Lincoln Electric POWER MIG 255 SVM144-B - Manual (Page 20)

POWER MIG 255
OPERATION B-8 B-8
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5. Use only clean, rust-free electrode. The Lincoln
electrodes have proper surface lubrication.
6. Replace contact tip when the arc starts to become
unstable or the contact tip end is fused or
deformed.
7. Keep wire reel spindle brake tension to minimum
required to prevent excess reel over-travel which
may cause wire “loop-offs” from coil.
8. Use proper drive rolls and wire drive idle roll pres-
sure for wire size and type being used.
FAN CONTROL
The fan is designed to come on automatically when a
weld arc is established. The fan will stay on for a mini-
mum of 6 minutes after the weld arc is terminated. The
fan will also stay on when the machine’s welding and
feeding are disabled during thermostatic over temper-
ature protection. (See Welding Thermal Overload
Protection.)
INPUT LINE VOLTAGE
PROTECTION
High Line Voltage — If the line voltage exceeds 125%
of rated input voltage, the output will be reduced to the
lower level to protect voltage rating of the capacitor
bank.
Low Line Voltage — You may not be able to get max-
imum output from the machine if the line voltage is less
than rated input. The unit will continue to weld, but the
output may be less than what is set.
WIRE FEED OVERLOAD
PROTECTION
The POWER MIG has solid state overload protection
of the wire drive motor. If the motor becomes
overloaded, the protection circuitry turns off the wire
feed speed and gas solenoid. 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. There is no circuit breaker to reset as
the protection is done with reliable solid state
electronics.
WELDING THERMAL
OVERLOAD PROTECTION
The POWER MIG 255 has built-in protective ther-
mostats that respond to excessive temperature. They
open the wire feed and welder output circuits if the
machine exceeds the maximum safe operating tem-
perature because of a frequent overload, or high ambi-
ent temperature plus overload. The thermostats auto-
matically reset when the temperature reaches a safe
operating level and welding and feeding are allowed
again, when gun is retriggered.
OVERCURRENT PROTECTION
The machine will automatically reduce the output if the
load on the machine exceeds 300 to 320 amperes.
This protects the welding power SCR’s from excessive
short circuit currents and from exceeding their temper-
ature rating before the thermostats can react.
Welding Procedure Information
Note: See inside cover of machine for additional, commonly used welding procedure information.
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