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IM575
MASTER LOAD™ 750
May, 2006
For use with equipment code number 10401.
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 thought-
ful 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.
OPERATORS MANUAL
Copyright © 2005 Lincoln Global Inc.
• World's Leader in Welding and Cutting Products •
• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com
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WELDING EQUIPMENT SAFETY
ARC RAYS can burn.
ELECTRIC SHOCK can
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.
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.
4.b. Use suitable clothing made from durable flame-resistant
material to protect your skin and that of your helpers from
the arc rays.
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.
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.
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:
FUMES AND GASES
can be dangerous.
5.a. Welding may produce fumes and gases
hazardous to health. Avoid breathing these
• Semiautomatic DC Constant Voltage (Wire) Welder.
• DC Manual (Stick) Welder.
fumes and gases.When welding, keep
your head out of the fume. Use enough
• AC Welder with Reduced Voltage Control.
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.
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.
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.
3.f. Maintain the electrode holder, work clamp, welding cable and
welding machine in good, safe operating condition. Replace
damaged insulation.
3.g. Never dip the electrode in water for cooling.
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.
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.
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.
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.
5.e. Also see item 1.b.
Mar ‘95
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WELDING EQUIPMENT SAFETY
WELDING SPARKS can
CYLINDER may explode
if damaged.
cause fire or explosion.
6.a. Remove fire hazards from the welding area.
If this is not possible, cover them to prevent
7.a. Use only compressed gas cylinders
containing the correct shielding gas for the
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.
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.
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.
7.c. Cylinders should be located:
•Away from areas where they may be struck or subjected to
physical damage.
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.
•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.
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).
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.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.
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 cir-
cuits. This can create fire hazards or overheat lifting chains
or cables until they fail.
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.
6.h. Also see item 1.c.
8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.
Mar ‘95
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WELDING EQUIPMENT SAFETY
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.
PRÉCAUTIONS DE SÛRETÉ
Pour votre propre protection lire et observer toutes les instruc-
tions et les précautions de sûreté specifiques qui parraissent
dans ce manuel aussi bien que les précautions de sûreté
générales suivantes:
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.
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.
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 lev-
age, 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.
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.
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 forte-
ment toxique) ou autres produits irritants.
e. Ne jamais toucher simultanément les parties sous tension
des porte-électrodes connectés à deux machines à soud-
er 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.
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.
2. Dans le cas de travail au dessus du niveau du sol, se pro-
téger 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.
PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR
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.
1. Relier à la terre le chassis du poste conformement au code
de l’électricité et aux recommendations du fabricant. Le dis-
positif de montage ou la piece à souder doit être branché à
une bonne mise à la terre.
c. Protéger l’autre personnel travaillant à proximité au
soudage à l’aide d’écrans appropriés et non-inflamma-
bles.
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. 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.
4. Garder tous les couvercles et dispositifs de sûreté à leur
place.
Mar. ‘93
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LOAD BANK SAFETY
The load bank is an industrial test unit designed to be
used indoors or outdoors (sheltered from moisture).
However, because the nature of the load bank’s func-
tion is the dissipation of electrical energy, electrical
energy is transformed into heat by the resistor ele-
ments. The heat is removed from the load bank by
airflow through the resistor elements. If there are any
restrictions or stoppage of airflow, the load bank may
overheat. For safe operation the following recommen-
dations should be observed:
7. Allow cool room air to pass into the unit to cool
the elements. Do not allow the unit to be placed
where hot exhaust air can recirculate back
through the unit causing a constant rise in cooling
air temperature.
8. After running a load test, residual heat may be
removed from the load bank by allowing the blow-
er to operate for a few minutes after load is
removed. This procedure is not required for load
bank integrity, but it may guard operating person-
nel from possible burn injuries.
1. Read the manual before operating the Load Bank.
9. The operator should avoid coming in contact with
the resistor elements or surrounding covers during
and for some time after operation. These por-
tions of the load bank become hot .
2. Run an approved ground wire from the Load Bank
ground lug located on the connection panel to the
frame of the power source. Run an approved
ground wire from the power source frame to a
good earth ground. Size ground wire in accor-
dance with National Electrical Code and any local
codes.
10. Do not allow objects to enter or block the air
intake or exhaust of the load bank. A blockage
would cause overheating. If an object enters the
screens, it may cause damage to the resistor ele-
ments, possibly shorting them and causing shock
and fire hazards.
