300ACDC
2
INTRODUCTION
2 – 3
5
Description
The Thermal Arc
TM
Model 300ACDC is a self contained single/three -phase AC/DC arc welding power
source with Constant Current (CC) output characteristics. This unit is equipped with a Digital Volt/Amperage
Meter, gas control valve, built in Sloper and Pulser, lift arc starter, and high-frequency arc starter for use with
Gas Tungsten Arc Welding (GTAW), Gas Tungsten Arc Welding-Pulsed (GTAW-P) Gas Tungsten Arc Weld-
ing-Sloped (GTAW-S), and Shielded Metal Arc Welding (SMAW) processes. The power source is totally
enclosed in an impact resistant, flame retardant and non-conductive plastic case.
NOTE
Volt-Ampere curves show the maximum Voltage and Amperage output capabilities of the welding power
source. Curves of other settings will fall between the curves shown.
Figure 2-1: Model 300ACDC Volt-Ampere curve
6
Functional Block Diagrams
Figure 2-1 illustrates the functional block diagram of the 300ACDC-power supply.
Figure 2-2: 300ACDC Model Functional Block Diagram
300A
5A
(A)
(V)
OCV
300A
25A
(A)
(V)
OCV
10V
300A
(A)
(V)
OCV
5A
STICK Process
LIFT TIG Process
HF TIG Process
Main
Circuit
Switch
Filter
Input
Diode
Primary
Capacitor
DC Power
Voltage
Sensor
IGBT
Inverter
Thermal
Detector
To each control circuit
+/-15VDC +18VDC
+24VDC +5VDC
Trouble
Sensing
Circuit
Drive
Circuit
Torch Control
Connection
(CON1)
circuit
Current
Adjustment
Reference
Adjustment &
Mode select Switches
Panel Circuit Board
Sequence
Control
Thermal
Sensor
Circuit
Main
Transformer
(PCB14)
Output
Diodes
HF-UNIT
Control
Circuit
Stick Mode
VRD
Sensing
Circuit
Lift Tig Mode
Output Short
Sensing
Circuit
Coupling
High
Coil
Frequency
Unit
Fan Control
Circuit
Gas Control
Circuit
Fan
Solenoid
Hall Current
Transformer
(HCT1)
Output
Inductor
Thermal
Detector
Input
Power
Drive
DC Power
Circuit
To each control circuit
+/-12VDC +15VDC
Secondary
IGBT
Inverter
Primary
Current
Sensor
Summary of Contents for ARCMASTER 300 AC/DC
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