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KAW Question

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Posted by Daniel Armstrong on April 28, 2006, 9:11 pm

I have noticed that the Kill-A-Watt and the Seasonic PowerAngel are
identical and was wondering if anyone has more information.

Exhibit A the KAW:
Exhibit B PowerAngel: http://www.seasonicusa.com/products.php?lineId=8  

Posted by Neon John on April 29, 2006, 1:58 am

On Fri, 28 Apr 2006 21:11:24 GMT, "Daniel Armstrong"

Just guessing.  The KAW is made in Taiwan.  The other one is probably
the chinese knockoff.

I've compared both my KAWs to a laboratory standard and both are quite
accurate.  No knowledge of the knockoff.

If you need more functionality including battery backup and higher
power handling capability, then I recommend the Watts Up line.

John De Armond
See my website for my current email address
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain

Posted by meow2222 on May 1, 2006, 12:49 am

Neon John wrote:

I've heard others say it depends on the waveform, with it being way off
with some loads. Not tested them myself though.


Posted by ITSME.ULTIMATE on May 10, 2006, 11:25 pm


Hello John,
    I own a Valhalla power analyzer, Kill-A-Watt and (had) a Watts Up
Pro.  The Valhalla power analyzer cost $,100 ish new and this is what I
used as a reference.  The Kill-A-Watt consistently read close to the
reference.  It is an impressive meter for $5 shipped.  

The "Watts Up" line is available in three models and the higher two
models have computer interfacing capability but I believe the sensing
assembly are the same across all three modoels.  The Watts Up is within
the specified accuracy using a truly resistive load, such as a
lightbulb, but two different Watts Up units from different lots I've
owned did not handle inductive loads well at all. They both showed a
level of error well in excess of the specifications, in fact to quite an
unacceptable level in my opinion. The first unit I owned read high and
was outside the guaranteed accuracy, so I sent in for a replacement.  
The replacement read 20% low.  

Just where might you encounter a non-unity inductive loads?  Basically,
anything with an induction motor, such as: refrigerators, a window air
conditioners, fans, among other things.  The merit of an AC power meter
over a simple ammeter is the ability to measure the real power of non-
unity and non-sinusoidal loads, which my samples of Watts Up didn't do
Both units have been returned to the manufacturer and they have been
able to reproduce the problem, but they're not able to provide a they
can guarantee to meet the instrument's original specifications,
therefore, I don't believe this is an isolated incident affecting only
my two units.

If you happen to own a Watts Up meter and you have a reference meter,
you should compare the readings on them using an induction motor as the
load.  If you don't have a reference meter, connect a bank of motor
start capacitors.  The volt ampere value (voltage x ampere) should be
quite substantial while the wattage reading should be negligle as the
voltage and current phase are almost 90 degrees out of phase. If you get
a substantial wattage reading, your Watts Up too suffer from phase


Posted by Neon John on May 11, 2006, 5:53 am

On Wed, 10 May 2006 16:25:36 -0700, ITSME.ULTIMATE

Yes, I have a watthour meter calibration bench that I maintain
traceable.  My old Watts Up did fine down to 0.5pf. I haven't checked
any lower.

The two I just bought (pro and pro es) have a different "feel" which
means the firmware is significantly different.

I haven't had time to check them but I will before using them for
customer (paying) work.  I did notice that the Pro behaved quite funny
when connected to my washing machine.  The skeletal motor in the thing
is a low PF load and the PF varies widely over each agitator cycle.
The PF indication was all over the place. I need to hook the Pro ES up
and do a datalog to see what is happening.

I'll followup when I get more data.


John De Armond
See my website for my current email address
Cleveland, Occupied TN
Don't let your schooling interfere with your education-Mark Twain

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