3. Do not bypass the airflow safety switch or temper-
ature sensing switch to prevent nuisance tripping.
The switches will drop out the load if insufficient
cooling air is reaching the elements.
11. Emergency Shutdown Procedure
4. Replace any burned out lamps on the control
panel. Each lamp is an indication that a system
is active or has failed and is important to the oper-
ation of the unit and safety of the operator.
A. In an emergency, shut down the MASTER
LOAD switch, then the power source. The
MASTER LOAD switch will allow disconnec-
tion of all load steps and still allow for the fan
motor to run, cooling any heated elements.
B. The POWER ON/OFF switch will disconnect
both load steps and fan motor. The power
source EMERGENCY OFF switch should be
located near the load system.
WARNING
ELECTRIC SHOCK can kill.
Personal injury from electrical shock
may result if all sources of power are
not disconnected before servicing.
Only qualified personnel should
Install, Operate and Service this equip-
ment.
12. An approved electrical fire extinguisher should be
on hand at all times.
13. It is the responsibility of the customer to take dili-
gent care in installing the Load Bank. The
National Electrical Code (NEC), sound local elec-
trical and safety codes, and the Occupational
Safety and Health Act (OSHA) should be followed
when installing the equipment to reduce hazards
to persons and property.
------------------------------------------------------------------------
5. Maintenance should be performed with no power
on the unit. The majority of troubleshooting can
be performed with an ohmmeter. There are mul-
tiple sources of input power to the Load Bank.
Insure each is disconnected.
14. Flammable objects (cardboard, paper, etc.) must
not be stored near the load bank
6. Venting the heated air from the exhaust toward
overhead cables, sprinkler systems, or into a
room with insufficient volume or "Make-Up" air, is
a potential hazard. The Load Bank should be
used in a cool, well-ventilated area.
15. As part of your safety program, an initial inspec-
tion after receiving the unit(s) and periodic preven-
tive maintenance and safety inspections should
be conducted to insure the reliability and safety.
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for selecting a QUALITY product by Lincoln Electric. We want you
to take pride in operating this Lincoln Electric Company product
••• as much pride as we have in bringing this product to you!
Thank You
Please Examine Carton and Equipment For Damage Immediately
When this equipment is shipped, title passes to the purchaser upon receipt by the carrier. Consequently, Claims
for material damaged in shipment must be made by the purchaser against the transportation company at the
time the shipment is received.
Please record your equipment identification information below for future reference. This information can be
found on your machine nameplate.
Product _________________________________________________________________________________
Model Number ___________________________________________________________________________
Code Number or Date Code_________________________________________________________________
Serial Number____________________________________________________________________________
Date Purchased___________________________________________________________________________
Where Purchased_________________________________________________________________________
Whenever you request replacement parts or information on this equipment, always supply the information you
have recorded above. The code number is especially important when identifying the correct replacement parts.
On-Line Product Registration
- Register your machine with Lincoln Electric either via fax or over the Internet.
• For faxing: Complete the form on the back of the warranty statement included in the literature packet
accompanying this machine and fax the form per the instructions printed on it.
• For On-Line Registration: Go to our WEB SITE at www.lincolnelectric.com. Choose “Quick Links” and then
“Product Registration”. Please complete the form and submit your registration.
Read this Operators Manual completely before attempting to use this equipment. Save this manual and keep it
handy for quick reference. Pay particular attention to the safety instructions we have provided for your protection.
The level of seriousness to be applied to each is explained below:
WARNING
This statement appears where the information must be followed exactly to avoid serious personal injury or
loss of life.
CAUTION
This statement appears where the information must be followed to avoid minor personal injury or damage to
this equipment.
