In article
,
notme wrote:

Fluke clamp current meters have 2 features that seem similar: peak and
in-rush. The older models have Max (some: Peak). The recent advent in Fluke
clamps is "In-rush".

How do these differ? Isn't in-rush current the short, max current at
motor-turn on? Shouldn't meters with a Max feature capture this accurately?

Compare, for example, my old Fluke 36 (Max):

http://assets.fluke.com/manuals/36______iseng0000.pdf

and the 334 (In-Rush):

http://us.fluke.com/VirtualDemos/330shock.asp

(click "Explore" then "Selection Guide").

How do Max & In-rush differ? Only in the marketing department?
Or is there a real-world difference?

Thanks,
Dave

The essence of one of these meters is a current transformer using a core
that can be opened and then closed. In the closed condition, the
magnetic reluctance of the core is made as small as possible. The
secondary coil is connected to a small resistance. The idea is to have
the current flow waveform in the secondary duplicate the current flow in
the often single turn primary. The voltage on the resistor than
duplicates the current waveform.

How this secondary waveform is used and processed will determine the
features of the meter. Fluke is one of the big names in hand held
oscilloscopes. It is possible to digitize the start of this waveform.
Then various algorithms can be used to characterize the waveform
including the start of it.

Bill

--
As the years go by, dying just before having to fill out a tax return has merit.