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THEORY OF OPERATION
E-4
E-4
SQUARE WAVE TIG 355
HIGH VOLTAGE/
HIGH FREQUENCY CIRCUIT
The control board signals the power board to pass the
115VAC voltage through the feed – thru board to the
primary of the high voltage tarnsformer. The sec-
ondary of the high voltage transformer is coupled to a
spark gap generator and also to the high frequency
transformer. The high frequency transformer transfers
the high frequency “spark” to the electrode terminal.
FIGURE E.4 – HIGH VOLTAGE/HIGH FREQUENCY CIRCUIT
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.
HIGH VOLTAGE
TRANSFORMER
CIRCUIT
REMOTE
RECEPTACLE
GAS/WATER
SOLENOIDS
FANS
115VAC
RECEPTACLE
INPUT
CONTACTOR
R
E
C
O
N
N
E
C
T
POWER
FACTOR
CAPACITORS
FEED - THRU
BOARD
CONTROL
BOARD
POWER
BOARD
SNUBBER
BOARD
MAIN
TRANSFORMER
AC
AC
DC-
DC+
POLARITY
SWITCH
SHUNT
C
H
O
K
E
BY-PASS
BOARDS
WORK
ELECTRODE
HI-FREQ
TRANSFORMER
PILOT
TRANSFORMER
START/
STOP
PANEL
SWITCHES
UPPER
CONTROL
PANEL
LOWER
CONTROL
PANEL
DISPLAY
BOARD
STATUS
BOARD
ELECTRODE SENSE
HIGH FREQUENCY SPARK
115VAC
INTERLOCK
HI-FREQ AND GAS/WATER
115VAC -
115VAC
CONTROL TRANSFORMER
INTERLOCK
ELECTRODE
SENSE
REMOTE
COMMANDS
GATE COMMANDS
HI-FREQ/ WATER/GAS
COMMANDS
INTERLOCK
115VAC
SCR
TRIGGER
15VDC
115VAC