MASTER LOAD 750
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vii
TABLE OF CONTENTS
DESCRIPTION
TECHNICAL SPECIFICATIONS.........................................................................................1
SAFETY PRECAUTIONS...................................................................................................2
GENERAL DESCRIPTION .................................................................................................2
CONTROL UNIT.................................................................................................................2
ENCLOSURE......................................................................................................................2
INSTALLATION
BEFORE INSTALLATION...................................................................................................3
LOCATION..........................................................................................................................3
AIRFLOW CONSIDERATIONS ..........................................................................................3
POWER REQUIREMENTS ................................................................................................3
OPERATION
PURPOSE AND USE OF CONTROLS ..............................................................................4
LOAD BANK OPERATION .................................................................................................4
OPERATING INSTRUCTIONS...........................................................................................4
MAINTENANCE
ROUTINE AND PERIOD MAINTENANCE .........................................................................5
TROUBLESHOOTING
HOW TO USE TROUBLESHOOTING GUIDE ...................................................................6
TROUBLESHOOTING GUIDE ...........................................................................................7
DIAGRAMS
WIRING DIAGRAM...........................................................................................................10
DIMENSION PRINT..........................................................................................................11
PARTS ...............................................................................................................appendix
MASTER LOAD 750
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1
DESCRIPTION
1
TECHNICAL SPECIFICATIONS – MASTER LOAD 750
INPUT – POWER
120 VOLT, 15 A, 60 Hz , SINGLE PHASE
LOAD CAPABILITY
750 Amps @50V AC or DC (in incrementing fixed steps of 25, 25, 50, 50, 100, 250, 250)
PROTECTION FUSES
Control Circuit
15 amp
Voltmeters
3 amp
COOLING BLOWER
82 dBA at 3 ft
MAXIMUM COOLING AIR TEMPERATURE
120°F (50° C)
PHYSICAL DIMENSIONS
Height
34.75 in
883 mm
Width
24 in
Depth
28.5 in
724 mm
610 mm
MASTER LOAD 750
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2
DESCRIPTION
of all switched ON load steps.
SAFETY PRECAUTIONS
Before installation, read and observe all safe-
ty precautions throughout this manual.
4. LOAD STEPS switches - Connect and discon-
nect load steps. Values are shown above
each switch.
WARNING
5. Analog Meters - Monitors DC volts, DC amps,
AC volts, and AC amps applied to the load
bank.
ELECTRIC SHOCK can kill.
• Turn the input supply power
OFF at the disconnect switch or
fuse box before working on this
equipment.
ENCLOSURE
CAUTION
• Do not touch electrically hot
parts.
The outside dimensions of the Master Load 750 Load
Bank are listed on Technical Specifications page at
the beginning of this section of the manual. The Load
Bank is mounted on casters. One set of casters has
lockable wheels.
HOT EXHAUST can burn skin.
• Allow resistance elements to cool
before working near them.
Do not allow the Load Bank to be placed where hot
exhaust air can recirculate back through the unit caus-
ing a constant rise in cooling air temperature.
------------------------------------------------------------------------
ROTATING FAN can cause injury.
• Do not touch moving fan
components.
The Master Load 750 Load Bank contains a blower
(approximately 82dBA at 3 ft.) which provides the nec-
essary cooling air for the load elements. An exhaust
temperature sensor is provided to monitor the exhaust
temperature. This switch is electrically interlocked
with the load application circuit. If an unsafe tempera-
ture is detected in the exhaust of the Load Bank, the
BLOWER FAIL light comes on and the load is discon-
nected from the resistive elements.
------------------------------------------------------------------------
GENERAL DESCRIPTION
The Master Load 750 Load Bank is designed for elec-
trically loading and testing power sources. The unit is
designed for production line and job site use.
Air to cool the load elements enters the screened
intakes located on one end of the Load Bank. The air
passes over the resistive elements and is then dis-
charged through the screened opening at the other
end of the Load Bank.
The total loading capability of the Master Load 750 is
in fixed steps of 25, 25, 50, 50, 100, 250, 250 Amps
@ 50V AC or DC, totaling 750 Amps. Using the tog-
gle switches on the control panel, any combination of
the available load steps may be selected to achieve a
desired load.
The Load Bank also contains fuses for short circuit
protection. The control circuit is protected with a 15
amp fuse while the voltmeters are protected with 3
amp fuses.
CONTROL UNIT
The loads described above are controlled from an
integral control panel.
WARNING
Do not operate the Load Bank with any screen or
cover removed. This may expose the operator to
high voltage and rotating fan blades.
1. CONTROL POWER ON/OFF switch - Applies
power to the load bank and starts the blower.
The CONTROL POWER indicator lights when
power is applied.
---------------------------------------------------------------------
CAUTION
2. BLOWER FAIL indicator - Indicates an air fail-
ure condition or insufficient cooling airflow.
Do not exceed the voltage rating of load resistive cir-
cuit configuration.
