Maintenance and testing
Test
Item No.: 099-000155-EWM01
59
7.3.6
Measuring the leakage current (protective conductor and contact current)
Note: Even if the leakage current measurement according to the standard is only an alternative to the
insulation resistance measurement, EWM recommends always performing both measurements,
especially following repair work. The leakage current is based for the greater part on a physical effect
other than the insulation resistance. For this reason, it may not be possible to uncover a dangerous
leakage current using the insulation resistance measurement.
These measurements cannot be performed with a normal multimeter. Even test devices for VDE 0702
(especially older devices) are generally only intended for 50/60 Hz. With inverter welding machines,
however, significantly higher frequencies occur, which can interfere with some measuring devices, and
result in others measuring the frequency incorrectly.
A test device must meet the requirements of VDE 0404-2. For the frequency response measurement,
please refer to DIN EN 61010-1 Appendix A – Measuring circuit A1.
NOTE
For these measurements, the welding machine must be switched on and supplying open
circuit voltage!
1. Protective conductor current: < 5 mA
2. Leakage current from the welding sockets separately to PE: < 10 mA
7.3.7
Measurement of protective conductor resistance
Measure between the plug earthed contact and accessible live parts, e.g. casing screws.
During the measurement, the connection lead must be moved across the entire length, especially near
the casing and plug inlet points. This should uncover any interruptions in the protective conductor. All
conductive parts of the casing accessible from outside should also be tested to ensure a correct PE
connection for safety class I.
The resistance must not exceed a mains connection lead 0.3
Ω
up to 5m in length. For longer leads, the
permissible value increases by 0.1
Ω
per 7.5m of lead. The maximum permissible value is 1
Ω
.
7.3.8
Functional test of the welding machine
Safety devices, selector switches and command units (if fitted) and the entire machine or the entire
system for arc welding, must be functioning perfectly.
1. Main switch
2. Emergency stop devices
3. Voltage reducing device
4. Gas solenoid valve
5. Message and control lamps
7.3.9
Documentation of the test
The test report must contain:
• the designation of the tested welding equipment,
• the date of the test,
• the test results,
• the signature, name of technician and the relevant institution,
• the name of the test equipment.
A label with the date of the test must be affixed to the welding machine to show that the test has been
passed.
