User Manual

24 GMC-I Messtechnik GmbH
8.5 Measuring Leakage Current
Attention!
!
Measurement with DUT Connected to Line Voltage
It’s absolutely essential to assure that the device under
test is operated with line voltage during performance of
leakage current measurements with the direct or differential
current method. Exposed conductive parts may conduct
dangerous contact touch during testing, and may not
under any circumstances be touched. (Mains power is
disconnected if leakage current exceeds approx.
10 mA.)
Frequency response in
accordance with the
figure to the right is
taken into consider-
ation for all leakage
current measure-
ments (IPE, IT, IE, IP)
(direct, differential,
alternative).
8.5.1 Protective Conductor Current – IPE
Application
Protective conductor current must be measured for protection
class I devices.
Definition of Protective Conductor Current
(direct measurement)
Current which flows through the protective conductor in the case
of housings which are isolated from ground.
Definition of Differential Current
Sum of instantaneous current values which flow via the L and N
conductors at the device mains connection. Differential current is
practically identical to fault current in the event of an error. Fault
current: Current which is caused by an insulation defect, and
which flows via the defective point.
Definition of Alternative Measuring Method
(equivalent leakage current)
Equivalent leakage current is current which flows through the
active conductors of the device which are connected to each
other (L/N), to the protective conductor (SC1) or to the exposed,
conductive parts (SC2).
Differential Current Measuring Method
The device under test is operated with mains power. The sum of
the momentary values of all currents which flow through all active
conductors (L/N) at the mains side of the device connection is
measured. The measurements must be performed with mains
plug polarity in both directions.
Alternative Measuring Method (equivalent leakage current)
A high-impedance power supply is connected between the short-
circuited mains terminals and all exposed metal parts of the hous-
ing (which are connected to one another).
Current which flows over the insulation at the device under test is
measured.
Protective Conductor Current Measuring Method
(direct measurement)
The device under test is operated with mains power. Current
which flows through the PE conductor to earth at the mains side
of the device connection is measured.
Note
Regardless of the currently selected connection type, all
help images and schematic diagrams can be queried for
the selected measuring function.
10 10
2
10
3
10
4
10
5
10
6
+20
0
–20
–40
–60
Frequency (f) in Hz
Relative Magnitude (dB):
U(f)
U(f=10)
Switch
Setting
Meas.
Variant
Measuring functions
Single measurements, rotary switch level: green
Measurements at DUTs with line voltage
I
PE
Direct
Diff.
Alt.
I
PE
Protective conductor current, RMS
I
PE~
AC component
I
PE=
DC component
U
LN
Tes t voltage
I
PE