General Principles - Telwin LINEAR 350I Bedienungsanleitung

generator; an exception is the negative pole (-) for electrodes with acid coating.
5.3.2.1 Connection of the electrode-holder clamp welding cable
Bring a special clamp on the clamp used to tighten the exposed part of the electrode.
Connect this cable to the clamp with the symbol (+) (Fig. B-2).
5.3.2.2 Connecting the welding current return cable
- Connect the cable to the piece to be welded or the metal bench on which the
workpiece is placed, as close as possible to the joint being worked. Connect this
cable to the clamp with the symbol (-) (Fig. B-3).
6. MMA WELDING: PROCESS DESCRIPTION
6.1 GENERAL PRINCIPLES
- It is essential to follow the recommendations provided by the manufacturer on the
electrode packaging which indicates the correct electrode polarity and relative rated
current.
- Welding current is regulated to suit the diameter of the electrode being used and the
type of soldering to be performed; an example of the currents used for the various
electrode diameters can be seen below:
Ø Electrode (mm)
1.6
2.0
2.5
3.2
4.0
5.0
6.0
8.0
- One can see that for the same diameter electrode, high levels of current will be
used for flat welding, whilst lower current levels will be used for vertical or overhead
welding.
- The mechanical characteristics of the welded joint are determined by the intensity
of the selected current and also other welding parameters such as the length of the
arc, the operating speed and position, the diameter and quality of the electrodes
(to ensure correct conservation, use special packaging or containers to store and
protect the electrodes against humidity).
ATTENTION:
Instability of the arc due to the composition of the electrode can occur,
depending on the brand, type and thickness of the electrode coatings.
6.2 PROCEDURE
- Keeping the mask IN FRONT OF YOUR FACE, rub the tip of the electrode on the
piece to be welded, moving as if striking a match; this is the most correct method for
igniting the arc.
ATTENTION: DO NOT TAP the electrode against the workpiece, which could
damage the coating and make arc striking difficult.
- As soon as the arc has struck, try to keep the electrode at a distance from the
workpiece that is equivalent to the diameter of the electrode being used, and keep
this distance as constant as possible while welding; remember that the electrode
angle while moving forward must be approx. 20-30 degrees.
- At the end of the welding seam, take the electrode end slightly back as to the forward
direction, above the crater to fill it, then quickly lift the electrode from the weld pool
to switch off the arc (Aspects of the welding seam - FIG. F).
7. MAINTENANCE
ATTENTION! BEFORE CARRYING OUT MAINTENANCE WORK,
MAKE SURE THAT THE WELDING MACHINE IS SWITCHED OFF AND
DISCONNECTED FROM THE POWER SUPPLY.
EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE OPERATIONS SHOULD BE CARRIED
OUT ONLY AND EXCLUSIVELY BY SKILLED OR AUTHORISED ELECTRICAL-
MECHANICAL TECHNICIANS AND IN COMPLIANCE WITH THE TECHNICAL
STANDARD IEC/EN 60974-4.
ATTENTION! BEFORE REMOVING THE WELDING MACHINE PANELS
AND GOING INSIDE, MAKE SURE THE WELDING MACHINE IS
SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER
SUPPLY.
If checks are carried out while the inside of the welding machine is live, this
could cause a serious electric shock due to direct contact with live parts and/or
injury due to direct contact with moving units.
- Periodically, and however frequently, based on the use and dust in the environment,
inspect inside the welding machine and remove the dust deposited on the
transformer, reactance and rectifier using a dry compressed air jet (maximum 10
bar).
- Avoid directing the compressed air jet on the electronic cards; clean them with a very
soft brush or appropriate solvents.
- Also check the electrical connections are well-tightened and the cabling has no
insulation damage.
- Having completed these operations, re-assemble the welding machine panels by
tightening the fastening screws completely.
- Strictly avoid carrying out any welding operations with the welding machine open.
- Having carried out maintenance and repairs, restore the connections and wiring
as they were originally, taking care they do not obstruct any moving parts or parts
which can reach high temperatures. Wrap all the conductors as they were originally,
taking care to keep the high voltage primary connections clearly separated from the
secondary low voltage connections.
Use all the washers and original screws to close the framework up again.
8. TROUBLESHOOTING
IN THE EVENT OF UNSATISFACTORY OPERATION, AND BEFORE CARRYING
OUT MORE SYSTEMATIC CHECKS OR CONTACTING YOUR SUPPORT CENTRE,
CHECK THAT:
- The welding current, adjusted using the potentiometer with reference to the
graduated scale in amperes, is adequate for the diameter and type of electrode
used.
- With the main switch "ON", the relevant light is on; on the contrary, the defect
normally lies on the power line (cables, socket and/or plug, fuses, etc.).
Welding current (A)
Min. Max.
30 50
40 80
60 110
90 140
120 180
170 250
230 350
320 500
- The yellow led is not on, signalling intervention of the safety thermal switch for over
or undervoltage or short circuit.
- Ensure you have observed the nominal duty cycle ratio; in the event of intervention
of the thermostatic protection, wait for the welding machine to cool naturally, check
the fan is working.
- Check the line voltage: if the value is too high or too low, the welding machine
remains blocked.
- Check there is no short circuit on welding machine output: in this case, proceed to
eliminate the problem.
- The welding circuit connections are carried out correctly, particularly the earth cable
clamp is actually connected to the piece and without inter-positioning insulating
materials (e.g. paint).
- The protection gas used is correct and the right amount.
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