Lincoln Electric SA-250 manual Welder Operation, Control of Welding Current, Idler Operation

B-3 OPERATION B-3

WELDER OPERATION

WARNING

ELECTRIC SHOCK can kill.

•Do not touch electrically live parts or electrode with skin or wet clothing.

•Insulate yourself from work and ground.

FUMES & GASES can be dangerous.

• Keep your head out of the fumes.

•Use ventilation or exhaust to remove fumes from breathing zone.

WELDING SPARKS can cause fire or

explosion.

• Keep flammable material away.

ARC RAYS can burn.

• Wear eye, ear, and body protection.

DUTY CYCLE

The NEMA output rating of the SA-250 is 300 amperes at 32 arc volts on a 60% duty cycle (consult Specifications in this manual for alternate ratings). Duty cycle is based on a ten minute period; thus, the welder can be loaded at rated output for six minutes out of every ten minute period.

CONTROL OF WELDING CURRENT

CAUTION

DO NOT TURN THE “CURRENT RANGE SELEC- TOR” WHILE WELDING because the current may arc between the contacts and damage the switch.

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The “Current Range Selector” provides five overlap- ping 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 characteristics.

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 setting 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 position and then adjust the “Fine Current Adjustment” 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 volt- age. For example: to obtain 175 amps and a forceful arc, set the “Current Range Selector” to the 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.

CAUTION

DO NOT attempt to set the “Current Range Selector” between the five points designated on the nameplate.

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These switches have a spring loaded cam which almost eliminates the possibility of setting this switch between the designated points.

IDLER OPERATION

Start the engine with the “Idler” switch in the “High” position. Allow it to run at high idle speed for several minutes to warm the engine. See Specifications for operating speeds.

The idler is controlled by the “Idler” toggle switch on the welder control panel. The switch has two posi- tions as follows:

1. In the “High” position, the idler solenoid acti- vates, and the engine goes to high idle speed. The speed is controlled by the governor.

2.In the “Auto” / position, the idler oper- ates as follows:

•When welding or drawing power for lights or tools (approximately 100-150 watts minimum) from the receptacles, the idler solenoid activates and the engine operates at high idle speed.

•When welding ceases or the power load is turned off, a preset time delay of about 15 seconds starts. This time delay cannot be adjusted.

•If the welding or power load is not re-started before the end of the time delay, the idler solenoid deacti- vates and reduces the engine to low idle speed.

SA-250