MQ Power DCA125USI Guide

THIS MANUAL MUST ACCOMPANY THE EQUIPMENT AT ALL TIMES.
To find the latest revision of this
publication, visit our website at:
www.multiquip.com
®
MODEL DCA125USI
60 HZ GENERATOR
(ISUZU 4HK1X DIESEL ENGINE)
Revision #1 (03/25/11)
OPERATION AND PARTS MANUAL

PAGE 2 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
PROPOSITION 65 WARNING
Diesel engine exhaust and some of

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 3
If you believe that your vehicle has a defect that could cause a crash or could
cause injury or death, you should immediately inform the National Highway
Traffic Safety Administration (NHTSA) in addition to notifying Multiquip at
1-800-421-1244.
If NHTSA receives similar complaints, it may open an investigation, and if it
finds that a safety defect exists in a group of vehicles, it may order a recall and
remedy campaign. However, NHTSA cannot become involved in individual
problems between you, your dealer, or Multiquip.
To contact NHTSA, you may either call the Vehicle Safety Hotline toll-free at
1-888-327-4236 (TTY: 1-800-424-9153), go to http://www.nhtsa.dot.gov; or
write to:
Administrator
NHTSA
1200 New Jersey Avenue S.E.
Washington, DC 20590
You can also obtain information about motor vehicle safety from
http://www.safecar.gov.
REPORTING SAFETY DEFECTS

PAGE 4 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
TABLE OF CONTENTS
DCA125USI 60 Hz Generator
Proposition 65 Warning ........................................... 2
Reporting Safety Defects......................................... 3
Table Of Contents.................................................... 4
Parts Ordering Procedures...................................... 5
Safety Information .............................................. 6-11
Specifications ........................................................ 12
Dimensions............................................................ 13
Installation ............................................................. 14
Installation ............................................................. 15
General Information............................................... 16
Major Components ................................................ 17
Generator Control Panel........................................ 18
Engine Operating Panel.................................... 20-21
Output Terminal Panel Familiarization .............. 22-24
Load Application .................................................... 25
Generator Outputs................................................. 26
Generator Outputs/Gauge Reading....................... 27
Output Terminal Panel Connections ................. 28-29
Inspection/Setup............................................... 30-33
Generator Start-Up Procedure ........................ 34-35
Generator Shut-Down Procedures ........................ 36
Maintenance..................................................... 37-40
Trailer Maintenance .......................................... 41-44
Trailer WirIng Diagram ........................................... 45
Generator Wiring Diagram..................................... 46
Engine Wiring Diagram.......................................... 47
Controller Wiring Diagram ..................................... 48
Troubleshooting (Generator).................................. 49
Troubleshooting (Diagnostic Lamp) ....................... 50
Explanation Of Code In Remarks Column............. 52
Suggested Spare Parts ......................................... 53
Component Drawings
Generator Assembly......................................... 54-55
Control Box Assembly ...................................... 56-59
Engine and Radiator Assembly ........................ 60-65
Output Terminal Assembly................................ 66-66
Battery Assembly.............................................. 68-69
Muffler Assembly .............................................. 70-71
Fuel Tank Assembly ......................................... 72-73
Enclosure Part 1 Assembly .............................. 74-77
Enclosure Part 2 Assembly .............................. 78-81
Rubber Seals Assembly ................................... 82-83
Nameplate and Decals Assembly .................... 84-87
Terms And Conditions Of Sale — Parts ................ 88

