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SVM124-A
July, 1996
INVERTEC V250-S
For use with machine Code Numbers 10102 to 10188
Safety Depends on You
Lincoln arc welding and cutting equipment is designed and built with safety in mind. However, your overall safety can be increased by proper installation ... and thoughtful operation on your part. DO NOT INSTALL, OPERATE OR REPAIR THIS EQUIPMENT WITHOUT READING THIS MANUAL AND THE SAFETY PRECAUTIONS CONTAINED THROUGHOUT. And, most importantly, think before you act and be careful.
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SERVICE MANUAL
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World's Leader in Welding and Cutting Products
Premier Manufacturer of Industrial Motors
Sales and Service through Subsidiaries and Distributors Worldwide
22801 St. Clair Ave. Cleveland, Ohio 44117-1199 U.S.A. Tel. (216) 481-8100
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SAFETY
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WARNING
CALIFORNIA PROPOSITION 65 WARNINGS Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm. The Above For Diesel Engines The engine exhaust from this product contains chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. The Above For Gasoline Engines
ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH. KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.
Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you purchase a copy of "Safety in Welding & Cutting - ANSI Standard Z49.1" from the American Welding Society, P.O. Box 351040, Miami, Florida 33135 or CSA Standard W117.2-1974. A Free copy of "Arc Welding Safety" booklet E205 is available from the Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.
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BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE PERFORMED ONLY BY QUALIFIED INDIVIDUALS.
FOR ENGINE powered equipment.
1.a. Turn the engine off before troubleshooting and maintenance work unless the maintenance work requires it to be running. ____________________________________________________ 1.b.Operate engines in open, well-ventilated areas or vent the engine exhaust fumes outdoors.
1.h. To avoid scalding, do not remove the radiator pressure cap when the engine is hot.
____________________________________________________ 1.c. Do not add the fuel near an open flame welding arc or when the engine is running. Stop the engine and allow it to cool before refueling to prevent spilled fuel from vaporizing on contact with hot engine parts and igniting. Do not spill fuel when filling tank. If fuel is spilled, wipe it up and do not start engine until fumes have been eliminated. ____________________________________________________ 1.d. Keep all equipment safety guards, covers and devices in position and in good repair.Keep hands, hair, clothing and tools away from V-belts, gears, fans and all other moving parts when starting, operating or repairing equipment. ____________________________________________________ 1.e. In some cases it may be necessary to remove safety guards to perform required maintenance. Remove guards only when necessary and replace them when the maintenance requiring their removal is complete. Always use the greatest care when working near moving parts. ___________________________________________________ 1.f. Do not put your hands near the engine fan. Do not attempt to override the governor or idler by pushing on the throttle control rods while the engine is running. ___________________________________________________ 1.g. To prevent accidentally starting gasoline engines while turning the engine or welding generator during maintenance work, disconnect the spark plug wires, distributor cap or magneto wire as appropriate.
ELECTRIC AND MAGNETIC FIELDS may be dangerous
2.a. Electric current flowing through any conductor causes localized Electric and Magnetic Fields (EMF). Welding current creates EMF fields around welding cables and welding machines 2.b. EMF fields may interfere with some pacemakers, and welders having a pacemaker should consult their physician before welding. 2.c. Exposure to EMF fields in welding may have other health effects which are now not known. 2.d. All welders should use the following procedures in order to minimize exposure to EMF fields from the welding circuit: 2.d.1. Route the electrode and work cables together - Secure them with tape when possible. 2.d.2. Never coil the electrode lead around your body. 2.d.3. Do not place your body between the electrode and work cables. If the electrode cable is on your right side, the work cable should also be on your right side. 2.d.4. Connect the work cable to the workpiece as close as possible to the area being welded. 2.d.5. Do not work next to welding power source.
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Mar `95
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SAFETY
ELECTRIC SHOCK can kill.
3.a. The electrode and work (or ground) circuits are electrically "hot" when the welder is on. Do not touch these "hot" parts with your bare skin or wet clothing. Wear dry, hole-free gloves to insulate hands.
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ARC RAYS can burn.
4.a. Use a shield with the proper filter and cover plates to protect your eyes from sparks and the rays of the arc when welding or observing open arc welding. Headshield and filter lens should conform to ANSI Z87. I standards. 4.b. Use suitable clothing made from durable flame-resistant material to protect your skin and that of your helpers from the arc rays. 4.c. Protect other nearby personnel with suitable, non-flammable screening and/or warn them not to watch the arc nor expose themselves to the arc rays or to hot spatter or metal.
3.b. Insulate yourself from work and ground using dry insulation. Make certain the insulation is large enough to cover your full area of physical contact with work and ground. In addition to the normal safety precautions, if welding must be performed under electrically hazardous conditions (in damp locations or while wearing wet clothing; on metal structures such as floors, gratings or scaffolds; when in cramped positions such as sitting, kneeling or lying, if there is a high risk of unavoidable or accidental contact with the workpiece or ground) use the following equipment: · Semiautomatic DC Constant Voltage (Wire) Welder. · DC Manual (Stick) Welder. · AC Welder with Reduced Voltage Control. 3.c. In semiautomatic or automatic wire welding, the electrode, electrode reel, welding head, nozzle or semiautomatic welding gun are also electrically "hot". 3.d. Always be sure the work cable makes a good electrical connection with the metal being welded. The connection should be as close as possible to the area being welded. 3.e. Ground the work or metal to be welded to a good electrical (earth) ground. 3.f. Maintain the electrode holder, work clamp, welding cable and welding machine in good, safe operating condition. Replace damaged insulation.
FUMES AND GASES can be dangerous.
5.a. Welding may produce fumes and gases hazardous to health. Avoid breathing these fumes and gases.When welding, keep your head out of the fume. Use enough ventilation and/or exhaust at the arc to keep fumes and gases away from the breathing zone. When welding with electrodes which require special ventilation such as stainless or hard facing (see instructions on container or MSDS) or on lead or cadmium plated steel and other metals or coatings which produce highly toxic fumes, keep exposure as low as possible and below Threshold Limit Values (TLV) using local exhaust or mechanical ventilation. In confined spaces or in some circumstances, outdoors, a respirator may be required. Additional precautions are also required when welding on galvanized steel. 5.b. Do not weld in locations near chlorinated hydrocarbon vapors coming from degreasing, cleaning or spraying operations. The heat and rays of the arc can react with solvent vapors to form phosgene, a highly toxic gas, and other irritating products. 5.c. Shielding gases used for arc welding can displace air and cause injury or death. Always use enough ventilation, especially in confined areas, to insure breathing air is safe. 5.d. Read and understand the manufacturer's instructions for this equipment and the consumables to be used, including the material safety data sheet (MSDS) and follow your employer's safety practices. MSDS forms are available from your welding distributor or from the manufacturer. 5.e. Also see item 1.b.
