Thermal Arc ARCMASTER 300 AC/DC User manual

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INVERTER
Operating Manual
ARCMASTER®
Version No: 1Issue Date: February 22, 2006 Manual No.: 0-4863
Operating Features:
INVERTER ARC WELDER
300 AC/DC
Art # A-07238

WE APPRECIATE YOUR BUSINESS!
Congratulations on your new Thermal Arc product. We are proud
to have you as our customer and will strive to provide you with
the best service and reliability in the industry. This product is backed
by our extensive warranty and world-wide service network. To
locate your nearest distributor or service agency call
1-800-752-7621, or visit us on the web at www.Thermalarc.com.
This Operating Manual has been designed to instruct you on the
correct use and operation of your Thermal Arc product. Your
satisfaction with this product and its safe operation is our ultimate
concern. Therefore please take the time to read the entire manual,
especially the Safety Precautions. They will help you to avoid
potential hazards that may exist when working with this product.
YOU ARE IN GOOD COMPANY!
The Brand of Choice for Contractors and Fabricators Worldwide.
Thermal Arc is a Global Brand of Arc Welding Products for
Thermadyne Industries Inc. We manufacture and supply to major
welding industry sectors worldwide including; Manufacturing,
Construction, Mining, Automotive, Aerospace, Engineering, Rural
and DIY/Hobbyist.
We distinguish ourselves from our competition through market-
leading, dependable products that have stood the test of time. We
pride ourselves on technical innovation, competitive prices,
excellent delivery, superior customer service and technical support,
together with excellence in sales and marketing expertise.
Above all, we are committed to develop technologically advanced
products to achieve a safer working environment within the welding
industry.

WARNINGS
Read and understand this entire Manual and your employer’s safety practices before installing,
operating, or servicing the equipment.
While the information contained in this Manual represents the Manufacturer's best judgement,
the Manufacturer assumes no liability for its use.
ArcMaster 300 AC/DC Inverter Arc Welder
Instruction Manual Number 0-4863 for:
Part Number 10-3074
Published by:
Thermadyne Corporation
82 Benning Street
West Lebanon, New Hampshire, USA 03784
[phone]
www.thermalarc.com
Copyright 2006 by
Thermadyne Corporation
All rights reserved.
Reproduction of this work, in whole or in part, without written permission of the pub-
lisher is prohibited.
The publisher does not assume and hereby disclaims any liability to any party for any
loss or damage caused by any error or omission in this Manual, whether such error
results from negligence, accident, or any other cause.
Publication Date: February 22, 2006
Record the following information for Warranty purposes:
Where Purchased: ___________________________________
Purchase Date: ___________________________________
Equipment Serial #: ___________________________________
i

TABLE OF CONTENTS
SECTION 1:
SAFETY INSTRUCTIONS AND WARNINGS ....................................................... 1-1
1.01 Arc Welding Hazards ...................................................................................... 1-1
1.02 Principal Safety Standards ............................................................................. 1-5
1.03 Precautions de Securite en Soudage à L’Arc .................................................. 1-6
1.04 Dangers Relatifs au Soudage à L’Arc .............................................................. 1-6
1.05 Principales Normes de Securite ................................................................... 1-10
1.06 Limited Warranty.......................................................................................... 1-11
SECTION 2:
INTRODUCTION ...................................................................................... 2-1
2.01 How To Use This Manual ................................................................................ 2-1
2.02 Equipment Identification................................................................................. 2-1
2.03 Receipt Of Equipment ..................................................................................... 2-1
2.04 Symbol Chart ................................................................................................. 2-2
2.05 Description ..................................................................................................... 2-3
2.06 Functional Block Diagrams ............................................................................. 2-4
2.07 Transporting Methods .................................................................................... 2-4
SECTION 3:
INSTALLATION ....................................................................................... 3-1
3.01 Environment ................................................................................................... 3-1
3.02 Location ......................................................................................................... 3-1
3.03 Electrical Input Connections ........................................................................... 3-1
3.04 Electrical Input Requirements ........................................................................ 3-2
3.05 Input Power.................................................................................................... 3-3
3.06 High Frequency Introduction .......................................................................... 3-3
3.07 High Frequency Interference .......................................................................... 3-4
3.08 Duty Cycle ...................................................................................................... 3-4
3.09 Specifications ................................................................................................. 3-5
SECTION 4:
OPERATOR CONTROLS ............................................................................. 4-1
4.01 ArcMaster 300 ACDC Controls ....................................................................... 4-1
4.02 Weld Process Selection for ArcMaster 300 ACDC .......................................... 4-3
4.03 Weld Parameter Descriptions for ArcMaster 300 ACDC ................................. 4-4
4.04 Weld Parameters for ArcMaster 300 ACDC .................................................... 4-6
4.05 Power Source Features................................................................................... 4-7
SECTION 5:
SET-UP FOR SMAW (STICK) AND GTAW (TIG) .................................................. 5-1

TABLE OF CONTENTS (continued)TABLE OF CONTENTS
SECTION 6:
SEQUENCE OF OPERATION ........................................................................ 6-1
6.01 Stick Welding ................................................................................................. 6-3
6.02 AC or DC HF TIG Welding ............................................................................... 6-3
6.03 Slope Mode Sequence .................................................................................... 6-4
6.04 Slope Mode with repeat sequence .................................................................. 6-4
6.05 Pulse Controls ................................................................................................ 6-5
SECTION 7:
BASIC TIG WELDING GUIDE ....................................................................... 7-1
7.01 Explanation of “Fluttery Arc” when AC TIG Welding on Aluminum ................. 7-1
7.02 Electrode Polarity ........................................................................................... 7-2
7.03 Tungsten Electrode Current Ranges ............................................................... 7-2
7.04 Tungsten Electrode Types ............................................................................... 7-2
7.05 Guide for Selecting Filler Wire Diameter ......................................................... 7-3
7.06 Shielding Gas Selection .................................................................................. 7-3
7.07 TIG Welding Parameters for Low Carbon & Low Alloy Steel Pipe .................. 7-3
7.08 Welding Parameters for Aluminum ................................................................ 7-4
7.09 Welding Parameters for Steel ......................................................................... 7-4
SECTION 8:
BASIC ARC WELDING GUIDE ..................................................................... 8-1
8.01 Electrode Polarity ........................................................................................... 8-1
8.02 Effects of Stick Welding Various Materials ..................................................... 8-1
SECTION 9:
ROUTINE MAINTENANCE .......................................................................... 9-1
SECTION 10:
BASIC TROUBLESHOOTING ...................................................................... 10-1
10.01 ........................................................................................TIG Welding Problems
10.02 ......................................................................................Stick Welding Problems
10.03 ..................................................................................... Power Source Problems
SECTION 11:
VOLTAGE REDUCTION DEVICE (VRD) ........................................................... 11-1
11.01 ............................................................................................... VRD Specification
11.02 ............................................................................................... VRD Maintenance
11.03 ........................................................................................ Switching VRD On/Off
SECTION 12:
POWER SOURCE ERROR CODES................................................................. 12-1

