Output Voltage vs. Firing Rate (fwd)

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Output Voltage vs. Firing Rate (fwd)
From: Tesla List <tesla-at-stic-dot-net>
Date: Sun, 16 Aug 1998 11:03:43 -0500
Approved: tesla-at-stic-dot-net

----------
From:  Harri Suomalainen [SMTP:haba-at-cc.hut.fi]
Sent:  Saturday, August 15, 1998 7:29 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: Output Voltage vs. Firing Rate (fwd)

>I hadn't realized about the rms problem.  This wattmeter says it's 
>accurate to 1/4 of 1 % up to 125 Hz.  I wonder how severe the errors
>might be?  Has anyone compared such wattmeters with true (electronic)
>reading wattmeters in TC circuits to get a ball park figure of possible
>errors?

That depends a lot on meter. I just ran into a very affordable kWh/wattage
meter. Some investigation proved it would be practically useless with
any waveform disortion. Yet, it was specified to have 3% accuracy!

With high-frequency signals meter bandwidth may also be limitation
with many meters, including some electronic meters which might
be slow sample-multiply-indicate systems.

>Also any clue as to how inaccurate the rms technique might be
>(ignoring power factor issues for now)?

One easy way to do a power meter is to measure current and voltage
(by transformers, resistive dividers or whatever) and then multiply
those. Multipliers like MC1495 should give you pretty nice bandwidth
(about 1MHz or so). Making such a meter would not be too difficult.

Such a meter would be able to show true VA or wattage depending
on the output section. I'd go for that method if power was interesting.
Lots of examples are available in the literature.

--
Harri Suomalainen     mailto:haba-at-cc.hut.fi

We have phone numbers, why'd we need IP-numbers? - a person in a bus