Re: [Emc-users] [OT] power factor and VFDs (was "Single Phase Lathe spindle motor question")

[Jon E. <el...@pi...>]

Kent A. Reed wrote:
> Still, Roger's comment intrigues me. A home-based shop could cause 
> mystifying problems in the household if the power factor gets out of 
> hand. Do VFDs really make this a non-issue?
>   
Unless you have REALLY marginal power, such as a 60 A 240 V feed, and 
central air conditioning,
electric clothes dryer, etc. I just wouldn't worry about power factor.

Yes, modern VFDs are designed to keep the power factor relatively high, 
maybe 80% or so worst-case.
They do give a non-linear distortion by drawing their current at the 
voltage peaks, but the phase angle
is kept small.

Probably the BEST feature in this regard is slow-start.  You can set the 
acceleration ramp for a fraction
of a second, and there is no dimming of lights when large motors are 
started.  If I had my 7.5 HP lathe
on an RPC, I know the lights would dim appreciably when I started it.


Jon