Tweco 400 MST Arc Master - Manual (Page 18)

400MST
2
INTRODUCTION AND DESCRIPTION
2 – 3
NOTE
These units are equipped with a three-conductor
with earth power cable that is connected at the
welding power source end for single or three-phase
electrical input power.
Do not connect an input (WHITE, BLACK or RED)
conductor to the ground terminal.
Do not connect the ground (GREEN) conductor to
an input line terminal.
Refer to Figure 2-3 and:
1. Connect end of ground (GREEN) conductor to
a suitable ground. Use a grounding method
that complies with all applicable electrical
codes.
2. Connect ends of line 1 (BLACK) and line 2
(WHITE) and line 3 (RED) input conductors to
a de-energized line disconnect switch.
3. Use Table 1 and Table 2 as a guide to select
line fuses for the disconnect switch.
NOTE
For Single-Phase operation connect the GREEN,
BLACK and WHITE input conductors. Insulate the
RED Conductor, it is not used for Single-phase
operation.
Table 2-1: Electrical Input Connections
NOTE
Fuse size is based on not more than 200 percent of
the rated input amperage of the welding power
source (Based on Article 630, National Electrical
Code).
Figure 2-3: Electrical input connections
5.2 Input Power
Each unit incorporates an INRUSH circuit and input
voltage sensing circuit. When the MAIN SWITCH is
turned on, the inrush circuit provides a pre-charg-
ing of the input capacitors. At this point, the Bus
Voltages are checked and the welder is enabled
after the input capacitors have charged to full
operating voltage (after approximately 5 seconds).
NOTE
Note the available input power. Damage to the
welder could occur if 575VAC or higher is applied.
The following 208-230/460V Primary Current rec-
ommendations are required to obtain the maximum
welding current and duty cycle from this welding
equipment:
Table 2-2: Primary Current Circuit sizes to achieve max-
imum current
Input Voltage Fuse Size
208 VAC 100 Amps
230 VAC 75 Amps
460 VAC 50 Amps
Model
Primary
Supply
Lead Size
Minimum
Primary
Current
Circuit Size
(Vin/Amps)
Current & Duty Cycle
MIG TIG STICK
400MST
8/4 AWG
minimum
(Factory
Fitted)
3φ
208/63
400A@
25%
- -
230/57 - -
460/29 - -
208/49 -
400A@
25%
-
230/44 - -
460/22 - -
208/67 - -
400A@
25%
230/61 - -
460/31 - -
8/3 AWG
minimum
1φ
208/88 300A@
25%
- -
230/79 - -
208/67 - 300A@
25%
-
230/60 - -
208/97 - - 300A@
25% 230/87 - -