The manual differs slightly from the controller. The min is 2-20,
the max is the min that was set to a max of 60. So you can put the
min and max at 2a, but that would basically take away the field
weakening.
What is the field current limited to in the Alltrax sep-ex version
for the ET?
Contactor for main power: The 1244 and 1243 both kind of require
it. You would have to use an OEM version of the programmer to
remove this restriction. The curtis series controllers...Well,
that's another story. Some require it, others don't. Should
it be there? It probably should be. Like the seat switch. :) It
should be working too.
Single part verses multiple parts: I would like to go with: The one
that lets me do the most amount of work. The toaster and card 3
& 4 irk me. Wastes my precious power. :) I like the idea of an
electronic controller because it should be easier to
maintain. Less parts to trouble shoot...but, as you said, at a
higher replacement cost.
On 2/16/2011 11:25 PM, Jim Coate wrote:
According
to the Curtis 1244 manual (pp 36-37) at
http://www.curtisinstruments.com/index.cfm?fuseaction=cProducts.DownloadPDF&file=ACFWC9e9x1.pdf
the minimum field can range from 2 to 20 amps,
the maximum field can range from 7.5 to 60 amps.
This is off by an order of magnitude for what the ET motor needs.
As others have said, its field is around 2 amps *maximum*.
So I'm not sure how this controller could ever provide field
weakening with an Elec-Trak? And if it can't, may as well use a
less expensive series type controller for the armature only (if
avoiding the Alltrax sep-ex version for the ET).
While simple is generally good, and altering gear ratios is an
interesting approach to a higher top speed, eliminating the main
contactor makes me nervous. Curtis and all the other
manufacturer's suggested wiring diagrams always include a main
contactor and any needed pre-charge circuitry. The contactor is
there as a safety to open up in case the electronics fail, and
MOSFETS have a habit of failing shorted, as in full power on!
As for the "best" control system... Those who can correctly use
the term "l/h transition" in a sentence are likely able to install
and repair a system with discrete relays, while others like a
single black box which while more expensive to replace greatly
reduces the number of parts to deal with. Some care about field
weakening, some don't.
So it all depends on the person.
Brian E. Haines wrote:
All of this does bring up a couple of more
questions...
Would you recall what the field min/max you used with the
curtis controller? The 1244 allows from 0 to 20a min field, and
0 to .,...like 130a for the max field. Do you recall the field
map?
Thanks
B
On 2/10/2011 6:06 PM, Clean Power Supply wrote:
I agree that the Curtis controllers
used in this manner are quite practical. And now I'll share my
secret: I have top speed WITHOUT weakening the field. I use a
larger motor pulley with a smaller trans. pulley, sized
appropriately to achieve top speed with full field voltage.
Since speed control with an electronic controller is almost
infinite,losing the lower gearing is of no great consequence.
Additionally,I don't use *any* contactors,only a master
disconnect switch. The switch on the pot is used to turn the
KSI (Key Switch Input) on the controller on and off. A toggle
switch with center off is used to reverse the field polarity
thereby achieving motor reversal.The center off turns off the
KSI,requiring the foot pedal to be brought back to neutral to
restart.This prevents slamming from F to R while the motor is
running and also gives a bit more time for the field to
collapse before polarity reverses.I do use a varistor to help
with that,though.
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