On Wed, 01 Oct 2003 23:36:31 GMT, "ATP"
wrote:

Ned Simmons wrote:
In article 9866af06.0310011228.3f2aa297
@posting.google.com, says...
No no no no. Think about it. The VOLTAGE is essentially constant at
all loads (120 V, 240 V or whatever the wall socket is giving). If
the power varies, the only way it can vary is by varying the current.

You're not only ignoring the issue of power factor
mentioned in several other posts, but also the fact that
the voltage output by the VFD varies with frequency. The
simple VFDs we're talking about here are often referred to
as volts/Hz drives beacause the voltage output when running
below base speed is proportional to frequency. For example,
the drive will deliver 24V @ 6Hz, when set up for a 240V
60Hz motor.

Ned Simmons

The Allen Bradley 1305 seems to have some sort of feedback loop running, it
makes adjustments based on what it thinks is the actual motor speed.

In the A-B's I'm using, you can select closed or open loop. For my
applications, I run open loop. I provide my own control loops
external to the drive. I don't know if the 1305 has the same feature
or not.

Pete Keillor