Input Power; High Frequency Introduction - Thermal Arc Arcmaster 400 MST Operating Manual

3.05 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-charging of the input capacitors. SCR's in the Power Control Assembly
(PCA) will turn ON after the input capacitors have charged to full operating voltage (after approximately 5
seconds).
Note the available input power. Damage to the PCA could occur if 460VAC or higher is applied.
The following 208-230/460V Primary Current recommendations are required to obtain the maximum
welding current and duty cycle from this welding equipment:
Primary Supply
Model
(Factory Fitted)
4 mm sq / 4
ArcMaster
400 MST
Table 2 – Primary Current Circuit sizes to achieve maximum current
The ARC MASTER 400MST is designed for use with a generator as an input power source. Contact an
accredited Thermal Arc service agent for the proper sizing and set-up recommendations of a generator power
source system. As a general rule, depending on the type of generator used, the generator capacity should be
twice the maximum rating of the welder.

3.06 High Frequency Introduction

The importance of correct installation of high frequency welding equipment cannot be over-emphasized.
Interference due to high frequency initiated or stabilized arc is almost invariably traced to improper installation.
The following information is intended as a guide for personnel installing high frequency welding machines.
Explosives
The high frequency section of this machine has an output similar to a radio transmitter. The machine
should NOT be used in the vicinity of blasting operations due to the danger of premature firing.
Computers
It is also possible that operation close to computer installations may cause computer malfunction.
Minimum Primary
Lead Size Current Circuit Size
(Vin/Amps)
minimum
Note
MIG
400/33 400A @ 25%
400/26 -
400/35 -
WARNING
17
Current & Duty Cycle
TIG STICK
-
400A @ 25%
- 400A @ 25%
-
-