TABLE OF CONTENTS
SECTION 13:
PARTS LIST ......................................................................................... 13-1
13.01 ..................................................................................... Equipment Identification
13.02 ................................................................................. How To Use This Parts List
LIMITED WARRANTY
WARRANTY SCHEDULE
GLOBAL CUSTOMER SERVICE CONTACT INFORMATION .......................... Inside Rear Cover

ARCMASTER 300 ACDC
1-1
February 22, 2006
1.01 Arc Welding Hazards
WARNING
ELECTRIC SHOCK can kill.
Touching live electrical parts can cause fatal
shocks or severe burns. The electrode and
work circuit is electrically live whenever the
output is on. The input power circuit and
machine internal circuits are also live when
power is on. In semiautomatic or automatic
wire welding, the wire, wire reel, drive roll
housing, and all metal parts touching the
welding wire are electrically live. Incorrectly
installed or improperly grounded equipment
is a hazard.
1. Do not touch live electrical parts.
2. Wear dry, hole-free insulating gloves and body
protection.
3. Insulate yourself from work and ground using dry
insulating mats or covers.
4. Disconnect input power or stop engine before
installing or servicing this equipment. Lock input
power disconnect switch open, or remove line fuses
so power cannot be turned on accidentally.
5. Properly install and ground this equipment according
to its Owner’s Manual and national, state, and local
codes.
6. Turn off all equipment when not in use. Disconnect
power to equipment if it will be left unattended or out
of service.
7. Use fully insulated electrode holders. Never dip holder
in water to cool it or lay it down on the ground or the
work surface. Do not touch holders connected to two
welding machines at the same time or touch other
people with the holder or electrode.
8. Do not use worn, damaged, undersized, or poorly
spliced cables.
9. Do not wrap cables around your body.
10.Ground the workpiece to a good electrical (earth)
ground.
SECTION 1:
SAFETY INSTRUCTIONS AND WARNINGS
WARNING
PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH. KEEP CHILDREN AWAY.
PACEMAKER WEARERS KEEP AWAY UNTIL CONSULTING YOUR DOCTOR. DO NOT LOSE THESE INSTRUCTIONS.
READ OPERATING/INSTRUCTION MANUAL BEFORE INSTALLING, OPERATING OR SERVICING THIS EQUIPMENT.
Welding products and welding processes can cause serious injury or death, or damage to other equipment or property,
if the operator does not strictly observe all safety rules and take precautionary actions.
Safe practices have developed from past experience in the use of welding and cutting. These practices must be
learned through study and training before using this equipment. Some of these practices apply to equipment
connected to power lines; other practices apply to engine driven equipment. Anyone not having extensive
training in welding and cutting practices should not attempt to weld.
Safe practices are outlined in the American National Standard Z49.1 entitled: SAFETY IN WELDING AND CUTTING.
This publication and other guides to what you should learn before operating this equipment are listed at the end of
these safety precautions. HAVE ALL INSTALLATION, OPERATION, MAINTENANCE, AND REPAIR WORK PERFORMED
ONLY BY QUALIFIED PEOPLE.

ARCMASTER 300 ACDC
1-2 February 22, 2006
11.Do not touch electrode while in contact with the work
(ground) circuit.
12.Use only well-maintained equipment. Repair or replace
damaged parts at once.
13.In confined spaces or damp locations, do not use a
welder with AC output unless it is equipped with a
voltage reducer. Use equipment with DC output.
14.Wear a safety harness to prevent falling if working
above floor level.
15.Keep all panels and covers securely in place.
WARNING
ARC RAYS can burn eyes and skin; NOISE can
damage hearing.
Arc rays from the welding process produce
intense heat and strong ultraviolet rays that
can burn eyes and skin. Noise from some
processes can damage hearing.
1. Wear a welding helmet fitted with a proper shade of
filter (see ANSI Z49.1 listed in Safety Standards) to
protect your face and eyes when welding or watching.
2. Wear approved safety glasses. Side shields
recommended.
3. Use protective screens or barriers to protect others
from flash and glare; warn others not to watch the
arc.
4. Wear protective clothing made from durable, flame-
resistant material (wool and leather) and foot
protection.
5. Use approved ear plugs or ear muffs if noise level is
high.
WARNING
FUMES AND GASES can be hazardous to your
health.
Welding produces fumes and gases. Breathing
these fumes and gases can be hazardous to
your health.
1. Keep your head out of the fumes. Do not breath the
fumes.
2. If inside, ventilate the area and/or use exhaust at the
arc to remove welding fumes and gases.
3. If ventilation is poor, use an approved air-supplied
respirator.
4. Read the Material Safety Data Sheets (MSDSs) and
the manufacturer’s instruction for metals,
consumables, coatings, and cleaners.
5. Work in a confined space only if it is well ventilated,
or while wearing an air-supplied respirator. Shielding
gases used for welding can displace air causing injury
or death. Be sure the breathing air is safe.
Welding or cutting Electrode Size Filter Welding or cutting Electrode Size Filter
Torch soldering 2 Gas metal-arc
Torch brazing 3 or 4 Non-ferrous base metal All 11
Oxygen Cutting Ferrous base metal All 12
Light Under 1 in., 25 mm 3 or4 Gas tungsten arc welding All 12
Medium 1 to 6 in.,25-150 mm 4 or5 (TIG) All 12
Heavy Over 6 in.,150 mm 5 or 6 Atomic hydrogen welding All 12
Gas welding Carbon arc welding All 12
Light Under1/8 in.,3 mm 4 or 5 Plasma arc welding
Medium 1/8 to 1/2 in.,3-12 mm 5 or 6 Carbonarc air gouging
Heavy Over1/2 in.,12 mm 6 or 8 Light 12
Shielded metal-arc Under5/32 in.,4 mm 10 Heavy 14
5/32 to 1/4 in., 12 Plasma arc cutting
Over 1/4 in.,6.4 mm 14 Light Under 300 Amp 9
Medium 300 to 400 Amp 12
Heavy Over400 Amp 14
Eye protectionfilter shade selector for welding or cutting
(goggles or helmet), from AWS A6.2-73.

