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1.1 GENERAL
The ESAB 350mpi is a high performance constant
voltage (CV) and constant current (CC) inverter power
source designed to provide multi-process welding ca-
pabilities with dependability and ease of use. The
ESAB 350mpi is a self-contained unit which will pro-
duce power for Gas Metal Arc (MIG), Gas Tungsten
Arc (TIG) and Shielded Metal Arc (Stick) welding
without the use of optional apparatus.
For MIG (CV) welding, the ESAB 350mpi supports
welding a wide selection of ferrous and non-ferrous
alloys by utilizing Fixed Slope and inductance controls.
A special "Touch Tig" circuit eliminates the need for
high frequency or "scratch" starting when using the
TIG (CC) welding process. This feature provides smooth
starts without contaminating the electrode or the work.
The Stick (CC) welding mode provides adequate open
circuit voltage (70 V dc) for easy starts and re-starts as
well as an adjustable arc force which controls arc
penetration and wetting action.
The "Auto Fan" feature operates the cooling fan only
when the contactor is energized or when the internal
temperature exceeds the safe operating level. During
normal operation, the fan shuts down about 5 minutes
after the contactor disengages.
1.2 DUTY CYCLE
The ESAB 350mpi power source will operate on a 60%
duty cycle with a load of 350 amperes at 34 V dc (with
3-phase input). Duty cycle is defined as the ratio of
operating time to total time. Ratings are based on a 10-
minute cycle. The 60% duty cycle rating means that the
350 ampere, 34 volt rated load can be applied for a total
of 6 minutes and shut off for a total of 4 minutes in a 10-
minute period. If the welding current (or voltage) is
reduced, the duty cycle increases. Conversely, if the
welding current (or voltage) is increased, the duty cycle
will decrease. Refer to Table 1-1 and Figure 1-2.
1.3 VOLT-AMPERE CURVES
Figure 1-2 illustrates the static volt-ampere character-
istics for the power source in the MIG (CV), TIG (CC),
and Stick (CC) modes. The slant of these curves is
referred to as the slope and is generally defined as the
voltage drop per 100 amperes of current rise. These
curves show the output voltage available at any given
output current between the minimum and maximum
settings of the output control. Values for other settings
fall between the minimum and maximum curves.
Table 1-1. Technical Specifications
RATED OUTPUT
100% Duty Cycle (3-phase input) 300 A @ 32 V dc
100% Duty Cycle (1-phase input) 225 A @ 29 V dc
60% Duty cycle (3-phase input) 350 A @ 34 V dc
Open-circuit Voltage (max) 70 V dc
PHYSICAL
Height 16.4 in. (417 mm)
Width 11.5 in. (292 mm)
Depth 29.8 in. (757 mm)
Weight 101 lbs (39 kg)
INPUT VOLTAGE AND CURRENT @ RATED 60% DUTY CYCLE LOAD
230/460 V ac models 3-phase 50/25 amps
1-phase 50/38
SECTION 1 DESCRIPTION
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