Control of welding current, 1, b.2 and b, Operation – Lincoln Electric CLASSIC III SVM 137-A User Manual

Page 20: Caution, Current range selector fine current adjustment, Figure b.2 – current controls

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CONTROL OF WELDING CURRENT

• DO NOT turn the CURRENT RANGE SELECTOR

while welding because the current may arc between
the contacts and damage the switch.

• DO NOT attempt to set the CURRENT RANGE

SELECTOR between the five points designated on
the nameplate.

See Figure B.2. The CURRENT RANGE SELECTOR
provides five overlapping current ranges. The FINE
CURRENT ADJUSTMENT adjusts the current from
minimum to maximum within each range. Open circuit
voltage is also controlled by the FINE CURRENT
ADJUSTMENT, permitting control of the arc character-
istics.

A high open circuit voltage setting provides the soft
"buttering" arc with best resistance to pop-outs pre-
ferred for most welding. To get this characteristic, set
the CURRENT RANGE SELECTOR to the lowest set-
ting that still provides the current you need and set the
FINE CURRENT ADJUSTMENT near maximum. For
example: to obtain 175 amps and a soft arc, set the
CURRENT RANGE SELECTOR to the 190 -120 posi-
tion and then adjust the FINE CURRENT ADJUST-
MENT for 175 amps.

When a forceful "digging" arc is required, usually for
vertical and overhead welding, use a higher CURRENT
RANGE SELECTOR setting and lower open circuit
voltage. For example: to obtain 175 amps and a force-
ful arc, set the CURRENT RANGE SELECTOR to 240-
160 position and the FINE CURRENT ADJUSTMENT
setting to get 175 amps.

Some arc instability may be experienced with EXX10
electrodes when trying to operate with long arc tech-
niques at settings at the lower end of the open circuit
voltage range.

OPERATION

B-6

Classic III and IIID