On 2007-10-23, Jon Elson wrote:


Ignoramus705 wrote:
The 10 HP compressor is now in my yard. Looking good, but needs a
little cleaning.

I will hopefully receive the VFD on Friday or so. It is a Siemens SED2
18.5 kW rated drive. Assuming it works, I have to set its parameters
and here's where I need a little bit of wisdom.

Specifically, my question is how do I set the acceleration ramp-up so
that it works nicely with the unloaders. My own thinking is that I
should accelerate slowly almost up to the speed when unloaders kick
in, and then accelerate as fast as I can once unloaders do kick in and
the pump starts pumping. Any idea what is the speed when unloaders
kick in?
Depending on the unloader system, it may be entirely pneumatic time delay,
or hydraulic. Especially if hydraulic, it will not be at a specific
time. The first start of the day will take longer. Just set the ramp
up so the lights don't dim too much when spinning up. Roughly one
second might be a good starting guess. I can't see any reason to not be
fully at speed (60 Hz) before the compressor gets loaded.


1 second is definitely what I will start with. My mill also has a 1
second delay, it feels very nice.

i