Fronius WTU 307 Bedienungsanleitung Seite 20

Fig. 1 WTU 307 power source, shown with welding cables fitted
(optional remote-control connection)
The machines of this series stand out for their
- big energy savings
- low open-circuit voltage (5V)
- absolute operational reliability and safety
- excellent welding quality
Other advantages
- welding current can be continuously remote-controlled
- continuously adjustable arc-force, for adjusting the welding characteri-
stics
- current stabilisation: the pre-set welding-current value is kept constant
V
by the control electronics, regardless of mains voltage fluctuations and
the lengths of the welding and mains cables
50
40
30
CONSTRUCTION AND TECHNICAL
20
DESRIPTION
10
5
Housing
50 100
- Sheet steel, baked enamel finish resp. powder coated
- The watertight electronics case is welded directly onto the main case
(Faraday cage)
- Large wheels and fold-away carrying handles make these units ideally
suitable for easy transport inside the factory as well as for use on
building sites. (Single-hook crane hoisting point can be retrofitted)
Transformer
- Three-phase current model, consisting of iron core, primary, secondary
and auxiliary windings.
- The auxiliary windings serve to synchronise the thyristor igni-
tion impulses and as the power supply for the electronics.
- The entire transformer has been dipcoated in impregnating varnish and
oven-dried, and conforms to insulation category H (= 180°C).
150 200
R é gulateur
0 5 10
dynamique
Rectifier
- The silicon rectifier stack is constructed as a fully controlled three-phase
bridge, and is fitted with easy-to-replace screw-in diodes and thyristors.
The inductance serves to
- smooth out the direct current
- limit the speed of current rise at the moment of drop transfer (reduces
spattering, forms softer arc).
Control electronics
- The unit is attached to the front control panel, which in turn is fastened
to the front panel of the machine by means of four screws.
- Operating errors are unlikely, thanks to the clear labelling on the front
control panel
- The power supply connection between the power source and the control
unit is via one central multipole plug-in connector.
- Modules with and without r.c. connection are interchangeable
- Changes in the mains voltage, arc length and other influencing factors
usually result in changes in the welding current. The built-in control
ensures that the welding current, which apart from minor deviations is
identical to the set current, remains constant (set current = scale value
set on the machine).
Cooling system
- Forced-air cooling by means of fan
- The fan starts running as soon as the main switch
on.
- The well thought-out arrangement of transformer, rectifier and induc-
tance gives an optimum cooling effect, thus helping the machine to keep
to its specified duty cycle.
Heat protection
- If the duty cycle is exceeded, a thermostat built in to the inductance
switches the machine off on the secondary side.
- The ventilator continues to run.
- Once the temperature has dropped sufficiently, the machine is automa-
tically rendered operational once more.
Power socket, 230V / 2kVA (not fitted as standard)
- Can be fitted to the rear of the power source on request
POSSIBLE APPLICATION SET-UPS
A
Fig. 2 WTU 307 as a manual electrode welding unit with a manual remote-control unit and
welding cables
Fig. 3 WTU 307 as a TIG welding unit with a manual remote-control unit, TIG torch set
and earthing cable
6
has been switched