Hi Ken:
> My understanding is that this is a dc measurement, hence the discussion of
> waveform potential and phase doesn't apply. If it were an ac measurement,
> this would be a very important consideration, but it doesn't bear on the
> current probe shunt selection.
If the measurement is inrush current, then it is a
line-frequency measurement over several cycles.
It is an AC measurement of an exponentially
decaying series of near sine-squared pulses of
which you want to know the peak value of the
first pulse.
You don't need a big window for the current probe
because you are measuring a #18 or #16 AWG wire.
But, you need a probe that will handle the current,
i.e., won't saturate the core. Usually, this is
a larger current probe with an associated larger
window.
On 120 and 230-volt power systems, the inrush
currents will range from 40 amps to as much as
120 amps (for the first 1/2 cycle, with switch-on
optimized for maximum inrush current). On a test
bench using a really low source-impedance power
source, inrush current could be more than 120
amps.
Retracting my previous statement, certainly a
current shunt can be used in place of the current
probe.
On the other hand, if the EUT is a dc-operated
device, then the inrush current is still an ac
waveform, starting with some sort of step function
followed by an exponential decay to the steady-
state current.
Best regards,
Rich
This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.
Visit our web site at: http://www.ieee-pses.org/
To cancel your subscription, send mail to:
[email protected]
with the single line:
unsubscribe emc-pstc
For help, send mail to the list administrators:
Ron Pickard: [email protected]
Dave Heald: [email protected]
For policy questions, send mail to:
Richard Nute: [email protected]
Jim Bacher: [email protected]
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
