The small wire goes to its separate circuit breaker. The crowbar is connected to this wire (and ground).
When the crowbar circuit senses an over-voltage, it clamps that wire to ground (and pops the circuit breaker).
Only works on your kind of alternator that stops putting out voltage on the fat wire when it doesn't get voltage in on the "thin" wire. As someone else asked, does it really stop putting out voltage on the fat wire - easily measured on the fat wire with a voltmeter - voltage should drop to maybe 13.2 V as opposed to the 15 - 16 Volts when alternator is delivering power.

Finn

WALTER B KERR wrote:

 Are you saying that you are running an internally regulated, 
'one-wire' 
alternator & you were measuring current, not voltage? If so, the 
current 
measurement dropping to zero when you break the B-lead doesn't mean 
the 
alternator isn't 'putting out.' There won't be any current flowing 
because the circuit is no longer complete, but the alternator can 
still 
be producing voltage potential at the B-lead terminal. The only way 
to 
tell is to have a volt meter hooked directly to the B-lead terminal 
when 
you open the B-lead. Same idea as an electrical outlet in your 
house: 
120 VAC al the time but no current until you plug something in & 
turn it on.

The aeroelectric list hand-wringing about 'load dump' should only be 

relevant if you lose the connection to the *battery*. If the 
regulator 
fails & allows unregulated output from the alternator then the 
B-lead 
overvoltage disconnect relay described in the 'Connection' is what 
prevents the high voltage from damaging the a/c electronics. By the 
time 
you get to this point, 'load dump' is meaningless because the result 
of 
load dump (overvoltage) has already happened & preventing load dump 
is 
no longer an issue.

We'll talk when you get here on Friday.

Charlie

    

---------------------------------
Maybe I misled you. There are 2 wires hooked to the alternator. Only one
wire of the 3 on the plug, but the heavy wire going to the battery is
where I measured current. Are you saying I should measure the voltage on
the small connector wire?

I'm sure you can straighten me out this week end when we're are talking.

Thanks
Bernie

  

 Homepage:  http://www.flyrotary.com/
 Archive:   http://lancaironline.net/lists/flyrotary/List.html