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 5
PARTS ORDERING PROCEDURES
www.multiquip.com
Ordering parts has never been easier!
Choose from three easy options:
WE ACCEPT ALL MAJOR CREDIT CARDS!
When ordering parts, please supply:
❒Dealer Account Number
❒Dealer Name and Address
❒Shipping Address (if different than billing address)
❒Return Fax Number
❒Applicable Model Number
❒Quantity, Part Number and Description of Each Part
❒Specify Preferred Method of Shipment:
✓ UPS/Fed Ex ✓DHL
■Priority One ✓Tr u c k
■Ground
■Next Day
■Second/Third Day
If you have an MQ Account, to obtain a Username
and Password, E-mail us at: parts@multiquip.
com.
To obtain an MQ Account, contact you
r
District Sales Manager for more information.
Order via Internet (Dealers Only):
Order parts on-line using Multiquip’s SmartEquip website!
■View Parts Diagrams
■Order Parts
■Print Specification Information
Note: Discounts Are Subject To Change
Goto www.multiquip.com and click on
Order Parts to log in and save!
Use the internet and qualify for a 5% Discount
on Standard orders for all orders which include
complete part numbers.*
Order via Fax (Dealers Only):
All customers are welcome to order parts via Fax.
Domestic (US) Customers dial:
1-800-6-PARTS-7 (800-672-7877)
Fax your order in and qualify for a 2% Discount
on Standard orders for all orders which include
complete part numbers.*
Order via Phone: Domestic (US) Dealers Call:
1-800-427-1244
Best Deal!
International Customers should contact
their local Multiquip Representatives for
Parts Ordering information.
Non-Dealer Customers:
Contact your local Multiquip Dealer for
parts or call 800-427-1244 for help in
locating a dealer near you.
Note: Discounts Are Subject To Change
Effective:
January 1st, 2006
NOTICE
All orders are treated as Standard Orders and will
ship the same day if received prior to 3PM PST.

PAGE 6 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
SAFETY INFORMATION
Do not operate or service the equipment before reading the
entire manual. Safety precautions should be followed at all
times when operating this equipment. Failure to read and
understand the safety messages and operating instructions
could result in injury to yourself and others.
SAFETY MESSAGES
The four safety messages shown below will inform you
about potential hazards that could injure you or others.The
safety messages specifically address the level of exposure
to the operator and are preceded by one of four words:
DANGER, WARNING, CAUTION or NOTICE.
SAFETY SYMBOLS
DANGER
Indicates a hazardous situation which, if not avoided,
WILL result in DEATH or SERIOUS INJURY.
WARNING
Indicates a hazardous situation which, if not avoided,
COULD result in DEATH or SERIOUS INJURY.
CAUTION
Indicates a hazardous situation which, if not avoided,
COULD result in MINOR or MODERATE INJURY.
NOTICE
Addresses practices not related to personal injury.
Potential hazards associated with the operation of this
equipment will be referenced with hazard symbols which
may appear throughout this manual in conjunction with
safety messages.

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 7
SAFETY INFORMATION
GENERAL SAFETY
CAUTION
NEVER operate this equipment without proper protective
clothing, shatterproof glasses, respiratory protection,
hearing protection, steel-toed boots and other protective
devices required by the job or city and state regulations.
NEVER operate this equipment when not
feeling well due to fatigue, illness or when
under medication.
NEVER operate this equipment under the influence of
drugs or alcohol.
ALWAYS check the equipment for loosened threads or
bolts before starting.
DO NOT use the equipment for any purpose other than
its intended purposes or applications.
NOTICE
This equipment should only be operated by trained and
qualified personnel 18 years of age and older.
Whenever necessary, replace nameplate, operation and
safety decals when they become difficult read.
Manufacturer does not assume responsibility for any
accident due to equipment modifications. Unauthorized
equipment modification will void all warranties.
NEVER use accessories or attachments that are not
recommended by MQ Power for this equipment. Damage
to the equipment and/or injury to user may result.
ALWAYS know the location of the nearest
fire extinguisher.
ALWAYS know the location of the nearest
first aid kit.
ALWAYS know the location of the nearest
phone or keep a phone on the job site. Also, know the
phone numbers of the nearest ambulance, doctor and
fire department. This information will be invaluable in
the case of an emergency.
GENERATOR SAFETY
DANGER
NEVER operate the equipment in an explosive
atmosphere or near combustible materials.An
explosion or fire could result causing severe
bodily harm or even death.
WARNING
NEVER disconnect any emergency or safety devices.
These devices are intended for operator safety.
Disconnection of these devices can cause severe injury,
bodily harm or even death.Disconnection of any of these
devices will void all warranties.
CAUTION
NEVER lubricate components or attempt service on a
running machine.
NOTICE
ALWAYS ensure generator is on level ground before use.
ALWAYS keep the machine in proper running condition.
Fix damage to machine and replace any broken parts
immediately.
ALWAYS store equipment properly when it is not being
used. Equipment should be stored in a clean, dry location
out of the reach of children and unauthorized personnel

