From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>

Subject: Re: Cole-Hersee relay sticks

Date: November 28, 2013 at 11:53:49 AM MST

To: Giorgio Cagliero <gc5000@gmail.com>,aeroelectric-list@matronics.com

At 10:05 AM 11/28/2013, you wrote:
Hi,

I read on the Lancair mail list that a few builders had their starter contractor weld shut.
I am using a Cole Hersee 24047  http://www.colehersee.com/home/item/cat/183/24047/ (that's what Lancair supplies)

Would it be worth upgrading to a Lamar X61-0030  http://www.aircraftspruce.com/catalog/elpages/solenoidx610030.php  ?

Make current would go from 750 to 900A and Break current from 100 to 300A

Thanks for your insight!

Happy Thanksgiving,

Giorgio
---------------------------------------------
   With all due respect to a staid ol' supplier
   of electro-whizzies, this particular 'intermittent
   duty' contactor was never well suited to use as a
   starter contactor.

   RMB/Stancore/White-Rogers evolutions of the
   Model 70 contactor are also available in an
   intermittent duty version (higher coil current
   and somewhat enhanced closure forces).  Cessna
   use to use the intermittent duty versions too on
   the starter side . . . . wayyyyyy back when.

   The "problem" is centered around the design
   of contacts . . .

----------------------------------------------
The Cole-Hersee device is in the same family of contactors as
the 70 Series White-Rogers devices designed for continuous duty,
high carry-current and the switching of moderate loads.

http://tinyurl.com/koq788n

Here's an 'exploded view' for this class of contactor

http://tinyurl.com/mjndr93

Note the massive moving contact with LARGE area, hence LOW PRESSURE
footprint against the stationary contacts. This design will CARRY
lots of current but bounces like a golf ball. Especially vulnerable
to the ravages of high-inrush, somewhat inductive loads . . . like
starter motors.

http://tinyurl.com/mqpd92j

http://tinyurl.com/mtshbmj

Nice stationary contacts integrated with fat-wire studs . . .

http://tinyurl.com/k5674y9

"REAL" starter contactors have features unique to a device
specifically designed for intermittent duty switching of
large loads loads.

http://tinyurl.com/mmvkmeh

http://tinyurl.com/kcme565

Note the light weight moving contact with very small footprint
against the stationary contacts . . . very low mass . . . very
little bounce . . . much higher PRESSURE.

http://tinyurl.com/lgsmf77

Again, stationary contacts are integral with fat-wire studs.

http://tinyurl.com/kaqevb4

Note evidence of small area, high pressure mating of movable and stationary contacts . . .

http://tinyurl.com/krnf3n5

http://tinyurl.com/k582728

I am surprised to know that Lancair is offering that Cole-Hersee
product for this application. I did a weekend seminar at Lancair
some years back and we talked about characteristics of the two
kinds of contactors in some detail. The 'real' starter contactor
was a prominent character in the relays/switches/contactors segment
of the seminar.

Feel free to forward this email to the Lancair-List and even
directly to Lancair. The problems associated with mis-application
of this particular C-H contactor were predictable . . . but easy
to fix.

Cole-Hersee has a 'later' design that MIGHT be better
suited to task than the current selection

http://tinyurl.com/mxer975

But the architecture appears to be an evolution of the earlier
designs . . . without taking one apart, I cannot tell if this
device exploits the quantum leap in performance offered by low mass,
high pressure contacts.

I would suggest that the Lancair community consider replacing
the existing C-H device with something more like the SS598/1533
starter contactor with built in diode suppression.

http://tinyurl.com/pee3msa

Designed for this task, works good, lasts a long time . . .



 Bob . . .