Lincoln Electric IM843-C manual Welder Operation, Control of Welding Current

B-2 OPERATION B-2

Larger machines with a capacity of 350 amperes and higher, which are operated at low or no-load condi- tions for extended periods of time are especially sus- ceptible to the conditions described above. To accomplish successful engine break-in, most diesel- powered equipment needs only to be run at a reason- ably heavy load within the rating of the welder for some period of time during the engineʼs early life. However, if the welder is subjected to extensive light loading, occasional moderate to heavy loading of the engine may sometimes be necessary. Caution must be observed in correctly loading a diesel/generator unit.

1.Connect the welder output studs to a suitable resistive load bank. Note that any attempt to short the output studs by connecting the welding leads together, direct shorting of the output studs, or connecting the output leads to a length of steel will result in catastrophic damage to the generator and voids the warranty.

2.Set the welder controls for an output current and voltage within the welder rating and duty cycle. Note that any attempt to exceed the welder rating or duty cycle for any period of time will result in catastrophic damage to the generator and voids the warranty.

3.Periodically shut off the engine and check the crankcase oil level.

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.

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DUTY CYCLE

The NEMA output rating of the CLASSIC 300D KUB- OTA is 300 amperes at 32 arc volts on a 60% duty cycle (consult Specifications in this manual for alter- nate 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.

CLASSIC 300D KUBOTA