------------------------------------------------------------------------
3. MASTER LOAD ON/OFF switch - Allows
instantaneous connection and disconnection
MASTER LOAD 750
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INSTALLATION
The over temperature switch, a protective device in
the load bank, will guard against some of these prob-
lems. If protective circuitry prevents application of the
load, determine the source of the problem. DO NOT
DISABLE THE OVER TEMPERATURE SWITCH.
This causes a safety hazard and voids our warranty.
The following installation instructions are critical to the
safe operation of the Load Bank. Refer to the Load
Bank Safety section of this manual.
BEFORE INSTALLATION
Inspect the Load Bank for obvious damage such as
broken wires, broken or dented panels, cracked
ceramic insulators, or any other component breakage
that may have occurred in shipment.
LOCATION
------------------------------------------------------------------------
The Master Load 750 is a portable, indoor, outdoor
Load Bank, and should be installed in a dry, cool,
well-ventilated area. Cool air must be continually
available and the hot exhaust air must be dissipated,
not recirculated through the unit. Install the Load
Bank so that the inlet and exhaust panels have unre-
stricted airflow clearance.
POWER REQUIREMENTS
The Load Bank requires a 120 volt, single phase, 60
Hz, 15 amp source of power for operation of the con-
trol panel and cooling fan. A power cord for control
power is provided with the Load Bank. Connect the
power cord to a grounded 120 volt source.
Load power is connected to the Load Bank through
receptacles on the side of the Load Bank labeled L1
and L2.
CAUTION
Installation must prevent hot exhaust air from recircu-
lating into the air intake. Inlet air temperatures
exceeding 120° F (50° C) may cause damage to the
Load Bank. After installation, test the unit at full load
and verify that the inlet air temperature does not
exceed 120° F (50° C).
WARNING
Do not energize the Load Bank with
the top cover removed. Make sure
the top cover panel is securely fas-
tened to the frame.
------------------------------------------------------------------------
AIRFLOW CONSIDERATIONS
Even with an ample supply of cooling air, the load bank
may overheat if it is not properly installed. There are
two types of airflow problems that should be avoided:
------------------------------------------------------------------------
Cables to the Load Bank should be of adequate size
to handle the maximum rated current according to the
1. Recirculating Airflow - If the hot, exhausted air
is permitted to recirculate through the load bank,
the air will reach such a high temperature and low
density that it will no longer cool the resistance
elements. A load bank should not be installed so
close to any surface as to reflect the exhausted air
back to the air intake. When two or more load
banks are being used, care must be taken in posi-
tioning the units so that the exhausted air of one
unit does not feed the air intake of another.
National Electrical Code and any local codes.
A
ground stud is provided and must be connected to the
frame of the power source, which in turn must be con-
nected to a good earth ground.
WARNING
Never exceed the rated voltage as this will cause the
Load Bank to overheat.
2. Restriction of Cooling Air - Any obstruction
located within 8 feet (2.4 m) of the inlet and
exhaust screens will restrict the load bank's air-
flow. Airflow is also restricted when two or more
load banks have air inlets positioned too close to
each other. This competition for cooling air caus-
es a low pressure area, restricting adequate air-
flow.
------------------------------------------------------------------------
Lower voltages and different frequencies may be
applied to the load circuit of the Load Bank.
Frequency change causes no derating of the load;
however, the applied KW with a lower voltage is com-
puted by using the following formula:
2
(Voltage Applied)
KW
= KW
X
Applied
Rated
WARNING
2
(Voltage Rated)
It is important to install the Load Bank properly.
Installation errors may result in a catastrophic failure.
MASTER LOAD 750
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OPERATION
PURPOSE AND USE OF CONTROLS OPERATING INSTRUCTIONS
1. POWER ON/OFF switch - Turns on cooling fan
and powers remainder of control circuit. Red light
shows POWER ON.
1. Connect Load Bank to 120 volts, single phase, 60
Hz power source.
2. Connect a wire from the Load Bank frame ground
stud to power source frame.
2. BLOWER FAIL indicator - The purpose of the
BLOWER FAIL lamp is to warn the operator and
remove the load to the load bank in case of an air
failure or improper cooling of the load elements.
3. Connect power source frame to a good earth
ground.
3. MASTER LOAD ON/OFF switch - The MASTER
LOAD switch connects power to all load steps,
thus allowing all load steps which are actuated to
load at the same time. It is also a master load
disconnect.
