Tweco 251 Thermal Arc Fabricator - Manual (Page 42)

FABRICATOR 251
OPERATION 4-4 Manual No. 0-4847
0
100
200
300
400
500
600
700
800
900
25 50 75 100 125 150 175 200 225 250 275 300 325
Current (Amps)
Wi
re Speed (IPM)
(.030 - AL)(.035 - AL)
(.047 - AL)
Art # A-07453
ALUMINUM
Figure 4-5: Aluminum - AMP to IPM Conversion
Thermal Overload
The critical components for thermal protection are the rectifier stack and the transformer, which are fitted with
thermal overload cut out devices. If the overload is activated then the machine should be left to cool for approxi-
mately 15 minutes before resuming welding. If the Power Source is operated within its duty cycle, the thermal
overload will not activate. Refer to section 2.09 for an explanation of duty cycle and section 2.10 for the power
supply specifications.
Wirespeed Control
The Wirespeed Control knob controls the welding current via the electrode wire feed rate, i.e. the speed of the wire
feed motor.
Coarse Voltage Control Switch
The Coarse Voltage Control sets the voltage level to the welding terminals as it is rotated in either direction. Clock
wise to increase.
Fine Voltage Control Switch
The Fine Voltage Control switch increases the voltage (in smaller increments than the Coarse switch) as it is
rotated in either direction. Clock wise to increase.
CAUTION
The Coarse & Fine Voltage Control switches MUST NOT BE SWITCHED during the welding process.