ARCMASTER 300 ACDC
1-3
February 22, 2006
6. Do not weld in locations near degreasing, cleaning, or
spraying operations. The heat and rays of the arc can
react with vapors to form highly toxic and irritating
gases.
7. Do not weld on coated metals, such as galvanized,
lead, or cadmium plated steel, unless the coating is
removed from the weld area, the area is well ventilated,
and if necessary, while wearing an air-supplied
respirator. The coatings and any metals containing
these elements can give off toxic fumes if welded.
WARNING
WELDING can cause fire or explosion.
Sparks and spatter fly off from the welding
arc. The flying sparks and hot metal, weld
spatter, hot workpiece, and hot equipment can
cause fires and burns. Accidental contact of
electrode or welding wire to metal objects can
cause sparks, overheating, or fire.
1. Protect yourself and others from flying sparks and
hot metal.
2. Do not weld where flying sparks can strike flammable
material.
3. Remove all flammables within 35 ft (10.7 m) of the
welding arc. If this is not possible, tightly cover them
with approved covers.
4. Be alert that welding sparks and hot materials from
welding can easily go through small cracks and
openings to adjacent areas.
5. Watch for fire, and keep a fire extinguisher nearby.
6. Be aware that welding on a ceiling, floor, bulkhead, or
partition can cause fire on the hidden side.
7. Do not weld on closed containers such as tanks or
drums.
8. Connect work cable to the work as close to the welding
area as practical to prevent welding current from
traveling long, possibly unknown paths and causing
electric shock and fire hazards.
9. Do not use welder to thaw frozen pipes.
10.Remove stick electrode from holder or cut off welding
wire at contact tip when not in use.
WARNING
FLYING SPARKS AND HOT METAL can cause
injury.
Chipping and grinding cause flying metal. As
welds cool, they can throw off slag.
1. Wear approved face shield or safety goggles. Side
shields recommended.
2. Wear proper body protection to protect skin.
WARNING
CYLINDERS can explode if damaged.
Shielding gas cylinders contain gas under high
pressure. If damaged, a cylinder can explode.
Since gas cylinders are normally part of the
welding process, be sure to treat them
carefully.
1. Protect compressed gas cylinders from excessive heat,
mechanical shocks, and arcs.
2. Install and secure cylinders in an upright position by
chaining them to a stationary support or equipment
cylinder rack to prevent falling or tipping.
3. Keep cylinders away from any welding or other
electrical circuits.
4. Never allow a welding electrode to touch any cylinder.
5. Use only correct shielding gas cylinders, regulators,
hoses, and fittings designed for the specific
application; maintain them and associated parts in
good condition.
6. Turn face away from valve outlet when opening
cylinder valve.
7. Keep protective cap in place over valve except when
cylinder is in use or connected for use.
8. Read and follow instructions on compressed gas
cylinders, associated equipment, and CGA publication
P-1 listed in Safety Standards.

ARCMASTER 300 ACDC
1-4 February 22, 2006
WARNING
Engines can be dangerous.
WARNING
ENGINE EXHAUST GASES can kill.
Engines produce harmful exhaust gases.
1. Use equipment outside in open, well-ventilated areas.
2. If used in a closed area, vent engine exhaust outside
and away from any building air intakes.
WARNING
ENGINE FUEL can cause fire or explosion.
Engine fuel is highly flammable.
1. Stop engine before checking or adding fuel.
2. Do not add fuel while smoking or if unit is near any
sparks or open flames.
3. Allow engine to cool before fueling. If possible, check
and add fuel to cold engine before beginning job.
4. Do not overfill tank — allow room for fuel to expand.
5. Do not spill fuel. If fuel is spilled, clean up before
starting engine.
WARNING
MOVING PARTS can cause injury.
Moving parts, such as fans, rotors, and belts can cut
fingers and hands and catch loose clothing.
1. Keep all doors, panels, covers, and guards closed
and securely in place.
2. Stop engine before installing or connecting unit.
3. Have only qualified people remove guards or
covers for maintenance and troubleshooting as
necessary.
4. To prevent accidental starting during servicing,
disconnect negative (-) battery cable from battery.
5. Keep hands, hair, loose clothing, and tools away
from moving parts.
6. Reinstall panels or guards and close doors when
servicing is finished and before starting engine.
WARNING
SPARKS can cause BATTERY GASES TO
EXPLODE; BATTERY ACID can burn eyes and
skin.
Batteries contain acid and generate explosive gases.
1. Always wear a face shield when working on a battery.
2. Stop engine before disconnecting or connecting
battery cables.
3. Do not allow tools to cause sparks when working on
a battery.
4. Do not use welder to charge batteries or jump start
vehicles.
5. Observe correct polarity (+ and –) on batteries.
WARNING
STEAM AND PRESSURIZED HOT COOLANT
can burn face, eyes, and skin.
The coolant in the radiator can be very hot
and under pressure.
1. Do not remove radiator cap when engine is hot. Allow
engine to cool.
2. Wear gloves and put a rag over cap area when
removing cap.
3. Allow pressure to escape before completely removing
cap.

