Theory Of Operation; Inverter Board - Lincoln Electric TOMAHAWK 375 AIR Service Manual

THEORY OF OPERATION

E-3 E-3
FIGURE E.3 - INVERTER BOARD

INVERTER BOARD

This machine is designed on the "single board" con-
cept in which all of the electronic devices are housed
on one printed circuit board.
The single phase input voltage (208-230VAC) is con-
nected to the Tomahawk inverter board via an input
®
cord and power switch located on the back of the
machine. The input power is applied first to a filter cir-
cuit and then to a pre-charge relay circuit. This pre-
charge circuit limits the in-rush current through the
input rectifier so that the input capacitors are charged
in a controlled manner. When the pre-charge
sequence is completed the pre-charge relay closes
connecting full input power to the filter capacitors. This
rectified and filtered DC voltage (325VDC @ 230VAC
input) is used to power the half-wave bridge circuit and
generate several DC voltages for the on board CPU
and electronics.
NOTE: Unshaded areas of Block Logic
Diagram are the subject of discussion
TOMAHAWK ® 375 AIR