On 11/12/2010 12:56 AM, Dave H. wrote:
Well, despite the lack of schematic / service manual / help from ABB, I now
have a nice new blue-lit LCD (tarty eh?) and access to the programming


[1] - I guess I need something that'll dissipate about twice the
motor power for a fairly rapid stop, so 4KW upwards - any reason I
shouldn't use halogen heater elements and warm the shed up?

Check the users manual, there is usually a minimum braking resistor
value specified somewhere. I think the minimum is to limit the current
through the switching transistors.

BobH

Well, despite the lack of schematic / service manual / help from ABB, I now
have a nice new blue-lit LCD (tarty eh?) and access to the programming

After unsoldering the jack to the programmer from the top board, buzzing
tracks out and remaking all the solder joints nearby, I looked closely at
the jack itself and discovered one of the spring contact pins had bent flat
(presumably when the programmer panel tried to occupy the same space during
the "drop test") and lodged in a notch in the moulding (notch for what?
Pass!), a tweak with a spring hook and I had power to the programmer, an
added 100-Ohm SMD resistor and a couple of jumpers to the DC + and 0v lines
on the replacement LCD module (£2 inc. shipping, Chinese MC1601a equivalent)
and it lit up a pretty pale blue colour. Looks much more modern than the
original slime green LCD I may have to paint it up, now...

I am chuffed, but it rubs in "Check the physical layer first!"

Now to find out where SWMBO has tidied (or hoovered) all the tiny screws to
hold the programmer together, and work out how to hide it in the lathe base
along with a braking resistor[1]... After I celebrate with a nice warm
English beer.

Thanks to all for their input,

Dave H.
--
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader

[1] - I guess I need something that'll dissipate about twice the motor power
for a fairly rapid stop, so 4KW upwards - any reason I shouldn't use halogen
heater elements and warm the shed up?

"BobH" wrote...

Check the users manual, there is usually a minimum braking resistor value
specified somewhere. I think the minimum is to limit the current through
the switching transistors.

BobH


I'll certainly look into that some more - after a thorough read of the user
manual I was none the wiser, but judging by the ABB braking resistor
quick-start guide I found on t'web, I will need a 32 Ohm, 2KW continuous /
12KW peak rated resistor if I want "heavy-duty" braking on a 3HP motor -
this suggests to me that it'll be expensive as an ABB item, so I may build
it myself with a rackful of 1KW halogen elements - they're about 60 Ohms
each, so a bunch of pairs in series/parallel (3x3?) should handle the peak
power dissipation and would have the advantage that the applied voltage will
be divided across 'em and stay below their 240V rating - should warm the
shed up nicely, too

I did some back-of-a-spreadsheet calculations, it looks like 12KW peak would
give me a brake-to-stop of under 1/2 second at 1500 RPM - that would be
pretty hard on the lathe, though! More appropriate would be a dead stop
(1/10 sec, under a quarter-turn) at 120 RPM at the end of a threading pass,
much less stressful but still pretty quick considering a big chuck and
workpiece?

I am, of course, aware this may be wrong, so any advice will be very
welcome!

Dave H.
--
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader

On 2010-11-11, BobH wrote:
On 11/12/2010 12:56 AM, Dave H. wrote:
Well, despite the lack of schematic / service manual / help from ABB, I now
have a nice new blue-lit LCD (tarty eh?) and access to the programming


[1] - I guess I need something that'll dissipate about twice the
motor power for a fairly rapid stop, so 4KW upwards - any reason I
shouldn't use halogen heater elements and warm the shed up?

Check the users manual, there is usually a minimum braking resistor
value specified somewhere. I think the minimum is to limit the current
through the switching transistors.

And calculate based on the cold resistance -- it will take a
while for the halogen heater elements to get hot enough to reach
operating temperature and resistance.

Good Luck,
DoN.

--
Remove oil spill source from e-mail
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Congrats.. persistence and attention to detail have their rewards.

Some folks use a combination of heating elements for power loads. The LERs
(light emitting resistors) you comment on will likely work just as well as
the dark ones.

Kitchen cooking oven elements have been reported to be good loads, so there
are many varieties of cooking-type elements that may be suitable.
It may sound a bit over the top, but some power load resistors are submerged
in mineral oil.

--
WB
..........


"Dave H." wrote in message
...
Well, despite the lack of schematic / service manual / help from ABB, I
now have a nice new blue-lit LCD (tarty eh?) and access to the programming


After unsoldering the jack to the programmer from the top board, buzzing
tracks out and remaking all the solder joints nearby, I looked closely at
the jack itself and discovered one of the spring contact pins had bent
flat (presumably when the programmer panel tried to occupy the same space
during the "drop test") and lodged in a notch in the moulding (notch for
what? Pass!), a tweak with a spring hook and I had power to the
programmer, an added 100-Ohm SMD resistor and a couple of jumpers to the
DC + and 0v lines on the replacement LCD module (£2 inc. shipping, Chinese
MC1601a equivalent) and it lit up a pretty pale blue colour. Looks much
more modern than the original slime green LCD I may have to paint it
up, now...

I am chuffed, but it rubs in "Check the physical layer first!"

Now to find out where SWMBO has tidied (or hoovered) all the tiny screws
to hold the programmer together, and work out how to hide it in the lathe
base along with a braking resistor[1]... After I celebrate with a nice
warm English beer.

Thanks to all for their input,

Dave H.
--
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader

[1] - I guess I need something that'll dissipate about twice the motor
power for a fairly rapid stop, so 4KW upwards - any reason I shouldn't use
halogen heater elements and warm the shed up?

Cautious on the light bulb replacements - the cold current is about 10x
that of the hot current. They get so hot as compared to resistors -
the thermo-resistance curve isn't linear.

Martin

On 11/11/2010 8:45 PM, Dave H. wrote:
"BobH" wrote...

Check the users manual, there is usually a minimum braking resistor value
specified somewhere. I think the minimum is to limit the current through
the switching transistors.

BobH


I'll certainly look into that some more - after a thorough read of the user
manual I was none the wiser, but judging by the ABB braking resistor
quick-start guide I found on t'web, I will need a 32 Ohm, 2KW continuous /
12KW peak rated resistor if I want "heavy-duty" braking on a 3HP motor -
this suggests to me that it'll be expensive as an ABB item, so I may build
it myself with a rackful of 1KW halogen elements - they're about 60 Ohms
each, so a bunch of pairs in series/parallel (3x3?) should handle the peak
power dissipation and would have the advantage that the applied voltage will
be divided across 'em and stay below their 240V rating - should warm the
shed up nicely, too

I did some back-of-a-spreadsheet calculations, it looks like 12KW peak would
give me a brake-to-stop of under 1/2 second at 1500 RPM - that would be
pretty hard on the lathe, though! More appropriate would be a dead stop
(1/10 sec, under a quarter-turn) at 120 RPM at the end of a threading pass,
much less stressful but still pretty quick considering a big chuck and
workpiece?

I am, of course, aware this may be wrong, so any advice will be very
welcome!

Dave H.