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3.g. Never dip the electrode in water for cooling. 3.h. Never simultaneously touch electrically "hot" parts of electrode holders connected to two welders because voltage between the two can be the total of the open circuit voltage of both welders. 3.i. When working above floor level, use a safety belt to protect yourself from a fall should you get a shock. 3.j. Also see Items 6.c. and 8.
Mar `95
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SAFETY
WELDING SPARKS can cause fire or explosion.
6.a. Remove fire hazards from the welding area. If this is not possible, cover them to prevent the welding sparks from starting a fire. Remember that welding sparks and hot materials from welding can easily go through small cracks and openings to adjacent areas. Avoid welding near hydraulic lines. Have a fire extinguisher readily available.
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CYLINDER may explode if damaged.
7.a. Use only compressed gas cylinders containing the correct shielding gas for the process used and properly operating regulators designed for the gas and pressure used. All hoses, fittings, etc. should be suitable for the application and maintained in good condition. 7.b. Always keep cylinders in an upright position securely chained to an undercarriage or fixed support. 7.c. Cylinders should be located: · Away from areas where they may be struck or subjected to physical damage. · A safe distance from arc welding or cutting operations and any other source of heat, sparks, or flame. 7.d. Never allow the electrode, electrode holder or any other electrically "hot" parts to touch a cylinder. 7.e. Keep your head and face away from the cylinder valve outlet when opening the cylinder valve. 7.f. Valve protection caps should always be in place and hand tight except when the cylinder is in use or connected for use. 7.g. Read and follow the instructions on compressed gas cylinders, associated equipment, and CGA publication P-l, "Precautions for Safe Handling of Compressed Gases in Cylinders," available from the Compressed Gas Association 1235 Jefferson Davis Highway, Arlington, VA 22202.
6.b. Where compressed gases are to be used at the job site, special precautions should be used to prevent hazardous situations. Refer to "Safety in Welding and Cutting" (ANSI Standard Z49.1) and the operating information for the equipment being used. 6.c. When not welding, make certain no part of the electrode circuit is touching the work or ground. Accidental contact can cause overheating and create a fire hazard.
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6.d. Do not heat, cut or weld tanks, drums or containers until the proper steps have been taken to insure that such procedures will not cause flammable or toxic vapors from substances inside. They can cause an explosion even though they have been "cleaned". For information, purchase "Recommended Safe Practices for the Preparation for Welding and Cutting of Containers and Piping That Have Held Hazardous Substances", AWS F4.1 from the American Welding Society (see address above). 6.e. Vent hollow castings or containers before heating, cutting or welding. They may explode. 6.f. Sparks and spatter are thrown from the welding arc. Wear oil free protective garments such as leather gloves, heavy shirt, cuffless trousers, high shoes and a cap over your hair. Wear ear plugs when welding out of position or in confined places. Always wear safety glasses with side shields when in a welding area.
FOR ELECTRICALLY powered equipment.
8.a. Turn off input power using the disconnect switch at the fuse box before working on the equipment. 8.b. Install equipment in accordance with the U.S. National Electrical Code, all local codes and the manufacturer's recommendations. 8.c. Ground the equipment in accordance with the U.S. National Electrical Code and the manufacturer's recommendations.
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6.g. Connect the work cable to the work as close to the welding area as practical. Work cables connected to the building framework or other locations away from the welding area increase the possibility of the welding current passing through lifting chains, crane cables or other alternate circuits. This can create fire hazards or overheat lifting chains or cables until they fail. 6.h. Also see item 1.c.
Mar `95
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SAFETY
PRÉCAUTIONS DE SÛRETÉ
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Pour votre propre protection lire et observer toutes les instructions et les précautions de sûreté specifiques qui parraissent dans ce manuel aussi bien que les précautions de sûreté générales suivantes: Sûreté Pour Soudage A L'Arc 1. Protegez-vous contre la secousse électrique: a. Les circuits à l'électrode et à la piéce sont sous tension quand la machine à souder est en marche. Eviter toujours tout contact entre les parties sous tension et la peau nue ou les vétements mouillés. Porter des gants secs et sans trous pour isoler les mains. b. Faire trés attention de bien s'isoler de la masse quand on soude dans des endroits humides, ou sur un plancher metallique ou des grilles metalliques, principalement dans les positions assis ou couché pour lesquelles une grande partie du corps peut être en contact avec la masse. c. Maintenir le porte-électrode, la pince de masse, le câble de soudage et la machine à souder en bon et sûr état defonctionnement. d.Ne jamais plonger le porte-électrode dans l'eau pour le refroidir. e. Ne jamais toucher simultanément les parties sous tension des porte-électrodes connectés à deux machines à souder parce que la tension entre les deux pinces peut être le total de la tension à vide des deux machines. f. Si on utilise la machine à souder comme une source de courant pour soudage semi-automatique, ces precautions pour le porte-électrode s'applicuent aussi au pistolet de soudage. 2. Dans le cas de travail au dessus du niveau du sol, se protéger contre les chutes dans le cas ou on recoit un choc. Ne jamais enrouler le câble-électrode autour de n'importe quelle partie du corps. 3. Un coup d'arc peut être plus sévère qu'un coup de soliel, donc: a. Utiliser un bon masque avec un verre filtrant approprié ainsi qu'un verre blanc afin de se protéger les yeux du rayonnement de l'arc et des projections quand on soude ou quand on regarde l'arc. b. Porter des vêtements convenables afin de protéger la peau de soudeur et des aides contre le rayonnement de l`arc. c. Protéger l'autre personnel travaillant à proximité au soudage à l'aide d'écrans appropriés et non-inflammables. 4. Des gouttes de laitier en fusion sont émises de l'arc de soudage. Se protéger avec des vêtements de protection libres de l'huile, tels que les gants en cuir, chemise épaisse, pantalons sans revers, et chaussures montantes.
5. Toujours porter des lunettes de sécurité dans la zone de soudage. Utiliser des lunettes avec écrans lateraux dans les zones où l'on pique le laitier. 6. Eloigner les matériaux inflammables ou les recouvrir afin de prévenir tout risque d'incendie dû aux étincelles. 7. Quand on ne soude pas, poser la pince à une endroit isolé de la masse. Un court-circuit accidental peut provoquer un échauffement et un risque d'incendie. 8. S'assurer que la masse est connectée le plus prés possible de la zone de travail qu'il est pratique de le faire. Si on place la masse sur la charpente de la construction ou d'autres endroits éloignés de la zone de travail, on augmente le risque de voir passer le courant de soudage par les chaines de levage, câbles de grue, ou autres circuits. Cela peut provoquer des risques d'incendie ou d'echauffement des chaines et des câbles jusqu'à ce qu'ils se rompent. 9. Assurer une ventilation suffisante dans la zone de soudage. Ceci est particuliérement important pour le soudage de tôles galvanisées plombées, ou cadmiées ou tout autre métal qui produit des fumeés toxiques. 10. Ne pas souder en présence de vapeurs de chlore provenant d'opérations de dégraissage, nettoyage ou pistolage. La chaleur ou les rayons de l'arc peuvent réagir avec les vapeurs du solvant pour produire du phosgéne (gas fortement toxique) ou autres produits irritants. 11. Pour obtenir de plus amples renseignements sur la sûreté, voir le code "Code for safety in welding and cutting" CSA Standard W 117.2-1974.
