[RE-wrenches] Power-Save and Power Works

[Darryl Thayer]

Hi peter
Very interesting question and perhaps the fellow from excel tech could help.  First the current limits from an inverter is for total current, both reactive and in phase.  But the starting and running currents for motors are from both reactive and in phase current.  Is the reactive current large on motor starting?  I expect the reactive current is small on start surge.  On running however the reactive current depends upon load.  

Some one know?
Darryl


--- On Mon, 8/25/08, Peter Parrish <peter.parrish at calsolareng.com> wrote:

> From: Peter Parrish <peter.parrish at calsolareng.com>
> Subject: Re: [RE-wrenches] Power-Save and Power Works
> To: jryago at netscape.com, "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
> Date: Monday, August 25, 2008, 10:14 AM
> This is a pretty important measurement. I was hoping that
> the Power-Save was
> eliminating the out-of-phase current, leaving only the
> in-phase component.
> But if it throttling down the in-phase current as well,
> that's another
> story. It would be nice to know the Power Factor in both
> cases, which would
> answer the question.
> 
>  
> 
> Let's assume for a moment that the Power-Phase does
> eliminate the
> out-of-phase current, but not the in-phase current.The
> immediate question
> that comes to my mind is "Are the current specs for an
> inverter (continuous
> and surge) based on in-phase current or the total current,
> part of which is
> in phase and part out of phase?" I suspect it is the
> latter (total current).
> In which case the Power Phase (or its equivalent) would be
> useful in
> presenting lower (motor based) surge currents to an
> inverter.
> 
>  
> 
> Another question that I have thought about every since I
> bought my first
> Kill-a-Watt, "Is there a similar version for 240V
> loads? I suspect that one
> could kludge two 120V Kill-a-Watts together in a j-box and
> make it work some
> how, but a real 240V version at a reasonable price would be
> great news.
> 
>  
> 
> - Peter
> 
> Peter T. Parrish, peter.parrish at calsolareng.com 
> 
>   _____  
> 
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
> Behalf Of Jeff Yago
> Sent: Sunday, August 24, 2008 8:56 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Power-Save and Power Works
> 
>  
> 
> 
> On start up, the A/C unit went up to 91 amps and leveled
> out at 13 without
> the Power-Save 1200 on. When the Power Save unit was
> engaged it was a draw
> of 35 amps and leveled out at 8.75. That pretty much blew
> everyone away!
> After that, I tested everything with a motor load in my
> house. I was
> astonished at the significant reduction in amperage.
>  - - - - - - - - - - - - - - - - - - - - - - - - - 
> 
>  
> 
> You note they are not measuring the output of the device
> being connected.
> For example, they are reducing the current draw of the
> motor in the AC unit
> by slowing it down a little, which will reduce the cooling
> output by same
> percentage.  Like a variable-speed-motor drive, yes you can
> reduce the motor
> current draw, but you are also slowing down the fan, pump,
> or compressor it
> is driving.  Only time this may be an advantage is if you
> want to reduce the
> output of the device being driven as part of redicing its
> current draw.
> 
>  
> 
> Jeff Yago
> 
> 
>  
> 
>   _____  
> 
> Netscape.  Just the Net You Need.
> 
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