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INSTRUCTIONS FOR FAULT TRACING AND REPAIR
1 SAFETY INSTRUCTIONS
Repairs may only be carried out by trained experts.
When carrying out fault tracing and repairs, remember that hazardous voltages occur in various
locations on the system. Therefore, switch off the mains switch and unplug the mains plug before
opening the system.
If the unit is operated in open mode, you must be that live parts are exposed.
The following modules and components are connected to the mains voltage and rectified mains
voltage at particular points:
• A1, A4, A5, A6, A11, A12, A15
• C1, C2, C3, C4
• M1, M5
•K1
•Q1
• T3, T4
•X6
• For other cable conductors, see CONNECTION DIAGRAM DTG 405
NOTE! Also remember that, when the unit is open, cooling is no longer effective. For this reason,
do not operate open units at high load for a long time, otherwise components may overheat.
2 PROTECTION AGAINST HAZARDOUS FAULT CURRENTS
After completing every repair, check the electrical safety of the machine. Refer to VDE 0100 and
EN 60974-1 (should be kept with the machine). This manual will not deal with any extracts from
these standards. The following information is not complete and no liability is assumed for the in-
formation given.
2.1 TESTING PROTECTIVE CONDUCTORS
The resistance between the terminal for the protective conductor and conductive components
which may become live under fault conditions must not exceed 0.1 Ω.
Perform the measurements using 25 A AC. The protective conductor will be referred to below as
PE (protective earth).
2.2 INSULATION RESISTANCE
Measure the insulation resistance using a DC voltage of 500 V.
Set up three circuits for testing:
• Input circuit: connect all the phases available in the connecting plug and, if provided, the
neutral conductor.
• PE: protective conductor in the connecting plug.
• Welding circuit, control circuit: interconnect all the connectors provided (X3, X7, X2), Torch
button connection (X5, all pins), and remote-regulator connector (X5, all pins).
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