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PRÉCAUTIONS DE SÛRETÉ POUR LES MACHINES À SOUDER À TRANSFORMATEUR ET À REDRESSEUR
1. Relier à la terre le chassis du poste conformement au code de l'électricité et aux recommendations du fabricant. Le dispositif de montage ou la piece à souder doit être branché à une bonne mise à la terre. 2. Autant que possible, I'installation et l'entretien du poste seront effectués par un électricien qualifié. 3. Avant de faires des travaux à l'interieur de poste, la debrancher à l'interrupteur à la boite de fusibles. 4. Garder tous les couvercles et dispositifs de sûreté à leur
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Mar. `93
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MASTER TABLE OF CONTENTS FOR ALL SECTIONS
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INSTALLATION .......................................................................................................................SECTION A TECHNICAL SPECIFICATIONS ..................................................................................................A-2 SAFETY PRECAUTIONS ............................................................................................................A-3 SELECT SUITABLE LOCATION..................................................................................................A-3 INPUT CONNECTIONS ...............................................................................................................A-3 INPUT VOLTAGE RECONNECT PROCEDURE.........................................................................A-4 OUTPUT CONNECTIONS ...........................................................................................................A-5 OPERATION .......................................................................................................................SECTION B SAFETY INSTRUCTIONS ...........................................................................................................B-2 GENERAL DESCRIPTION...........................................................................................................B-2 CONTROLS AND SETTINGS......................................................................................................B-3 CONSTANT CURRENT PROCESSES........................................................................................B-4 PARALLEL OPERATION .............................................................................................................B-5 OVERLOAD PROTECTION.........................................................................................................B-5 THERMAL PROTECTION............................................................................................................B-5 ACCESSORIES .......................................................................................................................SECTION C OPTIONS / ACCESSORIES ........................................................................................................C-2 CABLE PLUGS......................................................................................................................C-2 REMOTE CONTROLS ..........................................................................................................C-2 MAINTENANCE .......................................................................................................................SECTION D INPUT FILTER CAPACITOR DISCHARGE PROCEDURE.........................................................D-2 ROUTINE MAINTENANCE..........................................................................................................D-3 FILTER CAPACITOR CONDITIONING ......................................................................................D-3 LOCATION OF MAINTENANCE COMPONENTS.......................................................................D-4 THEORY OF OPERATION .........................................................................................................SECTION E GENERAL DESCRIPTION...........................................................................................................E-2 INPUT LINE VOLTAGE................................................................................................................E-2 PRE-CHARGE AND PROTECTION ............................................................................................E-3 MAIN TRANSFORMER................................................................................................................E-4 OUTPUT RECTIFICATION AND CONTROL...............................................................................E-5 PROTECTION CIRCUITS............................................................................................................E-6 INSULATED GATE BIPOLAR TRANSISTOR (IGBT) OPERATION............................................E-7 PULSE WIDTH MODULATION (PWM)........................................................................................E-8 TROUBLESHOOTING ................................................................................................................SECTION F HOW TO USE TROUBLESHOOTING GUIDE ......................................................................F-2 PC BOARD TROUBLESHOOTING PROCEDURES.............................................................F-3 TROUBLESHOOTING GUIDE...............................................................................................F-4 TEST PROCEDURES..........................................................................................................F-11 REPAIR AND REPLACEMENT PROCEDURES.................................................................F-43 RETEST AFTER REPAIR....................................................................................................F-77 ELECTRICAL DIAGRAMS.........................................................................................................SECTION G
PARTS MANUAL ................................................................................................................................P-244
INVERTEC V250-S
SECTION-A-1
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INSTALLATION
TABLE OF CONTENTS -INSTALLATION SECTION-
SECTION-A-1
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TECHNICAL SPECIFICATIONS ..................................................................................................A-2 SAFETY PRECAUTIONS ............................................................................................................A-3 SELECT SUITABLE LOCATION..................................................................................................A-3 STACKING.............................................................................................................................A-3 TILTING .................................................................................................................................A-3 HIGH FREQUENCY PRECAUTIONS ...................................................................................A-3 INPUT CONNECTIONS ...............................................................................................................A-3 GROUND CONNECTION......................................................................................................A-3 INPUT SUPPLY CONNECTIONS .........................................................................................A-3 POWER INPUT CONNECTION FOR 60HZ MACHINES ......................................................A-3 POWER INPUT CONNECTION FOR 50/60 HZ MACHINES ................................................A-4 INPUT FUSE AND SUPPLY WIRE .......................................................................................A-4 INPUT VOLTAGE RECONNECT PROCEDURE.........................................................................A-4 OUTPUT CONNECTIONS ...........................................................................................................A-5 REMOTE CONTROL RECEPTACLE ....................................................................................A-5 OUTPUT CABLES .................................................................................................................A-5 QUICK DISCONNECT PLUGS..............................................................................................A-5
INVERTEC V250-S
A-2
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INSTALLATION
INPUT THREE PHASE SINGLE PHASE
Model 60Hz 50/60 Hz Standard Input Current at Rated Output Voltage 208/230/460 60Hz 59/57/29 200/220/400/440 50/60 Hz 58/58/30/30
A-2
Technical Specifications - Invertec V250-S
Standard Voltage 208/230/460 200/220/400/440
Input Current at Rated Output 34/32/16 35/33/18/17
Model 60Hz 50/60 Hz
RATED OUTPUT THREE PHASE
Duty Cycle 35% Duty Cycle 60% Duty Cycle 100% Duty Cycle 35% Duty Cycle 60% Duty Cycle 100% Duty Cycle
(1)
SINGLE PHASE
Model 60Hz 60Hz 60Hz 50/60Hz 50/60Hz 50/60Hz Duty Cycle 35% Duty Cycle 60% Duty Cycle 100% Duty Cycle 35% Duty Cycle 60% Duty Cycle 100% Duty Cycle
(1)
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Amps 250 200 165 250 200 165
Volts at Rated Amps 30 28-32 26.5 28-30 29-32 26.5
Amps 250 200 165 250 200 165
Volts at Rated Amps 27-30 28-32 26.5 26-30 28-32 26.5
Model 60Hz 60Hz 60Hz 50/60Hz 50/60Hz 50/60Hz
OUTPUT THREE PHASE
Welding Current Range 1-250 Amps Constant Open Circuit Voltage 65-80 VDC
SINGLE PHASE
Welding Current Range 1-250 Amps Constant Open Circuit Voltage 65-80 VDC
RECOMMENDED INPUT WIRE AND FUSE SIZES THREE PHASE SINGLE PHASE
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Fuse Input (Superlag) Ampere or Rating Breaker on Size Nameplate 50 50 30 50 50 30 30 34 32 16 35 33 18 17 Type 75°C Copper Wire in Conduit AWG (IEC) Sizes 10 (6mm2) 10(6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) Type 75°C Copper Ground Wire in Conduit AWG (IEC) Sizes 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) Fuse Input (Superlag) Ampere or Rating Breaker on Size Nameplate 80 80 40 80 80 40 40 59 57 29 58 58 30 30 Type 75°C Copper Wire in Conduit AWG (IEC) Sizes 8 (10mm2) 8 (10mm2) 10 (6mm2) 8 (16mm2) 8 (16mm2) 10 (6mm2) 10 (6mm2) Type 75°C Copper Ground Wire in Conduit AWG (IEC) Sizes 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2) 10 (6mm2)
Input Voltage Frequency(2) 208/60 230/60 460/60 200/50/60 220/50/60 400/50/60 440/50/60
Input Voltage Frequency(2) 208/60(3) 230/60(3) 460/60 200/50/60 220/50/60 400/50/60 440/50/60
PHYSICAL DIMENSIONS
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Height 15.0 in. 381 mm
(1) Based on a 10 min. period. (2) Input voltage must be within ±10% of rated value. (3) For 1 phase use on 208 or 230 VAC input with output usage above 175A/60% or 200A/35%, the #10 input line cord supplied with the unit should be changed to a #8 or larger conductor cord. () 200 & 208VAC input may not meet NEMA/IEC specifications at 250 Amps.
