Lincoln Electric SP-255 manual 14OPERATION, Wire Feed Overload Protection, Overcurrent Protection

B-14OPERATION

LINE message will be displayed (see Section on Explanation of Prompting and Error Messages). The unit will continue to weld, but the output will be less than what is set.

WIRE FEED OVERLOAD

PROTECTION

The SP-255 has solid state overload protection of the wire drive motor. If the motor becomes overloaded, the protection circuitry turns off the arc voltage, wire feed speed and gas solenoid and then causes the alarm to beep 3 times. The screen displays a mes- sage for 2.5 seconds stating that the motor is being overloaded and the gun and wire drive should be checked. Check for proper size tip, liner, and drive rolls, for any obstructions or bends in the gun cable, and any other factors that would impede the wire feeding. To resume welding, simply pull the trigger.

WELDING THERMAL OVERLOAD PROTECTION

The SP-255 has built-in protective thermostats that respond to excessive temperature. they open the wire feed and welder output circuits if the machine exceeds the maximum safe operating temperature because of a frequent overload, or high ambient tem- perature plus overload. The thermostats automatically reset when the temperature reaches a safe operating level.

OVERCURRENT PROTECTION

The machine will automatically reduce the output if the load on the machine exceeds 260 to 280 amperes. This protects the welding power SCR’s from excessive short circuit currents and from exceeding their temperature rating before the thermostats can react. A CURRENT OVERLOAD message is dis- played when the overcurrent protection is active (see Section on Explanation of Prompting and Error Messages).

EXPLANATION OF PROMPTING AND ERROR MESSAGES

On Screen Error Message	Message Explanation
PROCESS MUST	Reminder that in Auto mode the process entered with the Process key must match
MATCH WIRE & GAS	the process installed in the machine.
ONLY SET UP FOR	Unit is only programmed for .035 (0.9 mm) diameter in stainless steel wire. Other
.035 STAINLESS	wire diameters can be accommodated by using the Manual mode.
ONLY ARGON USED	Unit is programmed to use only argon gas with aluminum electrodes. Other gases
WITH ALUMINUM	can be accommodated by using the Manual mode.
ONLY SET UP FOR	Unit is only programmed for .045 (1.1 mm) diameter in Outershield® electrode wire.
.045 OUTERSHIELD	Other wire diameters within the SP-255 rating can be accommodated by using the
	Manual mode.
NO GAS REQUIRED	Innershield® electrode wire does not require a shielding gas. In the Auto mode the
WITH INNERSHIELD	SP-255 automatically leaves the solenoid de-energized even when the trigger is
	closed.
MEMORY 1 NOW	Verifies that the setup was saved to memory number 1. The actual memory num-
CONTAINS SETUP	ber is determined by the memory number key that was pressed following Save.
MEMORY 2	An attempt was made to recall a setup from a memory that does not contain one.
IS EMPTY	The actual memory number is determined by the memory number key that was
	just pressed.
MEMORY 4 DOESN’T	An attempt was made to enter Toggle mode and the process of the Auto setup in
MATCH WIRE & GAS	memory 4 doesn’t match the process in the machine. Press memory 4 to find out
	what process is required. The memory number indicates which memory, 4 or 5,
	doesn’t match.
IDEALARC SP-255