RE: (ET) fuses and breakers

["Hazen, Dwight L" <hazen indiana edu>]

Larry,

I have installed an "E" meter that has a 500 amp shunt on my E14 and I have
seen currents well over 200 amps. The E14 now has  an E20 motor as the
original PM drive motor went up in smoke! I have never had any of the
thermal breakers kick out! This includes the mower decks on the E14 and
E12M. I am now wondering if all the thermal devices are welded/rusted 
shut? 

What would be a good way to test the circuit breakers?

I am rebuilding an E20 and was trying to figure out how to test the thermal
cut-out that bolts to the motor. I put heat sink compound the back of it so
it could react faster to a hot motor. It seems to have a set screw in the
center of it. I wondering if turning the set screw will change the temp 
that
the cut-out will trigger?


  Dwight 

Dwight L. Hazen, Indiana University, UITS 
Bloomington, In. 47408-7378 812-855-5367 hazen indiana edu
http://php.ucs.indiana.edu/~hazen/ Ham Radio wb9tlh arrl net


> -----Original Message-----
> From: Larry Elie [SMTP:lelie ford com]
> Sent: Monday, November 01, 1999 9:58 AM
> To:   elec-trak cosmos5 phy tufts edu; 'David Howard'
> Subject:      RE: (ET) fuses and breakers
> 
> Thanks for setting us straight Dave.  I was the confused individual who
> proceeded 
> to spawn confusion.  I have done fuse testing (20+ years ago) but never
> done a 
> breaker test in my life.  I should have guessed an I square R for the
> power in the 
> 'passive' device.  Duh.
> 
> Now the problem.  Even today, someone posted shunt values for the meter 
> of
> an 
> E-20.  Note the E-20 has a 50 Amp breaker on the armature.  The values 
> for
> the 
> green range extended to 75 Amps.  This compares rather well to the values
> I 
> saw with a Hall-Effect Clip-on (to my Fluke digital) on my E12.  The
> yellow range 
> extended to 121 Amps, and the red ended at 156 amps.  I was able (by
> pushing 
> on a dirt pile with the blade to nearly pin the meter (~200 Amps at Hall)
> for tens of seconds.  
> I have pushed gravel for over an hour between the upper green and yellow.
> These are 
> on the order of 100 Amps, or more than twice the value of the 40 Amp
> breaker in my 
> E12.  I have never tripped it.  Someone else posted a clip-on value of 
> 600
> Amps, which 
> I think should take out the fusible link, but it didn't.  Even for a
> 'slow-blow' breaker, I have 
> a hard time understanding how this could work.  Secondly, even at 100
> Amps, we 
> are only talking about something like 5 HP; and GE's 'rating' would be as
> bad as 
> the Sears ratings on their saws.  At 40 amps, my GE would be about 2 HP,
> making 
> Sears look honest.  Sure, part of the 'rating' might include the deck
> motors, but they 
> are only about 1 HP (by my calculations... now suspect) each.  I do 
> design
> of high-field 
> devices (clutches) for part of my job, and I am having some real problems
> here.  
> 
> The bottom line is how can an E-20 win in a tractor pull?  And how does a
> 40 Amp breaker 
> handle 100 Amps for over an hour?
> 
> Larry Elie
> 
> 
>