A 1472, A1579 Leakage current clamp
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4.2 Measuring leakage currents with current clamps
The simplest way of measuring leakage current is the measurement with
leakage current clamps. The measuring principle is shown on Figure 4 and
in Equations 3,4.
Fig.4: Measuring principle of current clamp
– direct and differential method
L
PE
out
R
N
I
U
1
Eq.3
L
N
L
out
R
N
I
I
U
1
)
(
Eq.4
U
out
......................output voltage of current sensor
I
PE
, I
L
, I
N
...............measured currents
R
B
........................load (burden) resistor
N.........................number of turns of current clamp
The main advantage of the measurement with current clamp is that
disconnection of conductors is not needed
– it is a non-contact measuring
method.
In general two methods are used for the leakage currents measurement.
4.2.1 Direct method
The current through one (embraced) conductor is measured in the direct
method.
Fig.5: Leakage current measurement
– direct method