4. Connect appropriate power source leads to Load
Bank.
5. With POWER and MASTER LOAD switches in the
OFF position, start the generator.
4. LOAD STEPS switches - The load in amps is
marked above each actuating switch. A load step
may be turned ON or OFF before or during a test
but will load the unit only when the MASTER
LOAD switch is ON. NOTE: For DC loads, if the
polarity is not correct the load step switches will
not activate the load.
6. Place the POWER switch in the ON position.
The red POWER lamp will light.
7. Position the LOAD STEPS switches for the
desired load.
8. Turn on the MASTER LOAD switch to apply
desired load. Load steps may be added or delet-
ed at any time.
5. ANALOG METERS - Monitors load characteristics
DC and AC, Volts, and Amps.
9. Use analog meters to monitor applied load.
LOAD BANK OPERATION
10. After running tests, remove the load by turning off
the MASTER LOAD switch. Residual heat may
be removed from the Load Bank by allowing the
blower to run a few minutes after load is removed.
Although not required for maintaining Load Bank
integrity, this procedure may guard operating per-
sonnel from possible burn injuries.
All tests start with control panel switches in the OFF
position.
CAUTION
Before energizing any load, verify that load voltage
does not exceed rated voltage of load bank.
------------------------------------------------------------------------
WARNING
DO NOT touch the exhaust screen
during operation. The screen will
become hot from the exhausted heat
and may cause a serious burn.
Refer to the Load Bank Safety sec-
tion of this manual.
The unit is energized by turning the POWER switch
ON. This also energizes the cooling fan motor.
CAUTION
Do not attempt operation if fan is not running. Fan
inlet and exhaust must be unrestricted. The opera-
tion of the fan is vital to the safe operation of this Load
Bank. If BLOWER FAIL indicator light comes on and
stays on for more than a few seconds without the load
dropping out, shut off the POWER switch at once.
Remove all power to the unit and check for proper
operation of fan safety circuit. Failure to correct cool-
ing air loss condition will result in destruction of the
Load Bank. Refer to the Load Bank Safety section
of this manual.
DO NOT allow objects to enter or block screens.
------------------------------------------------------------------------
11. Place the POWER switch to the OFF position.
12. Shut down all power sources to the Load Bank.
13. Disconnect the power source cables to the Load
Bank.
------------------------------------------------------------------------
MASTER LOAD 750
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5
5
MAINTENANCE
4. Inspect for loose hardware or loose connections.
Tighten where required.
SAFETY PRECAUTIONS
Before servicing, read and observe all safety
precautions throughout this manual.
5. Inspect all connections for oxidation or corrosion.
Clean the connection or replace the hardware
where required.
WARNING
6. Inspect all magnetic contactors to make sure that
the contacts are not severely pitted or corroded.
The contacts must move freely and be properly
seated.
ELECTRIC SHOCK can kill.
• Only qualified personnel should
perform this maintenance.
7. Clean all dirt and debris out of the load bank.
This can be accomplished by blowing the inside of
the unit with clean, dry compressed air (not to
exceed 40 PSI). Eye protection should be worn
when cleaning the Load Bank with compressed
air.
• Turn the input supply power
OFF at the disconnect switch or
fuse box before working on this
equipment.
• Do not touch electrically hot
parts.
8. Inspect all the wiring for any sign of insulation fail-
ure.
• Allow resistance elements to
cool before working near them.
9. Replace all access panels and screens. Tighten
all the fastening hardware securely.
• Do not touch moving fan
components.
------------------------------------------------------------------------
10. Check the indicator lamps on the control panel.
ROUTINE AND PERIOD
MAINTENANCE
ANNUALLY
DAILY
The blower motor should be lubricated according to
the motor manufacturers' requirements and specifica-
tions on the motor nameplate.
1. Remove any restrictions to airflow through the
Load Bank.
2. Check the screens to make sure that no objects
have blocked or entered the openings.
3. Verify that the airflow is in the proper direction.
4. Assure that there is no recirculation of the exhaust
air through the Load Bank.
THREE MONTHS OR 500 HOURS
1. Remove access panels and screens.
2. Inspect the load resistors for mechanical break-
down which is demonstrated by excessive sag-
ging of the elements. Replace with new resistor
elements as required.
