On 2007-10-29, Ned Simmons wrote:
On Sun, 28 Oct 2007 20:13:28 -0500, Ignoramus32225
wrote:


I looked into the manual, available at

http://igor.chudov.com/manuals/

and found reference to parameter 1300, V/F curve. It talks about
different selections, such as linear V/F, parabolic etc. It says that
linear V/F is better for constant torque and "positive displacement
pumps".


Make sure parameters 0304 (Rated motor voltage), 0310 (Rated motor
frequency), and 0311 (Rated motor speed) match the motor nameplate. If
they don't, the slope of the V/f curve will be wrong, i.e., the motor
will see an undervoltage or overvoltage condition which will get worse
as the speed increases.


Ned, yes, I did set it correctly. I remember. It also did not help
much.

I also saw this:

http://www.sbt.siemens.com/HVP/Compo...csOverview.pps

See slide 16 out of 17.

Apparently, this SED2 drive has a very small capacitor compared to
other drives. Only 20 uF compared to 1,000 uF for other drives, with
the example of a 15 HP drive. (unspecified voltage)

That might, in my mind, account for voltage sagging when run from 1
phase, and low voltage delivered to motor.

So, a possibility to ponder would be to add some capacitance between
DC+ and DC-. The terminals are available for connecting, but I am not
sure of ramifications of, for example, inrush current greatly
increased.

Any thoughts on this?

i