ARCMASTER 300 ACDC
1-5
February 22, 2006
WARNING
This product, when used for welding or
cutting, produces fumes or gases which
contain chemicals know to the State of
California to cause birth defects and, in some
cases, cancer. (California Health & Safety code
Sec. 25249.5 et seq.)
NOTE
Considerations About Welding And The Effects
of Low Frequency Electric and Magnetic Fields
The following is a quotation from the General Conclusions
Section of the U.S. Congress, Office of Technology
Assessment, Biological Effects of Power
Frequency Electric & Magnetic Fields - Background Paper,
OTA-BP-E-63 (Washington, DC: U.S. Government Printing
Office, May 1989): “...there is now a very large volume of
scientific findings based on experiments at the cellular
level and from studies with animals and people which
clearly establish that low frequency magnetic fields and
interact with, and produce changes in, biological systems.
While most of this work is of very high quality, the results
are complex. Current scientific understanding does not
yet allow us to interpret the evidence in a single coherent
framework. Even more frustrating, it does not yet allow
us to draw definite conclusions about questions of
possible risk or to offer clear science-based advice on
strategies to minimize or avoid potential risks.”
To reduce magnetic fields in the workplace, use the
following procedures.
1. Keep cables close together by twisting or taping
them.
2. Arrange cables to one side and away from the
operator.
3. Do not coil or drape cable around the body.
4. Keep welding power source and cables as far away
from body as practical.
ABOUT PACEMAKERS:
The above procedures are among those also
normally recommended for pacemaker
wearers. Consult your doctor for complete
information.
1.02 Principal Safety Standards
Safety in Welding and Cutting, ANSI Standard Z49.1, from
American Welding Society, 550 N.W. LeJeune Rd., Miami,
FL 33126.
Safety and Health Standards, OSHA 29 CFR 1910, from
Superintendent of Documents, U.S. Government Printing
Office, Washington, D.C. 20402.
Recommended Safe Practices for the Preparation for
Welding and Cutting of Containers That Have Held
Hazardous Substances, American Welding Society
Standard AWS F4.1, from American Welding Society, 550
N.W. LeJeune Rd., Miami, FL 33126.
National Electrical Code, NFPA Standard 70, from National
Fire Protection Association, Batterymarch Park, Quincy,
MA 02269.
Safe Handling of Compressed Gases in Cylinders, CGA
Pamphlet P-1, from Compressed Gas Association, 1235
Jefferson Davis Highway, Suite 501, Arlington, VA 22202.
Code for Safety in Welding and Cutting, CSA Standard
W117.2, from Canadian Standards Association, Standards
Sales, 178 Rexdale Boulevard, Rexdale, Ontario, Canada
M9W 1R3.
Safe Practices for Occupation and Educational Eye and
Face Protection, ANSI Standard Z87.1, from American
National Standards Institute, 1430 Broadway, New York,
NY 10018.
Cutting and Welding Processes, NFPA Standard 51B, from
National Fire Protection Association, Batterymarch Park,
Quincy, MA 02269.

ARCMASTER 300 ACDC
1-6 February 22, 2006
1.03 Precautions de Securite en Soudage à L’Arc
MISE EN GARDE
LE SOUDAGE A L’ARC EST DANGEREUX
PROTEGEZ-VOUS, AINSI QUE LES AUTRES, CONTRE LES BLESSURES GRAVES POSSIBLES OU LA MORT. NE LAISSEZ
PAS LES ENFANTS S’APPROCHER, NI LES PORTEURS DE STIMULATEUR CARDIAQUE (A MOINS QU’ILS N’AIENT
CONSULTE UN MEDECIN). CONSERVEZ CES INSTRUCTIONS. LISEZ LE MANUEL D’OPERATION OU LES INSTRUC-
TIONS AVANT D’INSTALLER, UTILISER OU ENTRETENIR CET EQUIPEMENT.
Les produits et procédés de soudage peuvent sauser des blessures graves ou la mort, de même que des dommages
au reste du matériel et à la propriété, si l’utilisateur n’adhère pas strictement à toutes les règles de sécurité et ne prend
pas les précautions nécessaires.
En soudage et coupage, des pratiques sécuritaires se sont développées suite à l’expérience passée. Ces pratiques
doivent être apprises par étude ou entraînement avant d’utiliser l’equipement. Toute personne n’ayant pas suivi un
entraînement intensif en soudage et coupage ne devrait pas tenter de souder. Certaines pratiques concernent les
équipements raccordés aux lignes d’alimentation alors que d’autres s’adressent aux groupes électrogènes.
La norme Z49.1 de l’American National Standard, intitulée “SAFETY IN WELDING AND CUTTING” présente les pra-
tiques sécuritaires à suivre. Ce document ainsi que d’autres guides que vous devriez connaître avant d’utiliser cet
équipement sont présentés à la fin de ces instructions de sécurité.
SEULES DES PERSONNES QUALIFIEES DOIVENT FAIRE
DES TRAVAUX D’INSTALLATION, DE REPARATION,
D’ENTRETIEN ET D’ESSAI.
1.04 Dangers Relatifs au Soudage à L’Arc
AVERTISSEMENT
L’ELECTROCUTION PEUT ETRE MORTELLE.
Une décharge électrique peut tuer ou brûler
gravement. L’électrode et le circuit de soudage
sont sous tension dès la mise en circuit. Le
circuit d’alimentation et les circuits internes
de l’équipement sont aussi sous tension dès
la mise en marche. En soudage automatique
ou semi-automatique avec fil, ce dernier, le
rouleau ou la bobine de fil, le logement des
galets d’entrainement et toutes les pièces
métalliques en contact avec le fil de soudage
sont sous tension. Un équipement
inadéquatement installé ou inadéquatement
mis à la terre est dangereux.
1. Ne touchez pas à des pièces sous tension.
2. Portez des gants et des vêtements isolants, secs et
non troués.
3 Isolez-vous de la pièce à souder et de la mise à la
terre au moyen de tapis isolants ou autres.
4. Déconnectez la prise d’alimentation de l’équipement
ou arrêtez le moteur avant de l’installer ou d’en faire
l’entretien. Bloquez le commutateur en circuit ouvert
ou enlevez les fusibles de l’alimentation afin d’éviter
une mise en marche accidentelle.
5. Veuillez à installer cet équipement et à le mettre à la
terre selon le manuel d’utilisation et les codes
nationaux, provinciaux et locaux applicables.
6. Arrêtez tout équipement après usage. Coupez
l’alimentation de l’équipement s’il est hors d’usage
ou inutilisé.
7. N’utilisez que des porte-électrodes bien isolés. Ne
jamais plonger les porte-électrodes dans l’eau pour
les refroidir. Ne jamais les laisser traîner par terre ou
sur les pièces à souder. Ne touchez pas aux porte-
électrodes raccordés à deux sources de courant en
même temps. Ne jamais toucher quelqu’un d’autre
avec l’électrode ou le porte-électrode.
8. N’utilisez pas de câbles électriques usés,
endommagés, mal épissés ou de section trop petite.
9. N’enroulez pas de câbles électriques autour de votre
corps.

