RE: (ET) Broken Breaker

["Elie, Larry \(L.D.\)" <lelie ford com>]

The best varnishes that people can afford go at 190 Deg. C.  That's for 
varnish that doubles the 
cost of the wire.  We use it for alternators because of package size and 
location.  GE did use good 
motors, but they wouldn't be above 190.  220 is the absolute max at very 
high price (at the moment).  
170 C is more common.  If you have a real voltage source (and battery 
vehicles are NOT), you 
can voltage limit on the resistance of the coil, which can be determined 
and set in the design 
stage to happen at a particular temperature.  The result is when it gets 
hot, the current 
drops at the same rate as the temperature increases.  Fairly failsafe.

Larry Elie


-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Geoff Rich
Sent: Friday, July 23, 2004 12:03 PM
To: et
Subject: RE: (ET) Broken Breaker


It looks like TI has completely re-done the Klixon webpages.  From some 
stuff I figured out before:

P=precision  (tighter specs on temperature derating of ultimate trip point)
or
C=normal (standard temperature derating of ultimate trip point)
or
S=square/rectangular case with normal derating

D=sealed construction (has the metal backplate)
or
(no letter)=open (no backplate)

L=large frame size (as used on traction motor in E12, E15/16, E20)
or
(no letter)=small frame size (used on mower motors, & for CB2 on upper 
control panel)

A=automatic reset
or
M=manual reset (the big red button).

Amperage follows the prefix letters.

It looks like TI no longer lists the CLDA or CLA type breakers in the 
larger amperages;  I guess we will now have to sub with the SLDA or PLDA 
instead.  SLDA should fit, since the bolt holes are still ~2.4" OC.  
PLDA's have same exact case as the CLA's/CLDA's did, so they are drop-in 
replacements, but they might be more expensive due to their "precision" 
specs.

I wouldn't recommend the "open construction" type (SLA or PLA), as water & 
dirt could get inside the breaker.

Looking at the derating curve, I think I see why GE mounted these right on 
the motors.  At higher temperatures, they trip at less than the rated 
amperage.  If a motor's already hot, you probably don't want to make 
things worse by allowing the maximum permissible current to flow in the 
armature.  As anyone who has ever done any wire sizing knows, it's all 
about keeping the temperature of the insulation material well below the 
point where it starts turning into a carbon resistor. (For varnish, I 
think it's about 150-200°C?)

-Geoff


-----Original Message-----
From: SteveS [mailto:ssawtelle fcc net]
Sent: Friday, July 23, 2004 9:57 AM
To: et
Subject: Re: (ET) Broken Breaker


Thanks Tom and all,

The one I took off the E12S is a CDLA-80. which must be an 80 amp 
device, makes sense since it is an E15 motor. I'm not sure what the diff 
is between PDLA and CDLA. The 'A' means automatic reset. I think the 'L' 
is the basic size/style.  The TI web site isn't real clear on the part 
number meanings.

You must be right about wanting some extra senstivity to the motor heat, 
because it takes a bit of extra wiring to put it there.

- SteveS




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