PAGE 8 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
SAFETY INFORMATION
ENGINE SAFETY
DANGER
The engine fuel exhaust gases contain poisonous carbon
monoxide. This gas is colorless and odorless, and can
cause death if inhaled.
The engine of this equipment
requires an adequate free
flow of cooling air. NEVER
operate this equipment in
any enclosed or narrow area
where free flow of the air is
restricted. If the air flow is
restricted it will cause injury to people and property and
serious damage to the equipment or engine.
WARNING
DO NOT place hands or fingers inside engine
compartment when engine is running.
NEVER operate the engine with heat shields or
guards removed.
Keep fingers, hands hair and clothing away
from all moving parts to prevent injury.
DO NOT remove the radiator cap while the
engine is hot. High pressure boiling water
will gush out of the radiator and severely
scald any persons in the general area of
the generator.
DO NOT remove the coolant drain plug while the engine
is hot. Hot coolant will gush out of the coolant tank and
severely scald any persons in the general area of the
generator.
DO NOT remove the engine oil drain plug while the
engine is hot. Hot oil will gush out of the oil tank and
severely scald any persons in the general area of the
generator.
CAUTION
NEVER touch the hot exhaust manifold,
muffler or cylinder. Allow these parts to cool
before servicing equipment.
NOTICE
NEVER run engine without an air filter or with a dirty air
filter. Severe engine damage may occur. Service air filter
frequently to prevent engine malfunction.
NEVER tamper with the factory settings
of the engine or engine governor. Damage
to the engine or equipment can result
if operating in speed ranges above the
maximum allowable.
Wet stacking is a common problem with diesel engines
which are operated for extended periods with light or
no load applied. When a diesel engine operates without
sufficient load (less than 40% of the rated output), it will
not operate at its optimum temperature. This will allow
unburned fuel to accumulate in the exhaust system,
which can foul the fuel injectors, engine valves and
exhaust system, including turbochargers, and reduce
the operating performance.
In order for a diesel engine to operate at peak efficiency,
it must be able to provide fuel and air in the proper ratio
and at a high enough engine temperature for the engine
to completely burn all of the fuel.
Wet stacking does not usually cause any permanent
damage and can be alleviated if additional load is
applied to relieve the condition. It can reduce the system
performance and increase maintenance. Applying an
increasing load over a period of time until the excess
fuel is burned off and the system capacity is reached
usually can repair the condition. This can take several
hours to burn off the accumulated unburned fuel.
State Health Safety Codes and Public Resources
Codes specify that in certain locations, spark arresters
must be used on internal combustion engines that use
hydrocarbon fuels. A spark arrester is a device designed
to prevent accidental discharge of sparks or flames
from the engine exhaust. Spark arresters are qualified
and rated by the United States Forest Service for this
purpose. In order to comply with local laws regarding
spark arresters, consult the engine distributor or the
local Health and Safety Administrator.

