Miller Electric PRO 300 User Manual

Standard features include: Stick, Lift-Arc™TIG, Flux Cored and MIG.

Other features include digital preset weld meters, output contactor
control, and automatic idle.

Processes

Stick (SMAW)
MIG (GMAW)
Flux Cored (FCAW)
DC TIG (GTAW)
Air Carbon Arc (CAC-A)

Rated: 3/16 in (4.8 mm) carbons,
Capable: 1/4 in (6.4 mm) carbons

Air Plasma Cutting and Gouging with

optional Spectrum models

Industrial Applications

Pipe Welding
Structural Steelwork
Fabrication
Maintenance
Repair

Quick
Specs

PRO 300

Engine-Driven Welder/

AC Generator

Issued May 2008 • Index No. ED/5.21

Auto Remote Sense (ARS) detects
if a remote control is plugged into
the 14-pin receptacle and eliminates
confusion of a remote/panel switch.

Simple-to-set controls require no
elaborate procedure — just select
process and weld!

Tailored Arc Control (DIG) allows
the arc characteristics to be
changed for specific applications
and electrodes. Smooth running
7018 or stiffer, more penetrating
6010 electrodes.

The Power of Blue®.

Welder/generator is warranted by Miller for 3 years, parts and labor.

Engine is warranted 3 years by engine manufacturer.

Miller Electric Mfg. Co.

An Illinois Tool Works Company
1635 West Spencer Street
Appleton, WI 54914 USA

Web Site

www.MillerWelds.com

International Headquarters

Phone: [phone]
USA FAX: [phone]
Canadian FAX: [phone]
International FAX: [phone]

Output Range DC Stick 40 – 410 A

DC TIG 20 – 410 A
FCAW/MIG 14 – 40 V

Generator Output Rated at 104˚ F (40˚ C)

12,000 Watts Peak
10,000 Watts Continuous

Quiet operation: Improves work
site communication.

CATERPILLAR C1.5,

21.7 HP @ 1800 RPM
industrial engine

Heavy-Duty Low-Speed
Industrial Engine Choices!

Deutz D2008 L04,

24.3 HP @ 1800 RPM
industrial engine

Designed to operate over 10,000
hours before the first basic
overhaul. Backed by worldwide
support and service.

Thermal overload protection

prevents machine damage if the
duty cycle is exceeded or airflow
is blocked.

Optional Stainless Steel
Appearance Package provides

additional exterior protection to
withstand corrosive environments.

Improved!

Superior Arc

Performance!

Accu-Rated

™

– Not Inflated

Generator Power

The Professional Welder’s
Choice — designed with the

professional in mind, the
PRO 300 is the best for ease of
use, reliability and fuel economy.

Superior arc performance

• Four preset DIG settings (Stick)

• Hot Start

™

(Stick)

• Lift-Arc™TIG with Auto-Stop

™

and Crater-out

• MIG/FCAW arc performance

Meter maintenance displays.

• Hour meter function

• Oil change interval

• High coolant temperature and
low oil pressure shutdowns

• Low fuel shutdown — engine
shuts downs before system
runs out of fuel, making
restarts easy.

The Vault — ultimate control
board reliability. See page 4.

Performance Data

2

Specifications (Subject to change without notice.)

Engine Specifications (Engines warranted separately by the engine manufacturer.)

Engine Brand

CATERPILLAR
C1.5

Deutz D2008
L04

Features

EPA Tier III indirect-injected liquid-cooled
engine. Right side service access with
intervals of 250 hrs for oil and filters.

EPA Tier IVi indirect-injected liquid-cooled
engine. Right side service access with
intervals of 250 hrs for oil and filters.

HP

21.7

24.3

Type

3-cylinder, industrial
liquid-cooled, diesel

4-cylinder, industrial
liquid-cooled, diesel

Engine
Speeds

1850 RPM weld
(1500 RPM idle)

1800 RPM weld
(1500 RPM idle)

Fuel
Capacity

11.5 gal
(43.5 L)

Oil
Capacity

6 qt
(5.7 L)

Coolant
Capacity

6 qt
(5.7 L)

Automatic Engine
Shutdown

Low Oil Pressure,
High Coolant
Temperature,
Low Fuel Level

SIMULTANEOUS WELDING AND POWER

225
175
125
75
25

Weld
Amperes

Total Power
Available (Watts)

120 V 240 V

3000
5000
5900
7300
10,000

25

41.6

49.2

60.8

83.5

12.5

20.8

24.6

30.4

41.7

STICK MODE V/A CURVE – MAX DIG

DC VOLTS

DC AMPERES

0 100 200 300 400 500

600

100

90
80
70

60
50
40
30
20
10

0

MIN

MAX

300

MIG MODE V/A CURVE

0 100 200 300 400 500 600

100

80
60
40
20

0

DC VOLTS

DC AMPERES

MIN

MAX

FUEL CONSUMPTION CURVE

IDLE

DC WELD AMPERES

AT 100% DUTY CYCLE

U.S. GAL/HR.

