Tweco 201 ts Thermal Arc - Manual (Page 29)

OPERATION THERMAL ARC 201 TS
Manual 0-5149 4-3 Operation
J. ON/OFF Switch (located on rear panel not shown)
This switch controls the Mains Supply Voltage to the
Power Source.
4.02 Welding Current Control
Explanation
32 Amp Outlet
The mains power 32 Amp circuit breaker or fuse should
not trip at this Weld Current value when STICK welding.
The environmental conditions that may cause the mains
power 32 Amp circuit breaker or fuse to trip are:
a) High ambient temperature
b) Worn parts in circuit breaker
c) Using an extension cable
d) Low line mains power voltage
Output Scale for 110V
The inside number scale identifies the available
output weld current for STICK or LIFT TIG weld modes.
STICK Mode: Identifies the STICK weld point for
32 Amp outlet.
Exceeding these points will cause nui-
sance tripping of the circuit breaker or
fuse.
Nuisance tripping should not occur on a 16 Amp outlet.
Output Scale for 230V
The outside number scale identifies the available out-
put weld current for STICK or LIFT TIG/HF TIG weld
modes.
Nuisance tripping should not occur on a 32A 230V outlet
for both STICK & LIFT TIG/HF TIG Modes.
Art # A-10147
32 Amp Outlet
Output Scale for 110V
Output Scale for 230V
32A OUTLET STICK
TIG
230V
110V
TIG/STICK
32A OUTLET
16A OUTLET
Figure 4-2: Current Control
4.03 STICK (MMA) Electrode Polarity
Stick electrodes are generally connected to the "+" Posi-
tive Output Terminal and the work lead to the "−" Negative
Output Terminal but if in doubt consult the electrode
manufacturers literature for further information.
4.04 Effects of Stick Welding Various
Materials
High Tensile and Alloy Steels
The two most prominent effects of welding these steels
are the formation of a hardened zone in the weld area,
and, if suitable precautions are not taken, the occurrence
in this zone of under-bead cracks. Hardened zone and
under-bead cracks in the weld area may be reduced by
using the correct electrodes, preheating, using higher
current settings, using larger electrodes sizes, short
runs for larger electrode deposits or tempering in a
furnace.
Manganese Steels
The effect on manganese steel of slow cooling from
high temperatures is to embrittle it. For this reason it
is absolutely essential to keep manganese steel cool
during welding by quenching after each weld or skip
welding to distribute the heat.
Cast Iron
Most types of cast iron, except white iron, are weldable.
White iron, because of its extreme brittleness, gener-
ally cracks when attempts are made to weld it. Trouble
may also be experienced when welding white-heart
malleable, due to the porosity caused by gas held in
this type of iron.
Copper and Alloys
The most important factor is the high rate of heat
conductivity of copper, making pre-heating of heavy
sections necessary to give proper fusion of weld and
base metal.
Types of Electrodes
Arc Welding electrodes are classified into a number of
groups depending on their applications. There are a
great number of electrodes used for specialized indus-
trial purposes which are not of particular interest for ev-
eryday general work. These include some low hydrogen
types for high tensile steel, cellulose types for welding
large diameter pipes, etc The range of electrodes dealt
with in this publication will cover the vast majority of
applications likely to be encountered; are all easy to use.