Praxair SELECT-400, Operating Instructions Manual

SEQUENCE OF OPERATIONS

WELDING WITH SHIELDING GAS

For this type of welding, you must use a wire feeder; PRAXAIR SOLDADURA S.L. markets a suitable model for this machine, the
MIG-44 code 246.068.4. This wire feeder has a powerful four roller wire feed system. The machine is connected to the wire
feeder by an extension cord with standardised lengths of 5, 10, 15, 25 and 50m.
There are two types of extension cords available: a standard extension cord and a single cable one. 

The machines leave

the

factory with the gas connection for the single cable type

. When standard extension cords are used, remove the right

side panel and change the gas connection, moving the hose from the centralised connection to the rapid outlet located
on the front panel.
The single cable extension cord is connected to the machine front panel by means of a centralised EURO type power
connector and a control connector; to the standard extension cords, connect the rapid power connector, the gas
adapter connector to the rapid outlet and connect the control connector. In both cases, the other end of the extension
cord is connected to the rear part of the wire feeder. The shielding gas cylinder is connected to the machine back panel by
means of the gas hose supplied. The cylinder must have a flowmeter. PRAXAIR SOLDADURA S.L. markets kits for the different
torches, including a flowmeter model R54-CA, code 232.246.0.
Select the correct flow for the type of work to be performed.
The MIG-44 wire feeder may simply rest on the machine cover or a rotary support may be used. The support is inserted into
the hole on the machine cover and the feeder is fixed to this support by four screws; the feeder panels must be removed to
access these screws; this support will enable the feeder to turn, and it can be tilted so that the torch is always in the air,
without being dragged along the floor, so avoiding short circuits in its hoses. The code for this torch is 245.769.6, it has a
modern design and is made of zinc plated steel.
The torch is connected to the wire feeder by means of a centralised EURO type

connection.

Optionally this machine can operate with water cooled torches, for this COOLING UNIT R-7, code 241.897.5,  needs to be
installed on the rear of the machine. When the cooling unit is installed, the cylinder support must be moved to the left and
repositioned in the holes provided.
There is a platform on the rear of the machine to hold the gas cylinder which is secured to the machine by means of an
easily secured steel chain.
Place the appropriate wire reel on the wire feeder, and select the correct roller for this type of wire and then activate the
rapid feed until the wire protrudes from the torch tip.
The welding current is selected by two selector switches located on the machine front panel: one 3 position switch (S1) for
Coarse work and one 10 position switch (S2) for fine work. A combination of these two selector switches gives 30 settings for
regulating the current to suit the work.

WARNING! : Do not change these selector switches whilst welding, this could damage them.

Connect the earth cable to one of the two connectors located on the bottom left of the front panel; one of these
connectors is for medium inductance (small wave) and the other is for high inductance (large wave). Select the right one
for your work.
Press the line breaker on the front panel, marked as (0-I) and commence welding.

OUTPUT

The machine’s output is defined by cycles indicated as a % and referring to a 10 min time interval during which the
machine can give the specified current. To obtain an optimum performance, always use short cables whenever possible,
these should have no loops and should be of the appropriate section: do not use power cables of less than 6 mm

2

 nor

welding cables of less than 50 mm

2 

(SELECT-400),16mm

2

/70 mm

2

 (SELECT-600). Always use original connectors supplied by the

machine manufacturer, PRAXAIR SOLDADURA S.L. Make sure that these are remain free from grease and other dirt and,
when making the connection, turn the connector until the correct electric contact is made.

CHARACTERISTICS

The SELECT 400/600 unit is designed for general use, and is suitable for both light and heavy duty welding work. It has an
excellent characteristic for “short arc” and “spray arc” welding.
The current intensity generated is of constant potential, which is appropriate for MIG-MAG welding processes. The main
transformer (TP) is equipped with thermal protection and is cooled by a noiseless ventilator.
The two handles on the front panel and the four wheels on the base (the front two are swivel wheels) make the unit easy to
transport.