MIL-W-80027D
The sheet metal enclosure shall be dripproof, so
Enclosure.
3.4.1
designed and constructed that liquid or solid particles falling on the
enclosure from above, at angles Up to 15 degrees from the vertical, shall
not interfere with the satisfactory operation of the equipment. Surfaces of
all parts of the enclosure shall be free from sand, dirt, fins, sprues,
External surfaces
scale, flux, or other harmful or extraneous materials.
shall be smooth, and all protruding edges shall be rounded or beveled and
Inlet and outlet electrical
all other edges shall be free of burrs.
The output welding
connections shall be clearly and permanently marked.
terminals shall be of the stud and hex nut type, not less than 13 mm (1/2
inch) in diameter, or receptacles of equivalent capacity with a pair of
All intake
matching plugs suitable for attachments to the welding leads.
and exhaust openings shall be screened or shall be small enough to prevent
entrance of trash or rodents.
Transformer.
The transformer shall be of the laminated core or
3.4.2
shell type.
Insulation system of primary and secondary transformer coils
shall be B, F, or H in accordance with the definition of NEMA EW-1.
Transformer coil windings shall be
3.4.2.1 Overtemperature protection.
protected by a suitable device or devices, to de-energize the machine and
A combination
prevent damage to the windings by precluding overheating.
overtemperature and overload device may be used in lieu of separate controls
for protection against excess overtemperatures and overloads.
3.4.3 Rectifier. The rectifier shall be of the silicon diode, full wave
type. The assembly shall be of a type which has had a satisfactory history
Temperature rise of the silicon
of field service in general arc welding.
diodes shall not exceed 100 degrees C
when operated at rated output
and duty cycle.
3.4.4 Controls.
3.4.4.1 Control panel. The control panel shall be located on the machine
enclosure and shall provide central location for all switches, controls, and
electrical outlets.
The current control shall permit adjustment of the
current from minimum to maximum in increments small enough to satisfy any
required setting within the range of the machine.
A switch shall be pro-
vided to select AC welding or straight and reverse DC welding.
All panel
mounted components shall be clearly marked as to their function.
The con-
trol panel shall be recessed.
Operation of adjustment controls shall be
free from binding, and controls shall be of such materials and design that a
fixed setting will remain after several hours of exposure to adverse atmo-
spheric conditions. For type I machines, provisions shall be made for grad-
ual application of weld current at the start of the welding operation to
prevent blasting.
A switch shall be provided to bypass this circuit when
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