3. Inspect for broken ceramic insulators. Replace
with a new ceramic insulator if any cracks are
found.
MASTER LOAD 750
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6
6
TROUBLESHOOTING & REPAIR
HOW TO USE TROUBLESHOOTING GUIDE
WARNING
This Troubleshooting Guide is designed to be used by qualified service personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
and machine operator and will invalidate your factory warranty. For your safety, please
observe all safety notes and precautions detailed in the Safety Sections of this manual to
avoid electrical shock or danger while troubleshooting this equipment.
This Troubleshooting Guide is provided to
help you locate and repair possible
problems.
Step 3.
If you have exhausted all of the
recommended checks in step 2, contact the
Lincoln
Electric
Customer
Service
Step 1. LOCATE PROBLEM (SYMPTOM)
Look under the column labeled “PROBLEM
(SYMPTOMS)”. This column describes
possible symptoms that your unit may
exhibit. Find the listing that best describes
the symptom that your machine is exhibiting.
Department.
Step 2. Check Possible Causes
The second column labeled “POSSIBLE
CAUSES/REMEDIES”
lists
typical
possibilities that may contribute to the
machine symptom. Perform these checks
and remedies in the order listed.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the
Lincoln Electric Service Department for technical troubleshooting assistance before you proceed. Call 216-383-2531 or
1-800-833-9353.
MASTER LOAD 750
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7
7
TROUBLESHOOTING & REPAIR
Observe all Safety Guidelines detailed throughout this manual
PROBLEMS
(SYMPTOMS)
POSSIBLE CAUSES/REMEDIES
1. Load bank main power fails to
come on.
a. Main switch or circuit breaker is not closed.
b. Unit is not connected according to the Schematic/Interconnection dia-
gram.
c. Terminals may be damaged.
1.
d. Fuses may be blown. (Check and replace as required.)
e. Fuse may be blown in load bank control circuit. (Check and replace as
1.
required.)
f. Dirty or loose connection at main power switch.
2. Blower motor does not operate.
a. Main switch or circuit breaker may not be closed.
b. Power may not be connected to load bank blower circuit.
c. External power supply may be inadequate.
1.
d. Control Circuit fuse may be blown. (Check and replace as required.)
e. Main power switch may be faulty.
f. Check for loose or broken connections.
1.
When checking fuses for continuity, be sure to remove all fuses from clips (in fuse block or disconnect switch).
Test each fuse individually, out of circuit.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353.
MASTER LOAD 750
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8
8
TROUBLESHOOTING & REPAIR
Observe all Safety Guidelines detailed throughout this manual
PROBLEMS
(SYMPTOMS)
POSSIBLE CAUSES/REMEDIES
3. BLOWER OVER TEMPERATURE a. Airflow restrictions present at load bank intake or exhaust.
indicator lights are on, but the
blower is operating.
b. Maximum rating of the load bank may have been exceeded.
4. Fan blade is broken or not turning. a. Fan blade motion may be obstructed.
b. Fan blade may be loose at hub or is not keyed properly.
5. Load step(s) cannot be energized. a. Check to see if over temperature indicator is lit. (See problem 3.)
b. A blower failure may exist. (See problem 2.)
c. Master load switch may be faulty.
d. Control power may be inadequate.
e.
Fuse may be blown in load bank control circuit. (Check and replace as
1.
required).
f. Load step switch may be faulty.
g. Load step contactor may be inoperative.
h. Load step resistor may be open.
i. Output polarity connection is incorrect. Verify correct polarity connection
to the load bank.
1.
When checking fuses for continuity, be sure to remove all fuses from clips (in fuse block or disconnect switch).
Test each fuse individually, out of circuit.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353.
MASTER LOAD 750
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9
9
TROUBLESHOOTING & REPAIR
Observe all Safety Guidelines detailed throughout this manual
PROBLEMS
(SYMPTOMS)
POSSIBLE CAUSES/REMEDIES
6. Contactor “chattering” exists.
a. Contacts and/or core may be dirty.
b. Check for loose or faulty connections to the contactor coil.
c. Control circuit line voltage may be too low.
7. Load bank or load step does not a. Applied load voltage may be either derated or inadequate.
give rated load.
b. Contactor may not be closing properly.
c. Load step resistor element may be open.
1.
When checking fuses for continuity, be sure to remove all fuses from clips (in fuse block or disconnect switch).
