Lincoln Electric IDEALARC DC-1000 Service Manual page 30

E-2
FIGURE E.2 - INPUT LINE VOLTAGE, CONTACTOR, AND MAIN TRANSFORMER
GENERAL DESCRIPTION
The DC 1000 is an SCR - controlled DC power source.
It is designed to be controlled with a single range
potentiometer output control. It can be used for sub-
merged arc or open arc automatic and semiautomatic
welding.
THEORY OF OPERATION
INPUT LINE VOLTAGE, CONTACTOR,
AND MAIN TRANSFORMER
The desired three phase power is connected to the
DC-1000 through an Input Contactor located in the
input box at the rear of the machine. Two phases of the
input lines are also connected to the Control
Transformer which supplies power to the Contactor
Hold-In Circuit. The Contactor Hold-In Circuit will dis-
able the Input Contactor if the DC-1000 is overloaded
or overheated.
A Reconnect Panel allows the user to configure the
machine for the desired input voltage. This AC input
voltage is applied to the primary of the Main
Transformer. The transformer changes the high volt-
age, low current input power to a low voltage, high cur-
rent output. The finishes or "neutrals" of the main sec-
ondary coils are connected together and the six starts
of the secondary windings are connected to the rectifi-
er assembly. In addition, the main transformer also has
an isolated 115 VAC auxiliary winding that supplies 115
VAC to operate the cooling fan and offers 8 amps of
auxiliary power to operate wire feeding equipment. The
three 75 VAC phase angle windings are also housed in
the Main Transformer assembly. These windings pro-
vide power and "timing" to the Firing Board.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
IDEALARC ® DC-1000
E-2