|
|
|
|
|||||
|
||||||
(no email)
Date: Fri Jan 02 2004 - 01:14:17 EST
> Clamp on DC meters use a Hall effect sensor for the DC measurements.
> A hall effect device measures magnetic flux intensity instead of being a
simple
> transformer like the AC clamp on meter is.
>
SNIP
>
> Arild
>
Hmmm. I doubt if they use a Hall Effect sensor. Hall Effect sensors are
low on sensitivity, especially for measuring the DC magnetic field created
by smaller currents, and difficult to calibrate.
As I understand it, they apply an AC field on top of the DC one that has to
be measured. By using a ferrite material that has a saturation level they
can observe the degree of non symmetrical waveform on a pickup coil as the
AC drives it to saturation on each half cycle and so determine the DC
magnetic field from this since the half cycle adding to the DC will cause
saturation earlier in the cycle, and the opposing half cycle will need more
current to saturate. The difference is proportional to the DC magnetic
field from which you can determine the current flowing..
But it is a long time since I worked on that stuff and hall effect sensors
have perhaps improved since then.
Andina Foster,
_______________________________________________
http://lists.samurai.com/mailman/listinfo/trawler-world-list
To Unsubscribe send email to
Include the word "Unsubscribe" (and nothing else) in the subject or body of the message.
|