Iflexi Current Probe - Fluke 1775 User Manual

iFlexi Current Probe

The iFlexi Current Probe works on the Rogowski coil (R-coil) principle that is a toroid of wire
used to measure an alternating current through a wire encircled by the toroid. See
The R-coil has advantages over other types of current transformers:
It is not a closed loop. The second terminal is passed back through the center of the toroid

core (commonly a plastic or rubber tube) and connected along the first terminal. This allows
the coil to be open-ended, flexible, and able to be wrapped around a live conductor without
disturbing it.
It has an air core rather than an iron core. It has a low inductance and can respond to fast-

changing currents.
Because it has no iron core to saturate, it is highly linear even when subjected to large

currents, such as those used in electric power transmission or pulsed-power applications.
A correctly formed R-coil, with equally spaced windings, is largely immune to electromagnetic
interference.
1.800.561.8187 1.800.561.8187
Figure 5. R-Coil Operation Principle
i(t)
A
10 k
V
in
v(t)
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3 Phase Power Quality Analyzer
R1
330 k
R3 V
out
C1
10 nF
UI:A
2
1
3
LF347
GND
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Before You Start
Figure 5.
9