Test each fuse individually, out of circuit.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353.
MASTER LOAD 750
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10
10
DIAGRAMS
MASTER LOAD 750
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11
11
DIAGRAMS
MASTER LOAD 750
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PARTS
MASTER LOAD 750
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# Indicates a change this printing.
* Recommended Spare Part
ITEM DESCRIPTION
Use only the parts marked “x” in the column under the
heading number called for in the model index page.
PART NO.
QTY. 1 2 3 4 5 6 7 8 9
1
2
3
4
5
6
7
8
9
Base, Load Bank
Side Panel, (Left)
Side Panel, (Right)
Venturi, Fan
Rail (For Relay K8 Mtg.)
Pan, Relay
Panel, Screened
Cover. Load Bank
Cover. Res Element
M18720
1
1
1
1
1
1
2
1
2
1
1
6
3
12
21
28
1
1
1
2
1
1
1
1
1
1
4
1
1
2
2
1
1
1
2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
M18720-1
M18720-2
M18720-3
M18720-62
M18720-5
M18720-6
M18720-7
M18720-8
M18720-9
M18720-10
M18720-11
M18720-12
M18720-13
M18720-14
M18720-15
M18720-16
M18720-61
M18720-58
M18720-59
M18720-60
M18720-21
M18720-22
M18720-23
M18720-24
M18720-25
M18720-26
M18720-27
M18720-28
S16656-4
10 Terminal Board {RB}
11 Terminal Board {RA}
12 Resistance Element
13 Resistance Element
14 Resistence Element
15 Rod, Element Support
16 Bus Link
17 Plate Identification
18 Relay (K8)
19 Label Warning
20 Label Warning
21 Label Warning
22 Plate, Designation (L1,L2,+,-)
23 Plate, Designation (GND)
24 Line Cord {P1}
25 Control Panel
26 Schematic/Wiring Diagram
27 Relay {K1-K4}
28 Relay {K5}
29 Support, Motor
30 Terminal Connector {W1, W2}
31 Relay {K6, K7}
32 Fuseholder {XF1 - XF3}
33 Fuse, 15A {F1}
34 Motor, 1/4 HP, 120V {B1}
35 Fuse, 3A {F2.F3}
36 - -
M18720-29
M18720-30
M18720-31
M9983-4
M18720-32
37 Caster, Swivel
38 Impeller, Fan
39 Tube, Steatite
40 Molding
41 Transformer, Current {CT1}
42 Bus Bar
M18720-34
M18720-35
M18720-36
M18720-37
M18720-38
M18720-39
2
1
X
X
210 X
AR X
1
1
X
X
43 - -
44 Caster, Rigid
45 Pin, Spring Clip
46 Grommet
47 Cover
48 Nut, Jam
M18720-41
M18720-42
M18720-43
M18720-63
M18720-64
2
42
1
1
1
X
X
X
X
X
3-18-97
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# Indicates a change this printing.
* Recommended Spare Part
ITEM DESCRIPTION
Use only the parts marked “x” in the column under the
heading number called for in the model index page.
PART NO.
QTY. 1 2 3 4 5 6 7 8 9
49 Bushing, Seal
50 Spring
51 Switch, Temp {S11}
52 - -
M18720-44
M18720-45
M18720-46
1
42
1
X
X
X
53 Nut Assembled Washer
54 Threadlocker
55 Stud
M18720-47
M18720-48
M18720-49
84
AR X
4
X
X
56 - -
57 - -
58 Semiconductor, Rectifier {CR1}
59 - -
60 Shunt, 800A. 50MV {R10}
61 Wire, Electrical 2 AWG
62 - -
M18720-52
1
1
X
X
M18720-53
M18720-54
75ft. X
63 Nut #1/2 - 13
64 Washer, Flat, 1/2
65 - -
M18720-56
M18720-57
4
1
X
X
3-18-97
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NOTES
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NOTES
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NOTES
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● Do not touch electrically live parts or
electrode with skin or wet clothing.
● Insulate yourself from work and
ground.
● Keep flammable materials away.
● Wear eye, ear and body protection.
WARNING
Spanish
● No toque las partes o los electrodos ● Mantenga el material combustible
● Protéjase los ojos, los oídos y el
bajo carga con la piel o ropa moja-
da.
● Aislese del trabajo y de la tierra.
fuera del área de trabajo.
cuerpo.