ARCMASTER 300 ACDC
1-7
February 22, 2006
10.N’utilisez qu’une bonne prise de masse pour la mise à
la terre de la pièce à souder.
11.Ne touchez pas à l’électrode lorsqu’en contact avec le
circuit de soudage (terre).
12.N’utilisez que des équipements en bon état. Réparez
ou remplacez aussitôt les pièces endommagées.
13.Dans des espaces confinés ou mouillés, n’utilisez pas
de source de courant alternatif, à moins qu’il soit muni
d’un réducteur de tension. Utilisez plutôt une source
de courant continu.
14.Portez un harnais de sécurité si vous travaillez en hau-
teur.
15.Fermez solidement tous les panneaux et les capots.
AVERTISSEMENT
LE RAYONNEMENT DE L’ARC PEUT BRÛLER
LES YEUX ET LA PEAU; LE BRUIT PEUT
ENDOMMAGER L’OUIE.
L’arc de soudage produit une chaleur et des
rayons ultraviolets intenses, susceptibles de
brûler les yeux et la peau. Le bruit causé par
certains procédés peut endommager l’ouïe.
1. Portez une casque de soudeur avec filtre oculaire de
nuance appropriée (consultez la norme ANSI Z49
indiquée ci-après) pour vous protéger le visage et les
yeux lorsque vous soudez ou que vous observez
l’exécution d’une soudure.
2. Portez des lunettes de sécurité approuvées. Des écrans
latéraux sont recommandés.
3. Entourez l’aire de soudage de rideaux ou de cloisons
pour protéger les autres des coups d’arc ou de
l’éblouissement; avertissez les observateurs de ne pas
regarder l’arc.
4. Portez des vêtements en matériaux ignifuges et
durables (laine et cuir) et des chaussures de sécurité.
5. Portez un casque antibruit ou des bouchons d’oreille
approuvés lorsque le niveau de bruit est élevé.
AVERTISSEMENT
LES VAPEURS ET LES FUMEES SONT
DANGEREUSES POUR LA SANTE.
Le soudage dégage des vapeurs et des fumées
dangereuses à respirer.
Opération de coupage
ou soudage
Dimension d'électrode ou
Epiasseur de métal ou
Intensité de courant
Nuance de
filtre oculaire Opération de coupage ou soudage
Dimension d'électrode ou
Epiasseur de métal ou
Intensité de courant
Nuance de
filtre oculaire
Brassage tendre
au chalumeau toutes conditions 2 Soudage á l'arc sous gaz avec fil plein (GMAW)
Brassage fort
au chalumeau toutes conditions 3 ou 4 métauxnon-ferreux toutes conditions 11
Oxycoupage métauxferreux toutes conditions 12
mince moins de 1 po.(25 mm) 2 ou 3 Soudage á l'arc sous gazavec
électrode de tungstène (GTAW) toutes conditions 12
moyen de 1 á 6 po.(25 á 150 mm) 4 ou 5 Soudage á l'hydrogène
atomique (AHW) toutes conditions 12
épais plus de 6 po.(150 mm) 5 ou 6 Soudage á l'arc avec
électrode de carbone (CAW) toutes conditions 12
Soudage auxgaz Soudage á l'arcPlasma (PAW) toutes dimensions 12
mince moins de 1/8 po.(3 mm) 4 ou 5 Gougeage Air-Arc avec
électrode de carbone
moyen de 1/8 á 1/2 po.(3 á 12 mm) 5 ou 6 mince 12
épais plus de 1/2 po.(12 mm) 6 ou 8 épais 14
Soudage á l'arc avec
électrode enrobees
(SMAW) moins de 5/32 po.(4 mm) 10 Coupage á l'arcPlasma (PAC)
5/32 á 1/4 po. (4 á 6.4 mm) 12 mince moins de 300 amperès 9
plus de 1/4 po.(6.4 mm) 14 moyen de 300 á 400 amperès 12
épais plus de 400 amperès 14
SELECTION DES NUANCES DE FILTRES OCULAIRS POUR LAPROTECTION
DES YEUXEN COUPAGE ET SOUDAGE (selon AWS á 8.2-73)