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 9
SAFETY INFORMATION
FUEL SAFETY
DANGER
DO NOT start the engine near spilled fuel or combustible
fluids. Diesel fuel is extremely flammable and its vapors
can cause an explosion if ignited.
ALWAYS refuel in a well-ventilated area, away from
sparks and open flames.
ALWAYS use extreme caution when working with
flammable liquids.
DO NOT fill the fuel tank while the engine is running
or hot.
DO NOT overfill tank, since spilled fuel could ignite if it
comes into contact with hot engine parts or sparks from
the ignition system.
Store fuel in appropriate containers, in well-ventilated
areas and away from sparks and flames.
NEVER use fuel as a cleaning agent.
DO NOT smoke around or near the
equipment. Fire or explosion could result
from fuel vapors or if fuel is spilled on a
hot engine.
TOWING SAFETY
CAUTION
Check with your local county or state safety
towing regulations, in addition to meeting
Department of Transportation (DOT)
SafetyTowing Regulations, before towing
your generator.
Refer to MQ Power trailer manual for additional safety
information.
In order to reduce the possibility of an accident while
transporting the generator on public roads, ALWAYS
make sure the trailer that supports the generator and
the towing vehicle are mechanically sound and in good
operating condition.
ALWAYS shutdown engine before transporting
Make sure the hitch and coupling of the towing vehicle
are rated equal to, or greater than the trailer “gross
vehicle weight rating.”
ALWAYS inspect the hitch and coupling for wear. NEVER
tow a trailer with defective hitches, couplings, chains, etc.
Check the tire air pressure on both towing vehicle and
trailer. Trailer tires should be inflated to 50 psi cold.
Also check the tire tread wear on both vehicles.
ALWAYS make sure the trailer is equipped with a safety
chain.
ALWAYS properly attach trailer’s safety chains to towing
vehicle.
ALWAYS make sure the vehicle and trailer directional,
backup, brake and trailer lights are connected and
working properly.
DOT Requirements include the following:
• Connect and test electric brake operation.
• Secure portable power cables in cable tray with tie
wraps.
The maximum speed for highway towing is 55 MPH unless
posted otherwise.Recommended off-road towing is not to
exceed 15 MPH or less depending on type of terrain.
Avoid sudden stops and starts.This can cause skidding,
or jack-knifing. Smooth, gradual starts and stops will
improve towing.
Avoid sharp turns to prevent rolling.
Trailer should be adjusted to a level position at all times
when towing.
Raise and lock trailer wheel stand in up position when
towing.
Place chock blocks underneath wheel to prevent rolling
while parked.
Place support blocks underneath the trailer’s bumper
to prevent tipping while parked.
Use the trailer’s swivel jack to adjust the trailer height to
a level position while parked.

PAGE 10 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
SAFETY INFORMATION
ELECTRICAL SAFETY
DANGER
DO NOT touch output terminals during
operation. Contact with output terminals
during operation can cause electrocution,
electrical shock or burn.
The electrical voltage required to
operate the generator can cause severe
injury or even death through physical contact with live
circuits. Turn generator and all circuit breakers OFF
before performing maintenance on the generator or
making contact with output terminals.
NEVER insert any objects into the output
receptacles during operation. This is
extremely dangerous.The possibility exists
of electrical shock, electrocution or
death.
Backfeed to a utility system can cause
electrocution and/or property damage.
NEVER connect the generator to a
building’s electrical system without
a transfer switch or other approved
device. All installations should be
performed by a licensed electrician in accordance with
all applicable laws and electrical codes. Failure to do so
could result in electrical shock or burn, causing serious
injury or even death.
Power Cord/Cable Safety
DANGER
NEVER let power cords or cables lay in water.
NEVER stand in water while AC power from the
generator is being transferred to a load.
NEVER use damaged or worn cables or cords when
connecting equipment to generator. Inspect for cuts in
the insulation.
NEVER grab or touch a live power
cord or cable with wet hands. The
possibility exists of electrical shock,
electrocution or death.
Make sure power cables are securely connected to the
generator’s output receptacles. Incorrect connections
may cause electrical shock and damage to the
generator.
NOTICE
ALWAYS make certain that proper power or extension
cord has been selected for the job. See Cable Selection
Chart in this manual.
Grounding Safety
DANGER
ALWAYS make sure that electrical circuits are properly
grounded to a suitable earth ground (ground rod) per
the National Electrical Code (NEC) and local codes
before operating generator. Severe injury or death by
electrocution can result from operating an ungrounded
generator.
NEVER use gas piping as an electrical ground.

