On Sat, 14 Jun 2008 19:13:11 -0500, "RogerN"
wrote:

This is a machine our companies German owners crammed down our throat that
was supposed to be running by the end of March. The first thing I thought
of was changing the gear ratio and speeding up the motor but since it's not
complete and not turned over to us, we have to get the stubborn Germans to
agree to everything. I thought if it would do any good I could sneak and
enable the sensorless vector control without them knowing, if it would do
any good. I guess I thought if it could give 100% torque at zero rpm, it
should give 100% torque at 1, 2, or 3rpm, I guess not.

This is for a weighing system that doses out chemical for rubber mixing and
a dose could be from 0.07lbs to 20lbs all with an accuracy of 1% or 3g,
whichever is greater. It has a coarse dosing and fine dosing, it's
difficult to run slow enough to hit the target on smaller weights and be
able to run fast enough to dose 20lbs in ~ 13seconds with 1% accuracy, all
with a drive programmed for 60hz. But what do Americans know, they have
"superior German Engineering". Also, we wanted Allen Bradley Controls but
Siemens was crammed down our throat. Now we're busting our butts trying to
help them get it to run...

They just discovered the low speed torque boost settings, and are going to
show me how to enable it. They don't know that I already did it for some of
the stations (35 in all).

Thanks

Roger N


at those speeds...even stepper motors would be better....3 hz??????

gunner


"Gunner Asch" wrote in message
.. .
On Sat, 14 Jun 2008 05:45:19 -0500, "RogerN"
wrote:

We are running equipment at work that have Siemens MicroMaster drives. In
some cases we need speed settings below 5% (below 3hz) and are having
difficulty getting good torque and speed control.

no ****.

change the pulleys to reflect a better torque range at that low speed
and run the drive at a higher speed.


I noticed these drives
have a setting to enable sensorless vector control. I was wondering if
anyone here has experience with using sensorless vector control on drives
and if you think it would give us good speed control at low speeds?

Thanks!

Roger N

not that low.


You are going to have to find a happy medium between your maximum rpm
and your minimum rpm and change pulleys to reflect that ratio

Or put in a 2 speed gear box


Gunner



at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
mariposa rand mair theal


at yoyodyne they were all veterans of the psychic wars
exiled from the eighth dimension where the winds of limbo roar"
* * * * * * *mariposa rand mair theal