Width 9.1 in. 231 mm
Depth 19.7 in. 500 mm
Weight 36 lbs. 17 Kg
INVERTEC V250-S
A-3
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INSTALLATION
HIGH FREQUENCY PRECAUTIONS
A-3
Read this entire installation section before you start installation.
SAFETY PRECAUTIONS WARNING
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.
If possible locate the V250-S away from radio controlled machinery. The normal operation of the V250-S may adversely affect the operation of RF controlled equipment, which may result in bodily injury or damage to the equipment.
INPUT CONNECTIONS
The Invertec V250-S should be connected only by a qualified electrician. Installation should be made in accordance with all local and national electric codes and the information detailed below.
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· Be sure to discharge capacitors with the procedure outlined in the Maintenance Section of this manual before working in that area of the equipment.
GROUND CONNECTION
Ground per National Electrical Code for 60Hz machines connect the green lead to earth ground. For 50/60Hz machines connect the ground terminal marked located in the machine on the lower right side the base of the welder to earth ground.
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SELECT SUITABLE LOCATION
The Invertec V250-S will operate in harsh environments. Even so, it is important that simple preventative measures are followed in order to assure long life and reliable operation. · The machine must be located where there is free circulation of clean air such that air movement in the back and out the front will not be restricted. · Dirt and dust that can be drawn into the machine should be kept to a minimum. Failure to observe these precautions can result in excessive operating temperatures and nuisance shutdown. · Keep machine dry. Shelter from rain and snow. Do not place on wet ground or in puddles.
INPUT SUPPLY CONNECTIONS
Be sure the voltage phase and frequency of the input power is as specified on the rating plate, located on the rear of the machine. Supply line entry provision is in the case rear panel.
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POWER INPUT CONNECTION FOR 60HZ MACHINES A 10 ft. power cord is provided and wired into the machine. Follow the power cord connection instructions. Incorrect connection may result in equipment damage.
STACKING
V250-S's cannot be stacked.
Single Phase Input: Connect green lead to ground per U.S. National Electrical Code. Connect black and white leads to power. Wrap red lead with tape to provide 600V insulation. Three Phase Input: Connect green lead to ground per U.S. National Electrical Code. Connect black, red and white leads to power.
TILTING
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INVERTEC V250-S
A-4
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INSTALLATION
INPUT VOLTAGE RECONNECT PROCEDURE
A-4
POWER INPUT CONNECTION FOR 50/60 HZ MACHINES 1. Connect terminal marked to earth ground per National Electric Code. 2. Connect the supply lines to the line switch. Torque to 3.0 Nm. 3. Install in accordance with all local and national electric codes. The Invertec V250-S 50/60 Hz machine is supplied with one cord connector. The cord connector provides a strain relief for the input power cord as it passes it through the rear access hole. The cord connector is designed for a cord diameter of 7.9 to 27.2mm (.310 to 1.070 in).
When received directly from the factory, units are connected for the highest input voltage, 440 VAC for 50/60 Hz machines and 460 VAC for 60 Hz machines. If 440 or 460 VAC is the desired input, then the machine may be connected to the power system without any setup required inside the reconnect door. However, verify the connection with the following procedure. For other voltages refer to the instructions located on the Reconnect Panel Access Door or follow the instructions below.
CAUTION
Failure to follow these instructions can cause immediate failure of components within the welder. -----------------------------------------------------------------------1. Open the access door on the right side of the machine. 2. For 200-230: Position the large switch to 200-230. For 380-460: Position the large switch to 380-460. 3. Move the "A" lead to the appropriate terminal. Refer to figure A.1 below.
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Strip away outer jacket of cord, trim fillers and insert conductors through cord connector. The jacketed portion of the cord must go through the cord connector. Tighten both connector screws.
INPUT FUSE AND SUPPLY WIRE
Refer to the Technical Specifications page at the beginning of this chapter for the proper fuse sizes and supply cable sizes. · Fuse the input circuit with recommended super lag fuses or delay type circuit breakers. · Install the proper fuse in the fuse holder in the main disconnect panel.
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RECONNECT PROCEDURE
1. BE SURE POWER SWITCH IS OFF. 2. CONNECT LEAD 'A' TO DESIRED INPUT VOLTAGE RANGE.
440-460V 380-415V 220-230V 200-208V
. Disconnect input power before
inspecting or servicing machine.
. .
.
A
Do not operate with wraparound removed. Do not touch electrically live parts. Only qualified persons should install, use or service this equipment.
'A'
IF MACHINE CEASES TO OPERATE (NO METER, NO FAN) AND THERE IS NO OTHER KNOWN FAILURE: CHECK FUSE; REPLACE WITH SPECIFIED FUSE.
3. POSITION SWITCH TO DESIRED INPUT VOLTAGE RANGE.
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VOLTAGE=380-460V
VOLTAGE=200-230V
THE LINCOLN ELECTRIC CO.
CLEVELAND, OHIO U.S.A.
