3. Primary Connections; 4. Secondary Welding Connections - Miller Two Fifty Twin Owner's Manual

~ldi
ng p owe r
~e
should be loca ted
so
that
the front and
rear
panels with the air
vents are
clear
of
any
obstruction.
Cooling air is drawn
in through the
front upper air
vent
and
expelled
Out
of the
rear
panel
air
vent.
The location should be such that
a
minimum
amount
of dust
and dirt will be drawn into the air
stream.
Preventive main
tenance
consists of
removing the wrapper from the welding
power source
and blowing
Out
the dust accumulation inside
the unit. For this
reason
it is desirable
to
locate the unit
so
that the wrapper
can
be removed without
any
difficulty.
This
ac/dc
arc
welding
power source
is
a
single phase unit and
must
be connected
to
a
single phase power line. Consult the
local public electric utility if there is any
question about the
system used locally
or
the proper connections necessary
to
connect
single phase power service
to
the welding
power
source.
NOTE
It is recommended that the
primary leads be of
the
heavy rubber covered type
or run
in solid
or
flexible
conduit. Select the proper size
primary fuse and cable
from Table 3-1.
Table 3-1. Primary Wire and Fuse Size
PRIMARY WI RE SIZE IAWGI FUSE SIZE
IN AMPERES
MODEL 200V 230V 460V 57Ev 200V 230V 460V 57EV
WIhoot P,F.C. No. 2
No.2 No.6 No.8 150 150 70 60
With P.F.C. No. 3
No.4
No.8
No. 10 125 100 50 40
18) (8) (8) (8)
Numbers in (I indicate ground
wire size.
Insert the
two
primary
leads
plus
one
ground lead
through
the access hole provided
on
the lower
left
portion
of the
rear
panel. See Figure 3-2 for hole location. This 1-3/4 inch dia
meter
hole will accept standard conduit fittings.
The
two
primary
leads
are to
be connected
to
terminals Li
and L2
on
the primary terminal board
(TEl),
which
is
located behind the
primary
access
door
on
the
rear
panel.
The ground lead
must
be connected
to
the stud
on
the pri
mary
terminal board labeled GAD. The remaining
end of the
ground lead should be connected
to
a
suitable
ground
such
as: a
water
pipe, ground rod,
etc.
Use whatever grounding
means
is acceptable
to
the local
electrical
inspection
authority.
.
The stud labeled CR0 is
connected~
welding
power source
chassis and is for
grounding
purposes
only. Do
not connect
a
wire from the terminal labeled
GAD
to
either
one
of the
single phase
line terminals
as
this will result in
an
electrically hot
welding
power
source
chassis.
The standard
welding
power source
is
designed
to
operate on
either
200, 230
or
460 volts, 60 Hertz
primary electrical
power. This machine
was
shipped
from the
factory with the
jumper links
arranged for the
highest voltage
the machine has
been
designed
to operate
on.
To
setup
the
welding
power
source
for the
voltage
to
be
used, position the
jumper links,
located
on
the primary
terminal board,
as
shown in Figure
3-3.
200
(208) VOLTS 230 VOLTS
460 VOLTS
~oo~ o~o oo~~
0
0
0
00 0. 00 0
GA.
LI 17
Gfl
LI 12
60
II
17
A-OlO 586
Figure 3-3.
Primary Voltage Jumper Link
Arrangement
~ver
on
ly
a ne umper
link
con
nection is
nec
essary
to
obtain the proper
input voltage connections,
such
as
460 volts,
connect
both
jumper
links
across
the
same
two
terminals. This will prevent losing the
second jumper link.
It is recommended that the welding
cables be
kept
as
short
as
possible, placed close together and be of adequate
current
carrying capacity.
The resistance of the
welding
cables and
connections
cause a
voltage drop which is added
to
the volt
age of the
arc.
Excessive cable resistance may result in
over
loading
as
well
as
reducing the maximum
current
output of
which the welding
power source
is
capable.
The proper operation
of
any arc
welding
power
source
is
to
a
great extent
dependent
on
the
use
of welding cables and
connections that
are
in good
condition and of adequate size.
An insulated holder
must
be used
to
ensure
the
operators
safety.
Id in gw~h
ac,
if the
cables
a re
coiled
up
they
will
generate
a
magnetic field that will seri
ously affect the operation of the welding
power
source.
Always lay
the welding cables
out.
PRIMARY CABLE
INPUT HOLE
PRIMARY VOLTAGE
JUMPER LINKS
3-3/8
LINE
DISCONNECT
SWITCH
GROUND
CONNECTION
Figure 3-2.
Primary Connections
AC-901 973.3
Figure 3-1, Dimensional Drawing
3-3.
PRIMARY CONNECTIONS
3-4. SECONDARY WELDING CONNECTIONS
Page 6