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 11
SAFETY INFORMATION
BATTERY SAFETY
DANGER
DO NOT drop the battery. There is a possibility that the
battery will explode.
DO NOT expose the battery to open flames,
sparks, cigarettes, etc.The battery contains
combustible gases and liquids. If these
gases and liquids come into contact with a
flame or spark, an explosion could occur.
WARNING
ALWAYS wear safety glasses when handling
the battery to avoid eye irritation.The battery
contains acids that can cause injury to the
eyes and skin.
Use well-insulated gloves when picking up the battery.
ALWAYS keep the battery charged. If the battery is not
charged, combustible gas will build up.
ALWAYS recharge the battery in a well-ventilated
environment to avoid the risk of a dangerous concentration
of combustible gasses.
If the battery liquid (dilute sulfuric acid) comes into
contact with clothing or skin, rinse skin or clothing
immediately with plenty of water.
If the battery liquid (dilute sulfuric acid) comes into
contact with eyes, rinse eyes immediately with plenty
of water and contact the nearest doctor or hospital to
seek medical attention.
CAUTION
ALWAYS disconnect the NEGATIVE battery terminal
before performing service on the generator.
ALWAYS keep battery cables in good working condition.
Repair or replace all worn cables.
ENVIRONMENTAL SAFETY
NOTICE
Dispose of hazardous waste properly.
Examples of potentially hazardous waste
are used motor oil, fuel and fuel filters.
DO NOT use food or plastic containers to
dispose of hazardous waste.
DO NOT pour waste, oil or fuel directly onto the ground,
down a drain or into any water source.

PAGE 12 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
SPECIFICATIONS
Table 1. Generator Specifications
Model DCA125USI
Type Revolving field, self ventilated,
open protected type synchronous generator
Armature Connection Star with Neutral Zigzag
Phase 31
Standby Output 110 kW (137.5 kVA) 79 kW
Prime Output 100 kW (100 kVA) 72 kW
3Ø Voltage (L-L/L-N)
Voltage Selector Switch at 3Ø 240/139
208Y/120, 220Y/127,
240Y/139 N/A
3Ø Voltage (L-L/L-N)
Voltage Selector Switch at 3Ø 480/277
416Y/240, 440Y/254,
480Y/277 N/A
1Ø Voltage (L-L/L-N)
Voltage Selector Switch at 1Ø 240/120 N/A 240/120
Power Factor 0.8 1.0
Frequency 60 Hz
Speed 1800 rpm
Aux. AC Power Single Phase, 60 Hz
Aux. Voltage/Output 120V/4.8 Kw (2.4 kW x 2)
Sound Level dB (A)
Full Load at 23 ft. (7.0 Meters) 65
Dry Weight 5,689 lbs. (2,580 kg)
Wet Weight 7,012 lbs. (3,180 kg)
Table 2. Engine Specifications
Model ISUZU 4HK1XYGD-03 Tier 3
Type 4 cycle, water-cooled, direct injection, turbocharged,
air to air intercooled
No. of Cylinders 4 cylinders
Bore x Stroke 4.53 in. x 4.92 in. (115 mm x 125 mm)
Displacement 317 cu. in. (5193 cc)
Rated Output 152 HP/1800 RPM
Starting Electric
Coolant Capacity 5.2 gal. (19.7 liters)
Lube Oil Capacity 6.1 gal. (23.4 liters)
Fuel Type #2 Diesel Fuel
Fuel Leak Warning Capacity 42.3gal. (160 liters)
Fuel Tank Capacity 169 gal. (640 liters)
Fuel Consumption
7.3 gal. (27.6 L)/hr at full
load
5.7 gal. (21.7 L)/hr at 3/4
load
4.0 gal. (15.1 L)/hr at 1/2
load
2.4 gal. (9.1 L)/hr at 1/4
load
Battery 12V-128 Ah x 1

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 13
DIMENSIONS
Figure 1. Dimensions
Table 3. Dimensions
Reference
Letter Dimension in. (mm) Reference Letter Dimension in. (mm)
A 38.20 in. (970 mm.) F 120.10 in. (3,050 mm.)
B 37.00 in. (940 mm.) G 73.00 in. (1,855 mm.)
C 36.20 in. (920 mm.) H 48.80 in. (1,200 mm.)
D 37.00 in. (940 mm.)
E 3620 in. (920 mm.)