S21230
Figure A.1 Input Voltage Reconnect Instructions
INVERTEC V250-S
A-5
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INSTALLATION
QUICK DISCONNECT PLUGS
A-5
OUTPUT CONNECTIONS
Refer to figure A.2 for the location of the 6 Pin Remote Receptacle and the Output Terminals.
A quick disconnect system is used for the welding cable connections. The welding plug included with the machine is designed to accept a welding cable size of 1/0 to 2/0. 1. Remove 1 in. (25mm) of welding cable insulation.
SMAW SOFT
GTAW
SMAW CRISP
THERMAL
HOT START
4 3
5
6 7 8 9
A
6 PIN REMOTE RECEPTACLE
REMOTE LOCAL
85
120 170
2 1 0 10
OUTPUT
50 15 1 250
230
3 2 1
ARC FORCE
4
5
6 7 8 9
2. Slide rubber boot onto cable end. The boot end may be trimmed to match the cable diameter. Soap or other lubricant will help to slide the boot over the cable.
0
10
BOOT
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INVERTEC V250-S
¤
WELDING CABLE
-
+
I
S
25 mm
TRIM
O
1 in.
OUTPUT TERMINALS
3. 4.
Slide the copper tube into the brass plug. Insert cable into copper tube. Tighten set screw to collapse copper tube. Screw must apply pressure against welding cable. The top of the set screw will be well below the surface of the brass plug after tightening.
FIGURE A.2 OUTPUT CONNECTIONS 5.
REMOTE CONTROL RECEPTACLE
Return to Section TOC Return to Master TOC Remote control (K857), Arc start switch (K814), Hand amptrol (K963) and Foot amptrol (K870) connect directly to 6 pin amphenol on the front of the unit.
SET SCREW
OUTPUT CABLES
Select the output cable size based on Table A.1.
BRASS PLUG
TABLE A.1 Cable Sizes for Combined Length of Electrode and Work Cable ( Copper Cable Rated at 75°C). Length up to 150 ft.(46m) up to 250 ft.(72m) Return to Section TOC Return to Master TOC Cable Size 1/0 (50mm2) 2/0 (70mm2) 6.
COPPER TUBE
Slide rubber boot over brass plug. The rubber boot must be positioned to completely cover all electrical surfaces after the plug is locked into the receptacle.
INVERTEC V250-S
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A-6
NOTES
INVERTEC V250-S
A-6
SECTION-B-1
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OPERATION
TABLE OF CONTENTS -OPERATION SECTION-
SECTION-B-1
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SAFETY INSTRUCTIONS ...........................................................................................................B-2 GENERAL DESCRIPTION...........................................................................................................B-2 OPERATIONAL FEATURES .................................................................................................B-2 WELDING CAPABILITY ........................................................................................................B-2 LIMITATIONS ........................................................................................................................B-2 CONTROLS AND SETTINGS......................................................................................................B-3 CONSTANT CURRENT PROCESSES........................................................................................B-4 MANUAL ARC WELDING (STICK)........................................................................................B-4 AIR CARBON ARC CUTTING ...............................................................................................B-4 TIG WELDING .......................................................................................................................B-4 PARALLEL OPERATION .............................................................................................................B-5 OVERLOAD PROTECTION.........................................................................................................B-5 THERMAL PROTECTION............................................................................................................B-5
INVERTEC V250-S
B-2
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OPERATION
GENERAL DESCRIPTION
B-2
Read and understand this entire section before operating your machine.
SAFETY INSTRUCTIONS WARNING
ELECTRIC SHOCK can kill. · Do not touch electrically live parts such as output terminals or internal wiring. · Insulate yourself from the work and ground.
The Invertec V250-S is a 250 amp arc welding power source that utilizes single or three phase input power, to produce constant current output. The welding response of this Invertec has been optimized for stick (SMAW) and TIG (GTAW).
OPERATIONAL FEATURES
The Invertec V250-S provides continuous total range output current adjustment, selectable welding modes and local or remote output control. Welding characteristics can be controlled via an arc force control. Additionally, starting characteristics can be adjusted via a "hot start" control.
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· Always wear dry insulating gloves.
____________________________________
FUMES AND GASES can be dangerous. · Keep your head out of fumes. · Use ventilation or exhaust to remove fumes from breathing zone.
WELDING CAPABILITY
The Invertec V250-S is rated at 250 amps, 35% duty cycle (based on a 10 minute cycle). It is also rated at 165 amps, 100% duty cycle, and 200 amps, 60% duty cycle.
LIMITATIONS
The V250-S is not recommended for pipe thawing. The V250-S should not be powered from the auxiliary power supply of an engine welder. Special protection circuits may operate causing loss of output.
____________________________________
WELDING, CUTTING and GOUGING SPARKS can cause fire or explosion Return to Section TOC Return to Master TOC · Keep flammable material away. · Do not weld, cut or gouge on containers that have held combustibles.
____________________________________
ARC RAYS can burn. · Wear eye, ear and body protection.
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____________________________________
Only qualified personnel should operate this equipment. Observe all safety information throughout this manual.
INVERTEC V250-S
B-3
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OPERATION
B-3
CONTROLS AND SETTINGS
All operator controls and adjustments are located on the case front of the V250-S. Refer to Figure B.1 and corresponding explanations. FIGURE B.1 -- CASE FRONT CONTROLS.
4
8
SMAW SOFT GTAW SMAW CRISP THERMAL
HOT START
2
A
4 3
5
6 7 8 9
85
120 170
2 1 0 10
OUTPUT
5
3
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REMOTE LOCAL
50 15 1 250
230
3 2 1
ARC FORCE
4
5
6 7 8 9
6
0
10
INVERTEC V250-S
®
-
+
I
S
1
O
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7
1. Power Switch - Place the lever in the "ON" position to energize the machine. When the power is on, the fan will operate and the output will be energized in SMAW modes. GTAW mode requires remote trigger to energize the output. 2. Output Control - This controls the output current. Control is provided over the entire output range of the power source with 1 turn of the control knob. This control may be adjusted while under load to change power source output. When using remote control this function becomes the limit setting. 3. Local/Remote Switch - Place in the "LOCAL" position to allow output adjustment at the machine. Place in the "REMOTE" position to allow output adjustment at remote pot or amptrol. In Remote, the machine output control pot is the limit setting for remote control. 4. Mode Switch GTAW Optimized for touch start use. Triggering at amphenol is required using an Arc Start Switch, Amptrol or similar means. Short circuit current is limited to approximately 25 amps to aid in touch starting.
CC Soft Best for EXX18 thru EXX28 stick electrodes. Output energized when machine is on. CC Crisp Use this mode for stick welding with EXX10 thru EXX14 electrodes. Output energized when machine is on.
