Lincoln Electric SVM134-A service manual Control of Welding Current, Figure B.2 Current Controls

B-5 B-5

OPERATION

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CONTROL OF WELDING CURRENT

CAUTION

•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 to 120 position 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.

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FIGURE B.2 – CURRENT CONTROLS

	CURRENT RANGE	FINE CURRENT
	SELECTION	ADJUSTMENT	50
190-120		60
240-160	130-80	70	40
220	90	80	30
MAX.	MIN.
		90	20
		100	10	FINE CURRENT
IDLER	IGNITION PRESSURE	START	CHOKE	ADJUSTMENT
	OIL

CURRENT	REMOTE
	CONTROL
RANGE
SELECTOR

CLASSIC I