ARCMASTER 300 ACDC
1-8 February 22, 2006
1. Eloignez la tête des fumées pour éviter de les respirer.
2. A l’intérieur, assurez-vous que l’aire de soudage est
bien ventilée ou que les fumées et les vapeurs sont
aspirées à l’arc.
3. Si la ventilation est inadequate, portez un respirateur
à adduction d’air approuvé.
4. Lisez les fiches signalétiques et les consignes du
fabricant relatives aux métaux, aux produits
consummables, aux revêtements et aux produits
nettoyants.
5. Ne travaillez dans un espace confiné que s’il est bien
ventilé; sinon, portez un respirateur à adduction d’air.
Les gaz protecteurs de soudage peuvent déplacer
l’oxygène de l’air et ainsi causer des malaises ou la
mort. Assurez-vous que l’air est propre à la respira-
tion.
6. Ne soudez pas à proximité d’opérations de
dégraissage, de nettoyage ou de pulvérisation. La
chaleur et les rayons de l’arc peuvent réagir avec des
vapeurs et former des gaz hautement toxiques et irri-
tants.
7. Ne soudez des tôles galvanisées ou plaquées au plomb
ou au cadmium que si les zones à souder ont été
grattées à fond, que si l’espace est bien ventilé; si
nécessaire portez un respirateur à adduction d’air. Car
ces revêtements et tout métal qui contient ces
éléments peuvent dégager des fumées toxiques au
moment du soudage.
AVERTISSEMENT
LE SOUDAGE PEUT CAUSER UN INCENDIE OU
UNE EXPLOSION
L’arc produit des étincellies et des projections.
Les particules volantes, le métal chaud, les
projections de soudure et l’équipement
surchauffé peuvent causer un incendie et des
brûlures. Le contact accidentel de l’électrode
ou du fil-électrode avec un objet métallique
peut provoquer des étincelles, un
échauffement ou un incendie.
1. Protégez-vous, ainsi que les autres, contre les
étincelles et du métal chaud.
2. Ne soudez pas dans un endroit où des particules
volantes ou des projections peuvent atteindre des
matériaux inflammables.
3. Enlevez toutes matières inflammables dans un rayon
de 10, 7 mètres autour de l’arc, ou couvrez-les
soigneusement avec des bâches approuvées.
4. Méfiez-vous des projections brulantes de soudage
susceptibles de pénétrer dans des aires adjacentes
par de petites ouvertures ou fissures.
5. Méfiez-vous des incendies et gardez un extincteur à
portée de la main.
6. N’oubliez pas qu’une soudure réalisée sur un plafond,
un plancher, une cloison ou une paroi peut enflammer
l’autre côté.
7. Ne soudez pas un récipient fermé, tel un réservoir ou
un baril.
8. Connectez le câble de soudage le plus près possible
de la zone de soudage pour empêcher le courant de
suivre un long parcours inconnu, et prévenir ainsi les
risques d’électrocution et d’incendie.
9. Ne dégelez pas les tuyaux avec un source de courant.
10.Otez l’électrode du porte-électrode ou coupez le fil au
tube-contact lorsqu’inutilisé après le soudage.
11.Portez des vêtements protecteurs non huileux, tels
des gants en cuir, une chemise épaisse, un pantalon
revers, des bottines de sécurité et un casque.
AVERTISSEMENT
LES ETINCELLES ET LES PROJECTIONS
BRULANTES PEUVENT CAUSER DES
BLESSURES.
Le piquage et le meulage produisent des
particules métalliques volantes. En
refroidissant, la soudure peut projeter du
éclats de laitier.
1. Portez un écran facial ou des lunettes protectrices
approuvées. Des écrans latéraux sont
recommandés.
2. Portez des vêtements appropriés pour protéger
la peau.

ARCMASTER 300 ACDC
1-9
February 22, 2006
AVERTISSEMENT
LES BOUTEILLES ENDOMMAGEES PEUVENT
EXPLOSER
Les bouteilles contiennent des gaz protecteurs
sous haute pression. Des bouteilles
endommagées peuvent exploser. Comme les
bouteilles font normalement partie du procédé
de soudage, traitez-les avec soin.
1. Protégez les bouteilles de gaz comprimé contre les
sources de chaleur intense, les chocs et les arcs de
soudage.
2. Enchainez verticalement les bouteilles à un support
ou à un cadre fixe pour les empêcher de tomber ou
d’être renversées.
3. Eloignez les bouteilles de tout circuit électrique ou de
tout soudage.
4. Empêchez tout contact entre une bouteille et une
électrode de soudage.
5. N’utilisez que des bouteilles de gaz protecteur, des
détendeurs, des boyauxs et des raccords conçus pour
chaque application spécifique; ces équipements et les
pièces connexes doivent être maintenus en bon état.
6. Ne placez pas le visage face à l’ouverture du robinet
de la bouteille lors de son ouverture.
7. Laissez en place le chapeau de bouteille sauf si en
utilisation ou lorsque raccordé pour utilisation.
8. Lisez et respectez les consignes relatives aux bouteilles
de gaz comprimé et aux équipements connexes, ainsi
que la publication P-1 de la CGA, identifiée dans la
liste de documents ci-dessous.
AVERTISSEMENT
LES MOTEURS PEUVENT ETRE DANGEREUX
LES GAZ D’ECHAPPEMENT DES MOTEURS
PEUVENT ETRE MORTELS.
Les moteurs produisent des gaz d’échappement nocifs.
1. Utilisez l’équipement à l’extérieur dans des aires
ouvertes et bien ventilées.
2. Si vous utilisez ces équipements dans un endroit
confiné, les fumées d’échappement doivent être
envoyées à l’extérieur, loin des prises d’air du bâtiment.
AVERTISSEMENT
LE CARBURANT PEUR CAUSER UN INCENDIE
OU UNE EXPLOSION.
Le carburant est hautement inflammable.
1. Arrêtez le moteur avant de vérifier le niveau e
carburant ou de faire le plein.
2. Ne faites pas le plein en fumant ou proche d’une source
d’étincelles ou d’une flamme nue.
3. Si c’est possible, laissez le moteur refroidir avant de
faire le plein de carburant ou d’en vérifier le niveau au
début du soudage.
4. Ne faites pas le plein de carburant à ras bord: prévoyez
de l’espace pour son expansion.
5. Faites attention de ne pas renverser de carburant.
Nettoyez tout carburant renversé avant de faire
démarrer le moteur.
AVERTISSEMENT
DES PIECES EN MOUVEMENT PEUVENT
CAUSER DES BLESSURES.
Des pièces en mouvement, tels des
ventilateurs, des rotors et des courroies
peuvent couper doigts et mains, ou accrocher
des vêtements amples.
1. Assurez-vous que les portes, les panneaux, les capots
et les protecteurs soient bien fermés.
2. Avant d’installer ou de connecter un système, arrêtez
le moteur.
3. Seules des personnes qualifiées doivent démonter des
protecteurs ou des capots pour faire l’entretien ou le
dépannage nécessaire.