5. Hot Start - Controls the amount of starting energy in SMAW.
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INVERTEC V250-S
B-4
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OPERATION
MANUAL ARC WELDING (STICK)
B-4
6. Arc Force - This control functions in SMAW modes to adjust the Arc Force. The arc is soft at the minimum settings and more forceful or driving at the maximum settings. Higher spatter levels may be present at the maximum settings. RECOMMENDED ARC FORCE/INDUCTANCE SETTINGS FOR SELECTED APPLICATIONS FULL RANGE IS 1-10. 1 is VERY SOFT, 10 IS VERY CRISP Nominal Setting
5
CONSTANT CURRENT PROCESSES
The Invertec may be utilized as a manual DC arc welder with the electrode cable, work cable, and electrode holder being the only equipment required.
AIR CARBON ARC CUTTING
Air carbon arc cutting may be performed with the Invertec within its output rating using 5/32" (3.9mm) and 3/16" (4.7mm) diameter carbon rods. Output cables, an air carbon arc electrode cable assembly, and a source of compressed air are required. NOTE: 1. Best performance will be at settings of 200 amps and below. 2. The electronic protection circuit in the V250S will limit the current to approximately 290 amps.
Mode
CC SMAW 1 (soft) CC SMAW 2 (crisp)
Process
EXX18 thru EXX28 stick EXX10 thru EXX14 stick Air Carbon Arc Cutting
Recommended Adjustment Range
1 (gentle, may stick) to 9 (forceful, more spatter) 3 to 10
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6
1
None
7. Output Terminals - These quick disconnect terminals provide connection points for the electrode and work cables. Refer to Output Connections in the Installation chapter for proper cable sizes. For positive polarity welding connect the electrode cable to the positive terminal and the work cable to the negative terminal. To weld negative polarity reverse the electrode and work cables. 8. Thermal Shutdown Indicator - This light will illuminate if an internal thermostat has been activated. Machine output will return after the internal components have returned to a normal operating temperature. See Thermal Protection later in this chapter.
TIG WELDING
The V250S is capable of touch start TIG welding. An electrode cable, work cable, Arc Start Switch or Amptrol, TIG torch, and gas supply with regulator are required. Refer to Accessories section of this manual. Touch starting is done as follows: 1. Place the shield cup edge on the work piece. 2. Rock the tungsten down to touch. 3. Trigger the output. 4. Gently rock back the tungsten from the workpiece. Note: The short circuit current is limited to 25 amps to aid in touch starting. Panel output control becomes the current limit setting when in remote control
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INVERTEC V250-S
B-5
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OPERATION
B-5
PARALLEL OPERATION
The Invertec's are operable in parallel. For best results, the currents of each machine should be reasonably well shared. As an example, with two machines set up in parallel for a 300 amp procedure, each machine should be set to deliver approximately 150 amps, not 200 amps from one and 100 amps from the other. This will minimize nuisance feedback conditions. In general, more than two machines in parallel will not be effective due to the voltage requirements of procedures in that power range. To set machine outputs, start with output control pots and arc force pots in identical positions. Adjust outputs and arc forces to maintain current sharing while establishing the proper output current.
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OVERLOAD PROTECTION
The machine is electrically protected from producing high output currents. Should the output current exceed 290A, an electronic protection circuit will reduce the current to less than 200A. The machine will continue to produce this low current until the protection circuit is reset. Reset occurs when the output load is removed.
THERMAL PROTECTION
Return to Section TOC Thermostats protect the machine from excessive operating temperatures. Excessive temperatures may be caused by a lack of cooling air or operating the machine beyond the duty cycle and output rating. If excessive operating temperature should occur, the thermostats will prevent output voltage or current. Thermostats are self-resetting once the machine cools sufficiently. If the thermostat shutdown was caused by excessive output or duty cycle and the fan is operating normally, the Power Switch may be left on and the reset should occur within a 15 minute period. If the fan is not turning or the air intake louvers were obstructed, then the power must be switched off for 15 minutes in order to reset. The fan problem or air obstruction must also be corrected.
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INVERTEC V250-S
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B-6
NOTES
INVERTEC V250-S
B-6
SECTION C-1
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ACCESSORIES
TABLE OF CONTENTS -ACCESSORIES SECTION-
SECTION C-1
OPTIONS / ACCESSORIES ........................................................................................................C-2 CABLE PLUGS......................................................................................................................C-2 K852-70 .......................................................................................................................C-2 K852-95 .......................................................................................................................C-2 REMOTE CONTROLS ..........................................................................................................C-2 K857.............................................................................................................................C-2 K963 ............................................................................................................................C-2 K870.............................................................................................................................C-2 K814 ............................................................................................................................C-2
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INVERTEC V250-S
C-2
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ACCESSORIES
C-2
OPTIONS / ACCESSORIES
CABLE PLUGS
K852-70 - Cable Plug Kit for 1/0-2/0 cable. Attaches to welding cable to provide quick disconnect from machine. K852-95 - Cable Plug Kit for 2.0-3/0 cable. NOTE: Two K852-70 plugs are included with the V250-S.
REMOTE CONTROLS
Return to Section TOC Return to Master TOC Return to Master TOC Return to Master TOC K857 - Remote Output Control for stick welding. K963 - Hand Amptrol tm for TIG welding. When the V250-S's Output Control is in the "Remote" position, the hand Amptrol energizes the output and controls the output remotely. The Hand Amptrol connects directly to the 6 pin Amphenol. K870 - Foot Amptrol tm for TIG welding. When the V250-S's Output Control is in the "REMOTE" position, the foot Amptrol energizes the output and controls the output remotely. The Hand Amptrol connects directly to the 6 pin Amphenol.
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K814 - Arc Start Switch. Energizes the output for TIG welding if remote output control of the amperage is not desired. When using the Arc Start Switch set the Output Control to the "LOCAL" position.
INVERTEC V250-S
SECTION D-1
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MAINTENANCE
TABLE OF CONTENTS -MAINTENANCE SECTION-
SECTION D-1
INPUT FILTER CAPACITOR DISCHARGE PROCEDURE.........................................................D-2 ROUTINE MAINTENANCE..........................................................................................................D-3 FILTER CAPACITOR CONDITIONING ......................................................................................D-3 LOCATION OF MAINTENANCE COMPONENTS.......................................................................D-4
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INVERTEC V250-S
D-2
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MAINTENANCE
WARNING
ELECTRIC SHOCK can kill.
