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