I wired the resistor.

At more or less the highest RPM, the mill can be stopped in 0.9
seconds. As I found out, I originally wired it for 3 seconds stopping
time. So this is an improvement (3.3 times less).

I am very happy.

I wish that the VFD reduced braking efforts, if it detects
overvoltage, instead of tripping on overvoltage. This is really not
too smart on the part of the VFD, unless I missed something. If it
could do that, then the mill would stop almost instantly at low RPM,
and longer at higher RPM.

i

On 2008-09-02, Mark Rand wrote:
On Tue, 02 Sep 2008 15:29:49 -0500, Ignoramus2176
wrote:


This is very encouraging. I think that what I will do after installing
the resistor, is try to take the stopping time as low as possible, at
highest RPM. Then I will back out just a bit. Almost instant stop, is a
very convenient thing.

i


Practically, the minimum braking time for the motor-VFD combination (with
suitable braking resistor) will be approximately twice the minimum starting
time that the VFD can drive the motor at. For the simple reason that it's
either going to be limited by motor torque or VFD capacity on the way down in
exactly the same way that it is on the way up.


regards
Mark Rand
RTFM

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