POWER SOURCE OPERATION
Duty Cycle and Time Period
The DC-400 is rated at the following duty cycles:
* Based upon 10 minute time period (ie. for 60% duty cycle,
it is 6 minutes on and 4 minutes off).
Overloading the DC-400 may result in opening of an
internal protective thermostat as indicated by the amber
thermal protection light turning on.
STARTING THE MACHINE
The POWER toggle switch at the extreme right side of the
control panel in the “I“ position energises and closes the
three phase input contactor from a 115 volt auxiliary
transformer.
This in turn energises the main power
transformer.
The machine is de-energised when the POWER switch is
in the “0” position.
The white light below the POWER switch indicates when
the input contactor is energised.
OUTPUT CONTROL DIAL
The OUTPUT control to the right of the centre of the control
panel is a continuous control of the machine output. The
control may be rotated from minimum to maximum while
under load to adjust the machine output.
The machine is equipped with line voltage compensation
as a standard feature. This will hold the output constant
except at maximum output of the machine, through a
fluctuation of ±10% input line voltage.
OUTPUT CONTROL “LOCAL-REMOTE” SWITCH
The OUTPUT CONTROL toggle switch on the control
panel labelled “LOCAL-REMOTE” gives the operator the
option of controlling the output at the machine control panel
or at a remote station. For remote control, the toggle switch
is set in the “REMOTE” position and controlled at the wire
feed unit control, or by connecting a K775 control to
terminals 75, 76, and 77 on the terminal strip at the front of
the machine, or by connecting a K857 control to the 14-pin
connector on the front of the machine. For control at the
machine control panel, the toggle switch is set in the
“LOCAL” position.
(Exception: When used with an LN-9, LN-9 GMA or NA-5
wire feeder, the OUTPUT CONTROL switch must be in the
“REMOTE” position or automatic shutdown of the LN-9 or
NA-5 may occur.)
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
Select “+” for positive electrode or “-” for negative electrode
polarity for the remote (#21) work sensing lead of automatic
or semiautomatic equipment.
THERMAL PROTECTION LIGHT
The amber thermal protection light will be lit if either of the
two protective thermostats have opened. The output power
will be disabled but input power will still be applied to the
welder. (Refer to Machine and Circuit Protection section).
MODE SWITCH
The large MODE SWITCH on the left side of the machine,
labelled “Constant Voltage (Submerged Arc), Constant
Voltage (FCAW/GMAW) and Constant Current (Stick/TIG)”,
is used to select the proper welder characteristics for the
process being used.
The CV (FCAW/GMAW) Mode permits the DC-400 to
produce essentially a flat output characteristic that can be
varied from approx. 12 to 42 volts.
In this position, the dynamic characteristics of the machine
under welding conditions provide optimum welding
characteristics for Innershield® welding, other open arc
processes including short arc MIG welding, and air carbon
arc. Most submerged arc welding can also be done in this
mode.
The CV (Submerged Arc) Mode also produces an
essentially flat output characteristic that can be varied from
approximately 12 to 42 volts. The dynamic characteristics
of the CV Submerged Arc Mode make possible improved
submerged arc welding over that possible using the
Constant Voltage Innershield Mode. The improvement is
most noticeable on high deposition, slow travel speed
welds.
There are no means provided to switch between any of the
modes remotely. Do not change the position of the MODE
SWITCH if output voltage or current is present as this may
damage the switch.
The CC Mode permits the DC-400 to produce a constant
current output characteristic through the range of 60-500
amps with an open circuit voltage of approximately 57 volts.
Stick welding and TIG are done with this position of the
Mode Switch.
Page 18
DC-400
IMA 474
Duty Cycle *
Amps
Volts
100%
400
36
60%
450
38
50%
500
40
ELECTRIC SHOCK can kill
•
Have an electrician install and service this equipment..
•
Turn the input power off at the fuse box before working
on equipment.
•
Do not touch electrically hot parts.
WARNING
ARC WELDING SUPPLIES - 07 847 7870
