Power factor issues [RE-wrenches]

[Bill Brooks]

Allan,

All the PV books and training I have seen use Watts to calculate loads on
inverters. I think this is the wrong way to do it if you are considering
power handling capability.

An inverter is a Volt-Amp device, not a Watt device. Measuring the effect of
a CFL should be done by using a good true RMS current meter (like a fluke
87) and multiplying the current by the voltage (volt-amps). Devide the Watt
draw by the Volt-amp draw and that will be the power factor for the
non-sinusoidal load. This is not a displacement power factor issue like with
a motor load--the load has a very weird current waveform. Computers also
have terrible non-sinusoidal waveforms. A 300-Watt computer power supply can
draw up to 500 Volt-amps.

Don't know if this helps.

Bill.

-----Original Message-----
From: Allan Sindelar [mailto:allan at positiveenergysolar.com]
Sent: Tuesday, May 13, 2003 7:12 PM
To: New wrenches posting
Subject: Power factor issues [RE-wrenches]


This is a repost of a request I made on 4/2; nobody responded to any of the
questions. I'm trying one last time. Maybe nobody cares, in which I won't
either.
Allan

----- Original Message -----
> Fellow Wrenches:
> 1. What do you use to measure power factor on AC loads? It looks like the
> Brand 20-1850 is a good bet, but is there anything that's good, easy to
use,
> and cheaper?
>
> 2. Do you bring up power factor when sizing power systems or when
discussing
> CF bulb selection? Does anyone carry and sell high power factor CF bulbs
for
> this reason?
>
> 3. Has anyone determined by actual measurement that it takes less DC power
to
> run a high power factor CF bulb than a low power factor CF bulb? How much
> less?
>
> 4. In other words, I have read Sylvania's piece on the relationship
between
> beer and foam. How much attention should we pay to this issue?
>
> Thank you.

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