PAGE 14 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
INSTALLATION
Figure 2. Typical Generator Grounding Application

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 15
INSTALLATION
OUTDOOR INSTALLATION
Install the generator in a area that is free of debris,
bystanders, and overhead obstructions. Make sure the
generator is on secure level ground so that it cannot slide
or shift around. Also install the generator in a manner so
that the exhaust will not be discharged in the direction of
nearby homes.
The installation site must be relatively free from moisture
and dust. All electrical equipment should be protected from
excessive moisture. Failure to do will result in deterioration
of the insulation and will result in short circuits and
grounding.
Foreign materials such as dust, sand, lint and abrasive
materials have a tendency to cause excessive wear to
engine and alternator parts.
INDOOR INSTALLATION
Exhaust gases from diesel engines are extremely
poisonous. Whenever an engine is installed indoors the
exhaust fumes must be vented to the outside. The engine
should be installed at least two feet from any outside wall.
Using an exhaust pipe which is too long or too small can
cause excessive back pressure which will cause the engine
to heat excessively and possibly burn the valves.
MOUNTING
The generator must be mounted on a solid foundation (such
as concrete) and set firmly on the foundation to isolate
vibration of the generator when it is running.The generator
must set at least 6 inches above the floor or grade level (in
accordance to NFPA 110, Chapter 5-4.1). DO NOT remove
the metal skids on the bottom of the generator. They are
to resist damage to the bottom of the generator and to
maintain alignment.
CAUTION
Pay close attention to ventilation when operating the
generator inside tunnels and caves.The engine exhaust
contains noxious elements. Engine exhaust must be
routed to a ventilated area.
GENERATOR GROUNDING
To guard against electrical shock and possible damage to
the equipment, it is important to provide a good EARTH
ground.
Article 250 (Grounding) of the National Electrical Code
(NEC) provides guide lines for proper grounding and
specifies that the cable ground shall be connected to the
grounding system of the building as close to the point of
cable entry as practical.
NEC articles 250-64(b) and 250-66 set the following
grounding requirements:
1. Use one of the following wire types to connect the
generator to earth ground.
a. Copper - 10 AWG (5.3 mm2)
b. Aluminum - 8 AWG (8.4 mm2)
2. When grounding the generator (Figure 2) connect the
ground cable between the lock washer and the nut on
the generator and tighten the nut fully. Connect the
other end of the ground cable to earth ground.
3. NEC article 250-52(c) specifies that the earth ground rod
should be buried a minimum of 8 ft. into the ground.
NOTICE
When connecting the generator to any buildings
electrical system ALWAYS consult with a licensed
electrician.

PAGE 16 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
GENERATOR
This MQ Power Model generator (Figure 3) is a high quality
portable (requires a trailer for transport) power source for
telecom sites, lighting facilities, power tools, submersible
pumps and other industrial and construction machinery.
ENGINE OPERATING PANEL
The “Engine Operating Panel” is provided with the following:
Tachometer
Water Temperature Gauge
Warning Lamp
Pre-Heat Lamp
Oil Pressure Gauge
Charging Ammeter Gauge
Fuel Level Gauge
Fuel Leak Detection Lamp
Panel Light/Panel Light Switch
ECU Controller
Engine Speed Switch
Warning Lamp (Diagnostic Lamp)
GENERATOR CONTROL PANEL
The “Generator Control Panel” is provided with the following:
Frequency Meter (Hz)
AC Ammeter (Amps)
AC Voltmeter (Volts)
Ammeter Change-Over Switch
Voltmeter Change-Over Switch
Voltage Regulator
3-Pole, 350 amp Main Circuit Breaker
“Control Box” (located behind the Gen. Control Panel)
• Automatic Voltage Regulator
• Current Transformer
• Over-Current Relay
• Starter Relay
• Voltage Selector Switch
• Diagnostic Switch
OUTPUT TERMINAL PANEL
The “Output Terminal Panel” is provided with the following:
Three 120/240V output receptacles (CS-6369), 50A
Three auxiliary circuit breakers, 50A
Two 120V output receptacles (GFCI), 20A
Two GFCI circuit breakers, 20A
Five output terminal lugs (3Ø power)
Battery Charger (Optional)
Jacket Water Heater (Optional)
Low Coolant Level Switch
OPEN DELTA EXCITATION SYSTEM
This generator is equipped with the state of the art “Open-
Delta” excitation system. The open delta system consist
of an electrically independent winding wound among
stationary windings of the AC output section.
There are four connections of the open delta A, B, C and
D. During steady state loads, the power from the voltage
regulator is supplied from the parallel connections of A to
B, A to D, and C to D. These three phases of the voltage
input to the voltage regulator are then rectified and are the
excitation current for the exciter section.
When a heavy load, such as a motor starting or a short
circuit occurs, the automatic voltage regulator (AVR)
switches the configuration of the open delta to the series
connection of B to C. This has the effect of adding the
voltages of each phase to provide higher excitation to the
exciter section and thus better voltage response during the
application of heavy loads.
The connections of the AVR to the AC output windings are
for sensing only. No power is required from these windings.
The open-delta design provides virtually unlimited excitation
current, offering maximum motor starting capabilities. The
excitation does not have a “fixed ceiling” and responds
according the demands of the required load.
ENGINE
The DCA125USI is powered by a 4 cylinder, water cooled,
direct injection, turbocharged ISUZU 4HK1X diesel engine.
This engine is designed to meet every performance
requirement for the generator. Reference Table 2 for engine
specifications.
In keeping with MQ Power’s policy of constantly improving
its products, the specifications quoted herein are subject
to change without prior notice.
ELECTRIC GOVERNOR SYSTEM
The electric governor system controls the RPMs of the engine.
When the engine demand increases or decreases, the
governor system regulates the frequency variation to ±.25%.
EXTENSION CABLES
When electric power is to be provided to various tools or
loads at some distance from the generator, extension cords
are normally used. Cables should be sized to allow for
distance in length and amperage so that the voltage drop
between the generator and point of use (load) is held to
a minimum. Use the cable selection chart (Table 6) as a
guide for selecting proper extension cable size.
GENERAL INFORMATION

