ESAB MIGMASTER 250 - Operating Procedures and Safety

33
Fig. 4.2.5 Duty Cycle Curves
4.2.6 VOLT/AMPERE CURVES (Figure 4.2.6)
The Volt/Ampere curves show the output Voltage available
at any given output current for the various Voltage Selector
positions in each range low, medium, and high.
The actual operating point of load Voltage and Current is
determined by type of process, electrode, shield gas, wire
feed speed, and operating technique.
4.3 OPERATING PROCEDURES
4.3.1 OPERATING SAFETY PRECAUTIONS
Comply with all ventilation, re and other safety require-
ments for arc welding as established in the SAFETY Section
at the front of this manual.
Also remember the following:
A. Because of the radiant energy of the welding arc
and the possibility of drawing an arc before the
helmet is lowered over the face, the operator should
wear ash goggles with lter lenses under his helmet.
The helmet lter plated should be shade number
11 (nonferrous) or 12 (ferrous). All those viewing the
arc should use helmets with lter plates, as well as
ash goggles. Nearby personnel should wear ash
goggles.
B. The radiant energy of the arc can decompose chlori-
nated solvent vapors, such as trichloroethylene and
perchlorethylene, to form phosgene, even when
these vapors are present in low concentrations. DO
NOT weld where chlorinated solvents are present in
atmospheres in or around the arc.
C. DO NOT touch the electrode, nozzle or metal parts in
contact with them when power in ON: all are electri-
cally energized (HOT) and can cause a possibly fatal
shock. DO NOT allow electrode to touch grounded
metal: it will create an arc ash that can injure eyes.
It may also start a re or cause other damage.
D. When working in a conned space, be sure it is
safe to enter. The conned space should be tested
for adequate oxygen (at least 19%) with an approved
oxygen measuring instrument. The conned space
should not contain toxic concentrations of fumes or
gases. If this cannot be determined, the
operator should wear an approved air supplied
breathing apparatus.
Avoid gas leaks in a conned space, as the leaked gas can
dangerously reduce oxygen concentration in the breath-
ing air.
DO NOT bring gas cylinders into conned spaces.
When leaving a conned space, shut OFF gas supply at the
source to prevent gas from leaking into the space, if the
switch is accidently kept depressed. Check the breathing
atmosphere in the conned space to be sure it is safe to
reenter.
DUTY CYCLE
HIGH
MED.
LOW
LOAD LINE
VOLTS = 14+ (.05 x AMPS)
50
100
150
200
250
AMPERES
SECTION 4 OPERATION