18
GOSSEN-METRAWATT
6
Testing Devices per DIN VDE 0702:1995
6.1
General
The following periodic tests are required according to DIN VDE 0702:
•
Protective conductor resistance measurement
•
Insulation resistance measurement
•
Equivalent leakage current
•
Contact current measurement
•
Residual current measurement (with METRATESTER
â
5/5-F only)
Note!
+
If any doubts exist concerning the performance of an insulation resistance
measurement, a differential current measurement can be performed in its place.
For example, this may be the case with electronic devices and data processing
equipment, or safety class I devices if it is assured that all components which are
charged with line voltage are covered by this measurement.
This measurement may only be performed after the protective conductor at the DUT
has been tested.
The device under test must be plugged into the
mains outlet
at the
METRATESTER
â
5/5-F test instrument for measurement of residual current.
6.2
Measuring Protective Conductor Resistance
The measurement of protective conductor resistance is of course not possible for devices
which are not equipped with a protective conductor (e.g. safety class II and III devices).
➭
Connect the device under test as described in chapter 4.4, page 11.
➭
Set the measuring range selector switch to the “20
W
” position.
➭
Read the measured value in “
W
” from the LCD.
➭
Move the cable at the DUT during the measurement, section by section over its entire
length, in order to locate interruptions.
Protective conductor resistance may not exceed the following values:
Maximum Allowable Protective Conductor Resistance Values Depending upon Cable Length
The table is also valid for cable reels and extension cables. The following applies to longer
cable lengths: additional 0.1
W
per additional 7.50 m cable length, no maximum length limit,
independent of conductor cross-section.
Attention!
!
The alligator clip (3) must make good contact with the housing of the device under
test!
The connector cable must be moved during measurement, section by section over
its entire length – for permanently installed devices only in so far as the cable is ac-
cessible during repair, modification or testing. If the resistance value fluctuates during
this manual test which is essential for continuity testing, it must be assumed that the
protective conductor is damaged, or that one of its connection points is defective.
Defects of this type must be corrected before any further tests are performed.
Length to [m]
5
12. 5
20
27.5
35
42.5
50
more than 50
Max. resistance [
W
]
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0