Lincoln Electric DC-400 specifications Machine & Circuit Protection Thermal Protection Light

A-7 INSTALLATION A-7

The individual case sides are removable for easy access for internal service or inspection.

The case rear, top section, is equipped with a remov- able access panel. This provides easy access to the input contactor, easy connection and reconnection of input leads, and easy access for service or inspection.

The total construction of the machine permits outdoor operation. The enclosure is designed with air intake louvers that keep dripping water from being drawn into the unit. The transformer, SCR bridge assembly, and choke are double-dipped in a special corrosion resis- tant coating.

A permanent lifting hook is located at the top of the machine and is positioned so that it acts as nearly as possible through the center of gravity.

ARC FORCE SELECTOR

(Effective only on CC for Stick and TIG Processes)

An ARC FORCE selector is provided similar to that used on the E500. This control allows the user to select the ideal arc force for the procedure and elec- trode being used.

ARC CONTROL

(Effective Only When Using CVI Mode)

The ARC CONTROL is a five-position switch that changes the pinch effect of the arc. This results in the control of spatter, fluidity, and bead shape. The ARC CONTROL is set to provide optimum welding depend- ing on the process being used, position, electrode, etc. The pinch effect is increased by turning the con- trol clockwise and may be adjusted while the machine is in operation.

MODE SWITCH

A MODE SWITCH selects between Constant Voltage (FCAW/GMAW), Constant Voltage (Submerged Arc), and Constant Current (Stick/TIG).

STICK WELDING

When the DC-400 is used for stick welding or air car- bon arc, the control leads and welding cables to any semiautomatic or automatic wire feeders must be dis- connected from the DC-400 for maximum safety (unless the Multiprocess switch option is installed).

PARALLELING

There are no provisions on the DC-400 to permit par- alleling.

DIODE OPTION

The DC-400 Diode option is required to utilize the cold start and cold electrode sensing features of the NA-3, NA-5 or NA-5R. When this option is not used with an NA-3, NA-5 or NA-5R, see the DC-400/NA-3, DC- 400/NA-5 or DC-400/NA-5R connection diagram for instructions on how to disable this circuit. If the circuit is not disabled, the wire cannot be inched down.

Machine & Circuit Protection (Thermal Protection Light)

The power source is thermostatically protected with proximity thermostats against overload or insufficient cooling. One thermostat is located on the nose of the center bottom primary coil and a second thermostat is attached to the lead connecting the secondaries. Both thermostats are connected in a series with the 2- 4 circuit. If the machine is overloaded, the primary thermostat will be open, the output will be zero, and the amber thermal protection light will be on. The fan will continue to run. The secondary thermostat will open either with an excessive overload or insufficient cooling. The output will be zero and the amber pro- tection light will be on. When the thermostats reset the protection light will be off.

The power source is also protected against overloads on the SCR bridge assembly through an electronic protection circuit. This circuit senses an overload on the power source and limits the output to 550 amps by phasing back the SCR’s.

Protection is provided to protect the circuitry from accidental grounds. If the customer accidentally “grounds” 75, 76, or 77 to the positive output lead, the DC-400 will be reduced to a low value, thus prevent- ing any damage to the machine. If the ground occurs between 75, 76, 77 and the negative output lead, one of the PC board “self-restoring” fuses will blow, pre- venting any machine damage.

DC-400