tinyurl.com/hjoc5aw


   Bob . . . 

 

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