Gossen MetraWatt 702 - Manual (Page 19)

GOSSEN METRAWATT GMBH 19
9.3 Measuring Leakage Current
Attention!
!
During leakage current measurement it is essential to ensure
that the DUT is operated at mains voltage. Exposed conductive
parts may be subject to hazardous contact voltage during the
test and may not be touched under any cricumstances. (A
mains shutdown takes place when the leakage current exceeds
approx. 10 mA).
Select the I
xx
measurement and start.
Each time line voltage is
applied to the test socket,
L and N are reversed, if
this function has been se-
lected in the leakage cur-
rent menu (see chapter
9.3 on page 19).
Frequency response is
taken into consideration in
accordance with the dia-
gram to the right when
leakage current is
measured.
9.3.1 Contact Current I
Contact
(probe current, housing leakage current)
Current which flows from housing
parts which are not connected to
the protective conductor via an
external conductive connection
to earth or another part of the
housing. Flow of current via the
protective conductor is excluded
in this case.
The current’s AC component is
measured. The DC component can also be measured by means of indi-
vidual measurement (but not with a test sequence).
9.3.2 Residual Current
ΔI
Sum of instantaneous current values which flow via the L and N conduc-
tors at the device mains connection (also known as differential current).
Residual 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.
Attention: Residual current also includes contact current.
9.3.3 Device Leakage Current I
DL
per DIN VDE 0751
Device leakage current is determined by means of differential current
measurement.
Maximum Allowable Limit Values for Leakage Current in mA
* for devices with a heating power > 3.5 kW
Note 1: Devices which do not have any exposed conductive parts which are
connected to the protective conductor, and which correspond with
I
DL
and, if applicable, I
PL
, e.g. data processing equipment with
shielded power pack
Note 2: Permanently connected devices with protective conductor
Note 3: Portable x-ray devices with mineral insulation
Key
I
Contact
Housing leakage current (probe or contact current)
ΔI Residual current
I
DL
Device leakage current
10 10 2 10 3 10 4 10 5 10 6
+20
0
–20
–40
–60
Frequency (f) in Hz
Relative Magnitude (dB): 20 log
U(
f)
U(
f=10)
μΑ
2
L
N
1
1 Test socket (w/o protective conductor contact)
2 Device housing
Test
Standard I
PE
I
Contact
ΔI
I
DL
NC SFC NC SFC
VDE 0701
-1: 2000 SC I: 3.5
1 mA/kW *
0.5
SCI: 3.5
1 mA/kW *
SC II: 0.5
VDE 0701
-240
0.25
VDE 0702:
2004 SC I: 3.5
1 mA/kW *
0.5 3.5
VDE 0751:
2001
General 0.5
Notes 1 & 3 2.5
Note 2 5.0
SC II 0.1