Tweco Thermal Arc TA 500 - Manual (Page 18)

General Information 1-4 Manual No 0-0470
Current Control
The desired cutting current is set with the control knob, lo-
cated to the left of the ammeter, on the Control panel. A
control circuit in the Power Supply stabilizes the cutting cur-
rent against fluctuations due to changes in line voltages,
material thickness, torch standoff and travel speed. Chang-
ing the saturating current in the reactor changes the amount
of AC power supplied to the main bridge rectifier. The satu-
rating current is controlled by SCR’s which are in turn con-
trolled by a printed circuit card which compares the actual
cutting current to the current selector potentiometer setting.
Coolant Recirculator
When the Power Supply is turned on the Coolant
Recirculator starts circulating coolant through the torch
and back to the Recirculator through the radiators, res-
ervoir, filter and pump. The Recirculator is a closed
loop system and includes a deionizer assembly which
maintains the resistivity of the coolant.