Lincoln Electric Official Lincoln Welder Manual: Operation and Features of the DC-400

B-5 OPERATION B-5

GENERAL MACHINE DESCRIPTION

The DC-400 is an SCR controlled three phase DC power source. It is designed with a single range potentiometer control.

When using a DC-400 power source with wire feeders which do not have an electrical trigger interlock (or with wire feeders with the electrical trigger interlock in the OFF position), there will be a small spark if the electrode contacts the work or ground within several seconds after releasing the trigger.

When used with some wire feeders with the electrical trigger interlock in the ON position, the arc can restart if the electrode touches the work or ground during these several seconds.

WARNING

•Be sure to select OUTPUT TERMINALS “REMOTE ON/OFF” for operation with wire feed- ers that have leads numbered 2 and 4.

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RECOMMENDED PROCESSES & EQUIPMENT

The DC-400 model is designed for all open arc processes including Innershield® and all solid wire and gas procedures within the capacity of the machine, plus the capability of stick and TIG welding and air carbon arc gouging up to 5/16” (8mm) diameter. A mode switch selects CV (FCAW, GMAW), CV Submerged Arc, or CC (Stick/TIG). Stick welding per- formance is similar to that of the E500.

The DC-400 is designed to be used with the LN-7, LN-7 GMA, LN-8, LN-9, LN-9 GMA, LN-23P, LN-25, or LN-742 semiautomatic wire feeders, the NA-3, NA-5 and NA-5R automatics, and the LT-56 and LT-7 tractors, within the 400 ampere capacity of the machine. The DC-400 Diode Kit option is required to utilize the cold start and cold electrode sensing fea- tures of the NA-3, NA-5 and NA-5R.

OPERATIONAL FEATURES & CONTROLS

ARC CHARACTERISTICS

Through the unique combination of the transformer, three phase semiconverter rectifier, capacitor bank, arc control choke, and the solid state control system, outstanding arc characteristics are achieved on con- stant voltage.

In addition, an arc force control enables the DC-400 to stick weld as well as the E500.

OUTPUT CONTROL

The OUTPUT control, a small 2 watt potentiometer, is calibrated from 1 to 10. The OUTPUT control serves as a voltage control in the CV position and a current control in the CC position.

MACHINE OUTPUT CONTROL SWITCH “LOCAL” OR “REMOTE”

The machine output can be controlled by either the OUTPUT control on the machine control panel, the output control on the wire feed unit, or an optional “remote control” that is available. This switch selects the mode of control, either “LOCAL” or “REMOTE”.

OUTPUT TERMINALS “ON” OR OUTPUT TERMI- NALS “REMOTE”

This switch provides an alternative to the “2 to 4” jumpering function by energizing the machine’s output regardless of whether “2 or 4” is jumpered or not.

POLARITY SELECTION

Polarity selection is made by appropriately connecting the electrode and work welding cables to either the “+“ stud or to the “-” stud. Select “VOLTMETER” switch for “+” or “-” electrode, for the remote (#21) work sensing lead.

VOLTMETER SWITCH “+” ELECTRODE OR “-” ELECTRODE

This switch selects electrode polarity for the remote (#21) work sensing lead of automatic or semiautomat- ic equipment.

115 VOLT POWER SWITCH

The power input contactor operates from an auxiliary 115 volt transformer that is energized through the POWER toggle switch on the machine control panel.

“I “ is on and “0” is off.

PILOT LIGHT

A white light on the machine control panel indicates when the power source input contactor is closed. This means the main power transformer and all auxiliary and control transformers are energized.

THERMAL PROTECTION LIGHT

An amber light on the machine control panel indicates when either of the two protective thermostats have opened. Output power will be removed but input power will still be applied to the machine.

INPUT CONTACTOR

The power source is equipped with an input contactor.

DC-400