Following opinions are mine alone, and were heavily influenced by my lunch-time 

Looked at one about 10 years past and decided the design was, in my opinion, 
'marginal' per scoped safety standards; but have not looked at any recent 
product versions. Not accurate for high crest-factor stuff, and some inductive 
loads gave it temporary insanity. Readings were usable and reasonable over a  
limited temperature range (probably because of the current shunt's tempco) and 
for specific load types.

Many comments floating around the internet on this product, so there is 
probably a decent technical write-up available.


From: alfred1520list [] 
Sent: Monday, February 12, 2018 2:34 PM
Subject: Re: [PSES] Current measurement

While on the subject, any one familiar with the Kill A Watt meter? This listing 
sells for US$26 and free shipping: 

I swapped out the 2 mOhm current sensing resistor with a 0.2 ohm resistor (and 
of course greatly limiting the current capability) so I can measure standby 
power down to 10 mW. I did test with a 7 W incandescent light bulb and it 
reported reasonable readings. I tested are few phone chargers with nothing 
plugged and they idle at less than 50 mW. (But I don't know if I trust the 
figure down to decimal point:) 

It could be a really inexpensive way to get a reasonable (but not certification 
grade) power measurements. 

Best Regards, 

On February 12, 2018 1:36:10 PM PST, Brian O'Connell <> 
Will admit to having done this stuff with using microcontrollers and discrete 
sequential data channels and of sufficient sampling speed, but am subject to 
frequent bouts of idiocy. And this was for process control, and thus not a Type 
Test. Also, note that there is a difference in technique and equipment between 
power loggers and an analytical instrument.

Best done with an instrument intended for this measurement; that is 'power 
analyzers'. Typically found on shelves at Keysite, Tektronix (nee Voltech), 
Ametek, Chroma,  etc. And many Tek and keysite DSOs have a 'plug-in' for doing 
power measurements. All of this instrument-grade stuff can easily handle 
external sensors.


-----Original Message-----
From: Amund Westin [] 
Sent: Monday, February 12, 2018 1:05 PM
Subject: [PSES] Current measurement

If you want to calculate t!
consumed power (W) in a 1-phase AC circuit, you
can use a current clamp-on device to measure the current in one lead/wire
and multiply with the applied voltage.
But with such a current clamp on device, to we measure the apparent power
(VA) or the real power (W)?

Best regards

Sent from my Android phone with K-9 Mail. Please excuse my brevity.

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