Welding Thermal Overload Protection; Overcurrent Protection - Lincoln Electric POWER MIG SVM170-A Service Manual

B-10
WELDING THERMAL OVERLOAD
PROTECTION
The POWER MIG 255C 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 temperature plus overload. The thermostats
automatically 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
temperature rating before the thermostats can react.
70
80 90
OPERATION
FIGURE B.5 — WELDING PROCEDURE INFORMATION
100 110 120
Note: See inside cover of machine for additional, commonly used welding procedure information.
POWER MIG 255C
English Wire
Length Part No.
12' (3.6 m) K533-7 .035 – .045"
15' (4.5 m) K533-3
B-10
Metric Wire
Size 1 Size
0.9 – 1.2 mm