AVISO DE
PRECAUCION
French
● Ne laissez ni la peau ni des vête-
ments mouillés entrer en contact
avec des pièces sous tension.
● Gardez à l’écart de tout matériel
inflammable.
● Protégez vos yeux, vos oreilles et
votre corps.
ATTENTION
● Isolez-vous du travail et de la terre.
German
● Berühren Sie keine stromführenden
Teile oder Elektroden mit Ihrem
Körper oder feuchter Kleidung!
● Isolieren Sie sich von den
● Entfernen Sie brennbarres Material! ● Tragen Sie Augen-, Ohren- und Kör-
perschutz!
WARNUNG
Elektroden und dem Erdboden!
Portuguese
● Não toque partes elétricas e elec-
trodos com a pele ou roupa molha-
da.
● Mantenha inflamáveis bem guarda- ● Use proteção para a vista, ouvido e
dos.
corpo.
ATENÇÃO
● Isole-se da peça e terra.
Japanese
Chinese
Korean
Arabic
READ AND UNDERSTAND THE MANUFACTURER’S INSTRUCTION FOR THIS EQUIPMENT AND THE CONSUMABLES TO BE
USED AND FOLLOW YOUR EMPLOYER’S SAFETY PRACTICES.
SE RECOMIENDA LEER Y ENTENDER LAS INSTRUCCIONES DEL FABRICANTE PARA EL USO DE ESTE EQUIPO Y LOS
CONSUMIBLES QUE VA A UTILIZAR, SIGA LAS MEDIDAS DE SEGURIDAD DE SU SUPERVISOR.
LISEZ ET COMPRENEZ LES INSTRUCTIONS DU FABRICANT EN CE QUI REGARDE CET EQUIPMENT ET LES PRODUITS A
ETRE EMPLOYES ET SUIVEZ LES PROCEDURES DE SECURITE DE VOTRE EMPLOYEUR.
LESEN SIE UND BEFOLGEN SIE DIE BETRIEBSANLEITUNG DER ANLAGE UND DEN ELEKTRODENEINSATZ DES HER-
STELLERS. DIE UNFALLVERHÜTUNGSVORSCHRIFTEN DES ARBEITGEBERS SIND EBENFALLS ZU BEACHTEN.
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● Keep your head out of fumes.
● Use ventilation or exhaust to
remove fumes from breathing zone.
● Turn power off before servicing.
● Do not operate with panel open or
guards off.
WARNING
Spanish
● Los humos fuera de la zona de res-
piración.
● Mantenga la cabeza fuera de los
humos. Utilice ventilación o
aspiración para gases.
● Desconectar el cable de ali-
mentación de poder de la máquina
antes de iniciar cualquier servicio.
● No operar con panel abierto o
guardas quitadas.
AVISO DE
PRECAUCION
French
● Débranchez le courant avant l’entre- ● N’opérez pas avec les panneaux
tien.
● Gardez la tête à l’écart des fumées.
● Utilisez un ventilateur ou un aspira-
teur pour ôter les fumées des zones
de travail.
ouverts ou avec les dispositifs de
protection enlevés.
ATTENTION
German
● Strom vor Wartungsarbeiten
abschalten! (Netzstrom völlig öff-
nen; Maschine anhalten!)
● Anlage nie ohne Schutzgehäuse
oder Innenschutzverkleidung in
Betrieb setzen!
● Vermeiden Sie das Einatmen von
Schweibrauch!
● Sorgen Sie für gute Be- und
Entlüftung des Arbeitsplatzes!
WARNUNG
Portuguese
● Não opere com as tampas removidas.
● Desligue a corrente antes de fazer
serviço.
● Mantenha-se afastado das partes
moventes.
● Não opere com os paineis abertos
ou guardas removidas.
● Mantenha seu rosto da fumaça.
● Use ventilação e exhaustão para
remover fumo da zona respiratória.
ATENÇÃO
● Não toque as partes elétricas nuas.
Japanese
Chinese
Korean
Arabic
LEIA E COMPREENDA AS INSTRUÇÕES DO FABRICANTE PARA ESTE EQUIPAMENTO E AS PARTES DE USO, E SIGA AS
PRÁTICAS DE SEGURANÇA DO EMPREGADOR.
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• World's Leader in Welding and Cutting Products •
• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com
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