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 17
MAJOR COMPONENTS
Table 4. Generator Major Components
ITEM NO. DESCRIPTION
1 Muffler Assembly
2 Engine Assembly
3 Enclosure Assembly
4 Generator Assembly
5 Output Terminal Assembly
6 Fuel Tank Assembly
7 Battery Assembly
8 Engine Operating Panel Assembly
9 Generator Control Panel Assembly
Figure 3. Major Components

PAGE 18 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
GENERATOR CONTROL PANEL
Figure 4. Generator Control Panel
The definitions below describe the controls and functions
of the Generator Control Panel (Figure 4).
1. Main Circuit Breaker—This three-pole, 350A main
breaker is provided to protect the the U,V, and W
Output Terminal Lugs from overload.
2. Voltage Regulator Control — Allows ±15% manual
adjustment of the generator’s output voltage.
3. Ammeter Change-Over Switch — This switch allows
the AC ammeter to indicate the current flowing to the
load connected to any phase of the output terminals,
or to be switched off. This switch does not effect the
generator output in any fashion, it is for current reading
only.
4. Voltmeter Change-Over Switch — This switch allows
the AC voltmeter to indicate phase to phase voltage
between any two phases of the output terminals or to
be switched off.
5. Frequency Meter — Indicates the output frequency
in hertz (Hz). Normally 60 Hz.
6. AC Ammeter — Indicates the amount of current the
load is drawing from the generator per leg selected by
the ammeter phase-selector switch.
7. AC Voltmeter — Indicates the output voltage present
at the U,V, and W Output Terminal Lugs.
Located behind the generator control panel is the Generator
Control Box. This box contains some of the necessary
electronic components required to make the generator
function.
The Control Box is equipped with the following major
components:
Over-Current Relay
Automatic Voltage Regulator (AVR)
Starter Relay
Current Transformer
Voltage Selector Switch
Main Circuit Breaker
NOTICE
Remember the overcurrent relay monitors the current
flowing from the U,V, and W Output Terminal Lugs
to the load.
In the event of a short circuit or over current condition,
it will automatically trip the 350 amp main breaker.
To restore power to the Output Terminal Panel, press
the reset button on the overcurrent relay and place the
main circuit breaker in the closed position (ON).

DCA125USI 60 HZ GEN. • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11) — PAGE 19
NOTES

PAGE 20 — DCA125USI 60 HZ GENERATOR • OPERATION AND PARTS MANUAL — REV. #1 (03/25/11)
ENGINE OPERATING PANEL
Figure 5. Engine Operating Panel