D-2
· 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. · Prior to Performing preventative maintenance, perform the following capacitor discharge procedure to avoid electric shock. ---------------------------------------------------------------------
4. Obtain a high resistance and high wattage resistor (25-1000 ohms and 25 watts minimum). This resistor is not supplied with machine. NEVER USE A SHORTING STRAP FOR THIS PROCEDURE. 5. Locate the four capacitor terminals (large hex head cap screws) shown in Figure D.1. One pair at the top and one pair at the bottom of the Power Board. 6. Use electrically insulated gloves and insulated pliers. Hold body of the resistor and connect resistor leads across the two capacitor terminals. Hold resistor in place for 10 seconds. DO NOT TOUCH CAPACITOR TERMINALS WITH YOUR BARE HANDS. 7. Repeat discharge procedure for the capacitor on other two terminals. 8. Check voltage across terminals of all capacitors with a DC voltmeter. Polarity of capacitor terminals is marked on PC board above terminals. Voltage should be zero. If any voltage remains, repeat this capacitor discharge procedure.
INPUT FILTER CAPACITOR DISCHARGE PROCEDURE
Return to Section TOC Return to Master TOC 1. Turn off input power or disconnect input power lines. 2. Remove the 5/16" hex head screws from the side and top of the machine and remove wrap-around machine cover. 3. Be careful not to make contact with the capacitor terminals that are located in the top and bottom of the Power Board.
FIGURE D.1 -- LOCATION OF INPUT FILTER CAPACITOR TERMINALS. Return to Section TOC Return to Master TOC
POWER BOARD UPPER CAPACITOR TERMINALS
LOWER CAPACITOR TERMINALS POWER RESISTOR
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RIGHT SIDE OF MACHINE
INSULATED PLIERS
INSULATED GLOVES
INVERTEC V250-S
D-3
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MAINTENANCE
FILTER CAPACITOR CONDITIONING
D-3
ROUTINE MAINTENANCE
1. Perform the following preventive maintenance procedures at least once every six months. It is good practice to keep a preventive maintenance record; a record tag attached to the machine works best. Remove the machine wrap-around cover and perform the input filter capacitor discharge procedure (detail at the beginning of this chapter). Keeping the machine clean will result in cooler operation and higher reliability. Be sure to clean the following areas with a low pressure air stream. See figure D.2 for component locations. Power and control printed circuit boards Power switch Main transformer Input rectifier Heat sink fins · Input Filter Capacitors · Output Terminals 4. Examine capacitors for leakage or oozing. Replace if needed. 5. Examine the sheet metal case for dents or breakage. Repair the case as required. Keep the case in good condition to ensure that high voltage parts are protected and correct spacings are maintained. All external sheet metal screws must be in place to assure case strength and electrical ground continuity.
2.
A protection circuit is included to monitor the voltage across filter capacitors C1 and C2. In the event that the capacitor voltage is too high, the protection circuit will prevent output. Nominal trip setting is at 230/460 VAC +15%. Reset occurs about 3% lower (230/460 VAC +12%). On new installations, the protection circuit may also prevent output providing all these circumstances are met: 1. Machine is connected for 380-415 or 440-460 VAC input. 2. Machine did not have power applied for many months. 3. Machine will not produce output when power is first switched on. If these circumstances apply, the proper action is to switch the machine on and let it idle for up to 30 minutes. This is required to condition the filter capacitors after an extended storage time. The protection circuit will automatically reset once the capacitor conditioning and resultant voltage levels are acceptable. It may be necessary to turn the power switch off and back on again after this period.
3.
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· · · · ·
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6. Check electrical ground continuity. Using an ohmmeter, measure resistance between either output terminal and an unpainted surface of the machine case. (See Figure D.2 for locations.) Meter reading should be 500,000 ohms or more. If meter reading is less than 500,000 ohms, check for electrical components that are not properly insulated from the case. Correct insulation if needed. 7. Replace machine cover and screws.
INVERTEC V250-S
D-4
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MAINTENANCE
FIGURE D.2 -- LOCATION OF MAINTENANCE COMPONENTS.
D-4
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CONTROL PC BOARD
INPUT RECTIFIER
POWER PC BOARD POWER SWITCH
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COOLING FANS OUTPUT TERMINALS OUTPUT RECTIFIER HEATSINK FINS
MAIN TRANSFORMER
AUXILIARY TRANSFORMER
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INVERTEC V250-S
E-1 Return to Master TOC
THEORY OF OPERATION
TABLE OF CONTENTS -THEORY OF OPERATION SECTIONGENERAL DESCRIPTION...........................................................................................................E-2 INPUT LINE VOLTAGE................................................................................................................E-2 PRE-CHARGE AND PROTECTION ............................................................................................E-3 MAIN TRANSFORMER................................................................................................................E-4 OUTPUT RECTIFICATION AND CONTROL...............................................................................E-5 PROTECTION CIRCUITS............................................................................................................E-6 INSULATED GATE BIPOLAR TRANSISTOR (IGBT) OPERATION............................................E-7 PULSE WIDTH MODULATION (PWM)........................................................................................E-8
E-1
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INVERTEC V250-S
E-2 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
E-2
GENERAL DESCRIPTION
The Invertec V250-S is a 250 amp arc welding power source that utilizes either single or three phase input power to produce a constant current output. The output response of this machine has been optimized for the SMAW and TIG welding processes. FIGURE E.1 - INPUT VOLTAGE CIRCUITS
POWER BOARD INPUT RECTIFIER
CR1 RELAY
MAIN TRANSFORMER
INPUT LINE SWITCH
IGBT
R E C O N N E C T S W I T C H
CAPACITOR
POSITIVE OUTPUT TERMINAL
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IGBT
SHUNT
IGBT
CURRENT TRANSFORMER
CAPACITOR
IGBT
"A" L E A D
FAN MOTORS
O V E R V O L T A G E
F E E D B A C K
THERMOSTATS
F E E D B A C K
NEGATIVE OUTPUT TERMINAL
IGBT GATE SIGNALS PROTECTION SIGNAL
CR1 RELAY DRIVE SIGNAL
CONTROL BOARD
THERMAL LIGHT
18VAC
AUXILIARY TRANSFORMER REMOTE RECEPTACLE
OUTPUT STRIKE ARC MODE LOCAL/ CONTROL CONTROL FORCE SWITCH REMOTE SWITCH CONTROL
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INPUT LINE VOLTAGE
The single-phase or three-phase input power of 208, 230 or 460 volts AC is connected to the machine, through a line switch located on the front panel. A reconnect panel and switch allows the user to configure the machine for either a low or high input voltage and also connect the auxiliary transformer for the appropriate input voltage.
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The auxiliary transformer develops the appropriate AC voltages to operate the cooling fans and the control board.