ARCMASTER 300 ACDC
1-10 February 22, 2006
4. Pour empêcher un démarrage accidentel pendant
l’entretien, débranchez le câble d’accumulateur à la
borne négative.
5. N’approchez pas les mains ou les cheveux de pièces
en mouvement; elles peuvent aussi accrocher des
vêtements amples et des outils.
6. Réinstallez les capots ou les protecteurs et fermez les
portes après des travaux d’entretien et avant de faire
démarrer le moteur.
AVERTISSEMENT
DES ETINCELLES PEUVENT FAIRE EXPLOSER
UN ACCUMULATEUR; L’ELECTROLYTE D’UN
ACCUMU-LATEUR PEUT BRULER LA PEAU ET
LES YEUX.
Les accumulateurs contiennent de l’électrolyte
acide et dégagent des vapeurs explosives.
1. Portez toujours un écran facial en travaillant sur un
accumu-lateur.
2. Arrêtez le moteur avant de connecter ou de
déconnecter des câbles d’accumulateur.
3. N’utilisez que des outils anti-étincelles pour travailler
sur un accumulateur.
4. N’utilisez pas une source de courant de soudage pour
charger un accumulateur ou survolter
momentanément un véhicule.
5. Utilisez la polarité correcte (+ et –) de l’accumulateur.
AVERTISSEMENT
LA VAPEUR ET LE LIQUIDE DE
REFROIDISSEMENT BRULANT SOUS
PRESSION PEUVENT BRULER LA PEAU ET
LES YEUX.
Le liquide de refroidissement d’un radiateur
peut être brûlant et sous pression.
1. N’ôtez pas le bouchon de radiateur tant que le moteur
n’est pas refroidi.
2. Mettez des gants et posez un torchon sur le bouchon
pour l’ôter.
3. Laissez la pression s’échapper avant d’ôter
complètement le bouchon.
1.05 Principales Normes de Securite
Safety in Welding and Cutting, norme ANSI Z49.1, American
Welding Society, 550 N.W. LeJeune Rd., Miami, FL 33128.
Safetyand Health Standards, OSHA29 CFR1910,Superintendent
of Documents, U.S. Government Printing Office, Washington, D.C.
20402.
Recommended Safe Practices for the Preparation for Welding and
Cutting of Containers That Have Held Hazardous Substances,
norme AWS F4.1, American Welding Society, 550 N.W. LeJeune
Rd., Miami, FL 33128.
National Electrical Code, norme 70 NFPA, National Fire Protection
Association, Batterymarch Park, Quincy, MA 02269.
Safe Handling of Compressed Gases in Cylinders, document P-1,
CompressedGasAssociation, 1235JeffersonDavisHighway,Suite
501, Arlington, VA 22202.
Code for Safety in Welding and Cutting, norme CSA W117.2
Association canadienne de normalisation, Standards Sales, 276
Rexdale Boulevard, Rexdale, Ontario, Canada M9W 1R3.
Safe Practices for Occupation and Educational Eye and Face
Protection, norme ANSI Z87.1, American National Standards
Institute, 1430 Broadway, New York, NY 10018.
Cutting and Welding Processes, norme 51B NFPA, National Fire
Protection Association, Batterymarch Park, Quincy, MA 02269.