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

0

50 100 150 200 250 300 350 400

GENERATOR POWER CURVE

0 40 80 120 160

020406080

AC AMPERES IN 120 V MODE

AC AMPERES IN 240 V MODE

300

250

200

150

100

50

0

150

125

100

75

50

25

0

AC VOLTS

DC TIG MODE V/A CURVE

DC VOLTS

DC AMPERES

0 100 200 300 400 500

100

90
80
70

60
50
40
30
20
10

0

MIN

MAX

300

Weld
Mode

CC/DC

CV/DC

Weld Output
Range

20 – 410 A

14 – 40 V

Weld Output Rated
at 104˚ F (40˚ C)

400 A, 20 VDC,
30% Duty Cycle
300 A, 32 VDC,
60% Duty Cycle

Max. Open­Circuit Voltage

65

Generator Power Output
Rated at 104˚ F (40˚ C)

12,000 Watts Peak
10,000 Watts Continuous
Single-phase, 120/240 VAC,
83/42 A 60 Hz

Dimensions

H: 32 in
(813 mm)
W: 26-1/4 in
(667 mm)
D: 56 in
(1422 mm)

Net Weight
(without fuel)*

CAT:

Net: 1128 lb (512 kg)
Ship: 1150 lb (522 kg)

Deutz:

Net: 1208 lb (548 kg)
Ship: 1230 lb (558 kg)

Sound Levels at Rated
Output, 7 m (23 ft)

CAT:

71 dB (96 Lwa)

Deutz:

73 dB (98 Lwa)

CSA approved. Meets NEMA and IEC output ratings. *Additional 82 lb (37 kg) when fuel tank is full.

3

Function Guide

1. Self-calibrating digital weld meters with
meter maintenance displays.

2. Four Preset DIG Settings offer the best

arc characteristics for different electrodes
and joint designs. The amount of DIG
determines how much amperage (heat)
varies with Stick arc length. The combined
Process switch along with preset DIG
settings make the PRO 300 easy to set
without the complication of multiple switches.

3. Hot Start

™

provides positive Stick electrode
starts making it easy to start all types of
electrodes and it also works great for bead
tie-ins.

4. Great MIG/FCAW Performance and Arc
Starts make the PRO 300’s arc best in its

class. Easy to run all wires from .023 in
solid wires to large diameter 5/64 in
flux cored wires.

5. Lift-Arc

™

TIG with Auto-Stop™and

Crater-out (patents pending)

6. Standard 14-Pin Receptacle for simple

connection of remote controls and wire
feeders. It features Auto Remote Sense

™

which automatically switches from Panel to
Remote Amperage/Voltage (A/V) control
with remote connected. Eliminates
confusion of the Panel/Remote A/V switch.

7. Weatherproof Lexan

®

Nameplate is super

durable and resists cracking and fading.
Color coding is for ease of operation.

8. Fuel Gauge displays engine hours and oil
change interval information.

Low Fuel Shutdown shuts engine off prior
to running out of fuel to prevent loss of fuel
in the system, and make restarts easy.
Display will read noFUEL. Turn the machine
off, add fuel, and restart.

9. Glow Plugs assist in cold weather starting.

10. Engine Control Switch is used to start the

engine and then select between Auto Idle
and High Speed Lock.

11. Amperage/Voltage Adjust Control

12. 120 VAC and 240 VAC Receptacles with
Circuit Breakers (optional 120 VAC GFCI

receptacles available).

Note: For matching plug, order #119 172.

13. Weld Output Terminals

• Eliminates need for
a remote control

• Maintains shielding
gas coverage

• Eliminates tungsten
and workpiece
contamination

• Eliminates
unwanted arc
strikes outside the
weld area

• Reduces or eliminates sticking

• Reduces or eliminates electrode/
work contamination

• Low open-circuit voltage
(approximately 10 volts)

• Maintains shielding
gas coverage

• Eliminates tungsten
and workpiece
contamination

• Crater-out time
allows for addition
of filler

• Eliminates
unwanted arc
strikes outside
the weld area

1

8

2
3

4

9

10

11

5

12

6

7

13

Arc

™

Lift at any angleTouch or scratch

Shielding

gas

ARC START with Lift-Arc

Shielding

gas

Workpiece

ARC END with Auto-Stop

While welding

Lift up

gas

until arc

ends

Shielding

Arc

Workpiece

ARC END with Crater-out

While welding

Shielding

Arc

Workpiece

To start Crater-out, press

momentary contact switch

gas

™

For Auto-Stop, lift up to terminate arc

Arc ends

without

flare

Welding

current

ramps

down

maintain gas

Maintain
shielding

coverage

Move back

down to

coverage

gas