NOTE: Unshaded areas of block logic diagrams are the subject of discussion. INVERTEC V250-S
E-3 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
FIGURE E.2 PROTECTION AND PRE-CHARGE CIRCUITS
E-3
POWER BOARD INPUT RECTIFIER
CR1 RELAY
MAIN TRANSFORMER
INPUT LINE SWITCH
IGBT
R E C O N N E C T S W I T C H
CAPACITOR
POSITIVE OUTPUT TERMINAL
IGBT
SHUNT
IGBT
CURRENT TRANSFORMER
CAPACITOR
IGBT
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"A" L E A D
FAN MOTORS
O V E R V O L T A G E
F E E D B A C K
THERMOSTATS
F E E D B A C K
NEGATIVE OUTPUT TERMINAL
IGBT GATE SIGNALS PROTECTION SIGNAL
CR1 RELAY DRIVE SIGNAL
CONTROL BOARD
THERMAL LIGHT
18VAC
AUXILIARY TRANSFORMER REMOTE RECEPTACLE
OUTPUT STRIKE ARC MODE LOCAL/ CONTROL CONTROL FORCE SWITCH REMOTE SWITCH CONTROL
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PRECHARGE AND PROTECTION
The input voltage is rectified and the DC voltage is applied, through the reconnect switch, to the power board. The power board contains precharging circuitry for the safe charging of the input filter capacitors. Once the capacitors are precharged and balanced the control board activates the CR1 input relay which connects full input power to the filter capacitors. When the filter capacitors are fully charged they act as power supplies for the IGBT switching circuit. The Insulated Gate Bipolar Transistors supply the main transformer primary windings with DC current flow. See IGBT Operation Discussion and diagrams in this section. The power board also monitors the filter capacitors for voltage balance and/or overvoltage and, if either should occur, sends the appropriate signal to the control board to deactivate the CR1 input relay. The machine output will also be disabled.
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NOTE: Unshaded areas of block logic diagrams are the subject of discussion. INVERTEC V250-S
E-4 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
FIGURE E.3 MAIN TRANSFORMER
E-4
POWER BOARD INPUT RECTIFIER
CR1 RELAY
MAIN TRANSFORMER
INPUT LINE SWITCH
IGBT
R E C O N N E C T S W I T C H
CAPACITOR
POSITIVE OUTPUT TERMINAL
IGBT
SHUNT
IGBT
CURRENT TRANSFORMER
CAPACITOR
IGBT
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"A" L E A D
FAN MOTORS
O V E R V O L T A G E
F E E D B A C K
THERMOSTATS
F E E D B A C K
NEGATIVE OUTPUT TERMINAL
IGBT GATE SIGNALS PROTECTION SIGNAL
CR1 RELAY DRIVE SIGNAL
CONTROL BOARD
THERMAL LIGHT
18VAC
AUXILIARY TRANSFORMER REMOTE RECEPTACLE
OUTPUT STRIKE ARC MODE LOCAL/ CONTROL CONTROL FORCE SWITCH REMOTE SWITCH CONTROL
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MAIN TRANSFORMER
Each IGBT pair acts as a switch assembly. Each assembly feeds a separate, oppositely wound primary winding of the main transformer. The reverse directions of current flow through the main transformer primaries and the offset timing of the IGBT pairs induce an AC square wave output signal at the secondary of the main transformer. The DC current flow through each primary winding is redirected or "clamped" back to each respective filter capacitor when the IGBTs are turned off. This is needed due to the inductance of the transformer primary winding. The primary currents also pass through the current transformer which sends a signal to the control board. If the primary currents are not equal the control board compensates by adjusting the IGBT gate signals. The firing of both IGBT pairs occurs during halves of the 50 microsecond intervals, creating a constant 20 KHZ output.
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NOTE: Unshaded areas of block logic diagrams are the subject of discussion. INVERTEC V250-S
E-5 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
FIGURE E.4 OUTPUT RECTIFICATION AND CONTROL
E-5
POWER BOARD INPUT RECTIFIER
CR1 RELAY
MAIN TRANSFORMER
INPUT LINE SWITCH
IGBT
R E C O N N E C T S W I T C H
CAPACITOR
POSITIVE OUTPUT TERMINAL
IGBT
SHUNT
IGBT
CURRENT TRANSFORMER
CAPACITOR
IGBT
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"A" L E A D
FAN MOTORS
O V E R V O L T A G E
F E E D B A C K
THERMOSTATS
F E E D B A C K
NEGATIVE OUTPUT TERMINAL
IGBT GATE SIGNALS PROTECTION SIGNAL
CR1 RELAY DRIVE SIGNAL
CONTROL BOARD
THERMAL LIGHT
18VAC
AUXILIARY TRANSFORMER REMOTE RECEPTACLE
OUTPUT STRIKE ARC MODE LOCAL/ CONTROL CONTROL FORCE SWITCH REMOTE SWITCH CONTROL
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OUTPUT RECTIFICATION AND CONTROL
The AC output from the main transformer secondary is rectified to a DC output and applied to the output terminals. Output voltage and current feedback information, which is fed to the control board, is sensed at the output terminals and shunt. The control board monitors the panel controls and remote control receptacle and compares these commands to the feedback information to determine how the output should be controlled to optimized welding results. The control board controls the IGBT switching through pulse width modulation circuitry. See IGBT Operation Discussion in this section.
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NOTE: Unshaded areas of block logic diagrams are the subject of discussion. INVERTEC V250-S
E-6 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
E-6
PROTECTION CIRCUITS
Protective circuits are designed into the V250-S machine to sense trouble and shut down the machine before the trouble damages the internal machine components. Both overload and thermal protection circuits are included.
OVERLOAD PROTECTION
The V250-S is electrically protected from producing high output currents. Should the output current exceed 290 amps, an electronic protection circuit will reduce the current to less than 200 amps. Lincoln Electric refers to this current reduction as "Fold Back". The machine will continue to produce this low current until the protection circuit is reset. Reset occurs when the output load is removed. A protection circuit is included to monitor the voltage across the input filter capacitors. In the event that the capacitor voltage is too high, the protection circuit will prevent output. On new installations, the protection circuit may prevent output, due to unbalanced capacitor leakages, providing the following circumstances are met: 1. Machine is connected for 380 - 460VAC input. 2. Machine did not have power applied for many months. 3. Improper connections. 4. Internal component damage.
THERMAL PROTECTION
Thermostats protect the machine from excessive operating temperatures. Excessive temperatures may be caused by a lack of cooling air or operating the machine beyond the duty cycle and output rating. If excessive operating temperature should occur, the thermostat will prevent output voltage or current and the thermal indicator light will glow. Thermostats are self-resetting once the machine cools sufficiently. If the thermostat shutdown was caused be excessive output or duty cycle and the fan is operating normally, the power switch may be left on and the reset should occur within 15 minute period. If the fan is not turning or the air intake louvers were obstructed, then the power must be switched off for 15 minutes in order to reset. The fan problem or air obstruction must be corrected.
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NOTE: Unshaded areas of block logic diagrams are the subject of discussion. INVERTEC V250-S
E-7 Return to Section TOC Return to Master TOC
THEORY OF OPERATION
E-7
INSULATED GATE BIPOLAR TRANSISTOR (IGBT) OPERATION
An IGBT is a type of tr