ARCMASTER 300 ACDC
1-11
February 22, 2006
1.06 Limited Warranty
LIMITED WARRANTY: Thermal Arc®, Inc., A Thermadyne Company, hereafter, “Thermal Arc” warrants to customers of itsauthorized distributors
hereafter “Purchaser” that its products will be free of defects in workmanship or material. Should anyfailure to conform to this warranty appear within
the time period applicable to the Thermal Arc products as stated below, Thermal Arc shall, upon notification thereof and substantiation that the product
has been stored, installed, operated, and maintained in accordance with Thermal Arc’s specifications, instructions, recommendations and recognized
standard industry practice, and not subject to misuse, repair, neglect, alteration, or accident, correct such defects by suitable repair or replacement, at
Thermal Arc’s sole option, of any components or parts of the product determined by Thermal Arc to be defective.
THERMAL ARC MAKES NO OTHER WARRANTY, EXPRESS OR IMPLIED. THIS WARRANTY IS EXCLUSIVE AND IN LIEU OF ALL OTHERS, INCLUDING,
BUT NOT LIMITED TO ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE.
LIMITATION OF LIABILITY: THERMAL ARC SHALL NOT UNDER ANY CIRCUMSTANCES BE LIABLE FOR SPECIAL, INDIRECT OR CONSEQUENTIAL
DAMAGES, SUCH AS, BUT NOT LIMITED TO, LOST PROFITS AND BUSINESS INTERRUPTION. The remedies of the Purchaser set forth herein are
exclusive and the liability of Thermal Arc with respect to any contract, or anything done in connection therewith such as the performance or breach
thereof, or from the manufacture, sale, delivery, resale, or use of any goods covered by or furnished by Thermal Arc whether arising out of contract,
negligence, strict tort, or under any warranty, or otherwise, shall not, except as expressly provided herein, exceed the price of the goods upon which
such liability is based. No employee, agent, or representative of Thermal Arc is authorized to change this warranty in any way or grant any other
warranty.
PURCHASER’S RIGHTS UNDER THIS WARRANTY ARE VOID IF REPLACEMENT PARTS OR ACCESSORIES ARE USED WHICH IN THERMAL ARC’S SOLE
JUDGEMENT MAY IMPAIR THE SAFETY OR PERFORMANCE OF ANY THERMAL ARC PRODUCT. PURCHASER’S RIGHTS UNDER THIS WARRANTY ARE
VOID IF THE PRODUCT IS SOLD TO PURCHASER BY NON-AUTHORIZED PERSONS.
The warranty is effective for the time stated below beginning on the date that the authorized distributor delivers the products to the Purchaser.
Notwithstanding the foregoing, in no event shall the warranty period extend more than the time stated plus one year from the date Thermal Arc
delivered the product to the authorized distributor.
POWER SUPPLIES ALL OTHER LABOR
POWER SUPPLIES
MAIN POWER MAGNETICS (STATIC & ROTATING) 3 YEARS 3 YEAR
ORIGINAL MAIN POWER RECTIFIER 3 YEARS 3 YEAR
CONTROL PC BOARD 3 YEARS 3 YEAR
ALL OTHER CIRCUITS AND COMPONENTS INCLUDING BUT
NOT LIMITED TO: CONTACTORS, RELAYS, SOLENOIDS, PUMPS,
POWER SWITCHING SEMI-CONDUCTORS.
ENGINES: ENGINES ARE NOT WARRANTED BY THERMAL ARC,
ALTHOUGH MOST ARE WARRANTED BY THE ENGINE
MANUFACTURER. SEE THE ENGINE MANUFACTURE'S 1 YEAR 1 YEAR
WARRANTY FOR DETAILS.
CONSOLES, CONTROL EQUIPMENT, HEAT EXCHANGES
ACCESSORY EQUIPMENT
1 YEAR 1 YEAR
NOTE: Dragster 85® excluded from this policy. Refer to Dragster 85 warranty in Dragster 85 Owner’s Manual.
Warranty repairs or replacement claims under this limited warranty must be submitted to Thermal Arc by an authorized Thermal Arc repair facility
within thirty (30) days of purchaser’s notice of any Warranty Claim. No transportation costs of any kind will be paid under this warranty. Transportation
charges to send products to an authorized warranty repair facility shall be the responsibility of the Purchaser. All returned goods shall be at the
Purchaser’s risk and expense. This warranty supersedes all previous Thermal Arc warranties. Thermal Arc® is a Registered Trademark of Thermadyne
Industries Inc.
September 27, 2004

ARCMASTER 300 ACDC
1-12 February 22, 2006

ARCMASTER 300 ACDC
February 22, 2006 2-1
SECTION 2:
INTRODUCTION
2.01 How To Use This Manual
This Owner’s Manual applies to just specification or part
numbers listed on page i.
To ensure safe operation, read the entire manual, including
the chapter on safety instructions and warnings.
Throughout this manual, the words WARNING,
CAUTION, and NOTE may appear. Pay particular attention
to the information provided under these headings. These
special annotations are easily recognized as
follows:
!
WARNING
A WARNING gives information regarding
possible personal injury.
CAUTION
A CAUTION refers to possible equipment
damage.
NOTE
A NOTE offers helpful information concerning
certain operating procedures.
Additional copies of this manual may be purchased by
contacting Thermal Arc at the address and phone number
given in the next section. Include the Owner’s Manual
number and equipment identification numbers.
Electronic copies of this manual can also be downloaded
at no charge in Acrobat PDF format by going to the
Thermal Arc web site listed below and clicking on the
Literature Library link:
http://www.thermalarc.com
2.02 Equipment Identification
The unit’s identification number (specification or part
number), model, and serial number usually appear on a
nameplate attached to the control panel. In some cases,
the nameplate may be attached to the rear panel.
Equipment which does not have a control panel such as
gun and cable assemblies is identified only by the
specification or part number printed on the shipping
container. Record these numbers on the bottom of page
1 for future reference.
2.03 Receipt Of Equipment
When you receive the equipment, check it against the
invoice to make sure it is complete and inspect the
equipment for possible damage due to shipping. If there
is any damage, notify the carrier immediately to file a
claim. Furnish complete information concerning damage
claims or shipping errors to the location in your area
listed in the inside back cover of this manual.
Include all equipment identification numbers as described
above along with a full description of the parts in error.
Move the equipment to the installation site before un-
crating the unit. Use care to avoid damaging the
equipment when using bars, hammers, etc., to un-crate
the unit.

ARCMASTER 300 ACDC
2-2 February 22, 2006
2.04 Symbol Chart
Note that only some of these symbols will appear on your model.
Gas Tungsten Arc
Welding (GTAW)
Air Carbon Arc
Cutting (CAC-A)
Constant Current
Constant Voltage
Or Constant Potential
High Temperature
Fault Indication
Arc Force
Touch Start (GTAW)
Variable Inductance
Voltage Input
Single Phase
Three Phase
Three Phase Static
Frequency Converter-
Transformer-Rectifier
Dangerous Voltage
Off
On
Panel/Local
Shielded Metal
Arc Welding (SMAW)
Gas Metal Arc
Welding (GMAW)
Increase/Decrease
Circuit Breaker
AC Auxiliary Power
Remote
Duty Cycle
Percentage
Amperage
Voltage
Hertz (cycles/sec)
Frequency
Negative
Positive
Direct Current (DC)
Protective Earth
(Ground)
Line
Line Connection
Auxiliary Power
Receptacle Rating-
Auxiliary Power
Art # A-04130
115V 15A
t
t1
t2
%
X
IPM
MPM
t
V
Fuse
Wire Feed Function
Wire Feed Towards
Workpiece With
Output Voltage Off.
Preflow Time
Postflow Time
Spot Time
Spot Weld Mode
Continuous Weld
Mode
Press to initiate wirefeed and
welding, release to stop.
Purging Of Gas
Inches Per Minute
Meters Per Minute
Disturbance In
Ground System
Welding Gun
Burnback Time
Press and hold for preflow, release
to start arc. Press to stop arc, and
hold for preflow.
4 Step Trigger
Operation
2 Step Trigger
Operation