Engines for Stationary Generator in Normal Service
in Domestic Market

Mitsuru Ueno
Takanobu Akutsu
Hiroshi Ohta
Kouji Hagiwara
Toshio Maki

As deregulation and liberalization deepen in the Japan’s domestic market of electric power supply, an
onsite power generation business has made a great stride, being spotlighted as a new system for power
supply. Traditionally power supply in this country has depended on large-scale power stations, and poweris transmitted through a power cable. Now this business mode is transforming to a highly efficient network
system that can supply as much power as required at the time and place of demand, thereby eliminatinga loss during the transmission. This system is being gradually accepted as a system conducive to the
reduction of CO2 in the air against the backdrop of environmental protection.
Presently the mainstream onsite non-utility power generation system is a generator with a diesel engine
as its prime mover. Keeping in step with the ever growing market of onsite non-utility generator sets,
Komatsu’s line of diesel engines has also made a rapid growth.
This paper introduces Komatsu’s engine technology that has been built in the diesel engines mounted
on onsite non-utility generator sets.
Key words: Power Generation, Diesel Engine, Onsite Power Generation Business1. Introduction
In recent years power supply business in the Japan’s
domestic market has undergone a big change. In particular,
competition is intensifying in the business field of onsite nonutility generators. It has been accelerated above all by theelectric power companies which regard this business as partof the service industry and took part in the field. Instead oflimiting themselves to a simple role of mere power supplier,they are deploying the business, keeping a comprehensive
energy supply in their scope.
A micro gas turbine and fuel cell, so to speak a brainchildof new dream technology, are now emerging as a power source
for the 21st century. Thus there is no doubt that power sourcesin this country will be diversified and an onsite non-utility
generator will play a leading role of power source in the next
generation.

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Against such a backdrop of the industry, Komatsu-madediesel engines are being rapidly and extensively accepted in
the market as a prime mover of generators in general. This
fact is supported by statistics that while the market in this
sector is said to have grown by 50% over the past three years,
our diesel engines registered a growth rate of 40% two years
ago (1999) and 22% last year (2000) respectively. (Source: Japan
Engine Generator News)
This paper takes up a lineup of our diesel engines forstationary type of generators in normal service and discusses
their features as well as technology supporting the products.

Engines for Stationary Generator in Normal Service
in Domestic Market— 35 —

2. Product lineup
Komatsu diesel engines are now provided in six series foran application to generators in normal use, namely 108, 125,
140, 170, 140V and 170V series. Fig. 1 below shows major
specifications of each series.
Boosters of the growth of the demand for onsite non-utility
generators in the domestic market are large supermarkets inthe outskirts of big cities, plants, hospitals, hotels and schools.
Generators are installed in those buildings primarily for keeping
down electricity bills. In the past when we thought of power
generation facilities, we would build up an image of a power
station that required a large-scale investment and generated
tens of thousands of kilowatt electricity. Contrary to suchgeneral perception, the current main stream is several units ofgenerator having a capacity of 200 to 500 kW that are installed
in a package. Moreover the size of this package shows a trendof getting ever-larger. As a result, there is increasingly ademand for Komatsu’s SA12V170 diesel engines, the largest inclass, for generators of 800 kW capacity.
A basic factor about a non-utility generator in normal
service is that its load factor exceeds 90%. For this reason,
the output of our diesel engines for generator application isset after that of bulldozers, the choice from among theKomatsu’s range of construction machinery. But in the recent
highly competitive environment of the market, a whole power
generation unit is offered on a renting basis. This is anincreasingly prevailing new business model lined with an ideathat customers can thereby save an investment for a dieselpowered generator set. Consequently it has given a birth toan index called a “kW Unit Price” which expresses a costrequired to generate 1 kW of electricity, and this index has
become an important benchmark. Now customers’ expectation
for a low initial cost as well as low running cost is rising high.
To cope with this trend, we have switched from an aftercooler
system which utilizes engine cooling water and which has been
widely in use for construction equipment so far to an air-to-air
aftercooler system. The latter is applied to more and morediesel engines of Komatsu to form a new series, which makes
up our important strategy for widening the engine series.

6D108
7.15r

Output of Engine with Fan (kW)

1000

6D125
11.04r

6D140
15.24r

6D170
23.15r

3. Characteristics required of generators innormal ser vice and realizing technology
3.1 Fuel consumption amountThe primar y characteristic required of a generator innormal service is the engine fuel consumption ratio. For power
generation systems using a diesel engine as the prime mover,fuel accounts for approx. 70% of the total cost. Thus the fuelconsumption is a domain where an economical merit can best
be demonstrated. Meanwhile, Komatsu has consummatedtechnologies for producing small-sized but high horsepowerengines.
To name a few of them:• Piston made of ductile cast iron (Fig. 2)• Cylinder liner by Tuftride method (Fig. 3)• Cylinder head having dual air intake ports (Fig. 4)• Air-cooled aftercooler (Fig. 5)

FCD Piston
Aluminum Piston
Fig. 2 Ductile cast iron-made piston
Feeding oil
Oil Sump
Plateau

Cylinder LinerFig. 3 Tuftride cylinder liner

Intake air in spiral flow
causing strong swirl

TA(2)
TA
T
12V140
12V17030.48r
46.30r(3)(3)(3)(1)(2) (1)(2)(3)(2)(3) (2) (1)(3)(1)(2) (1)(2)(3) (2)(3)(1)(3) (2)(3)(1)(2) (1)(2) (1)(3)(3)(1)(2) (1)(2)(1)

Flow of intake air

Fig. 4 Dual air intake ports

100

50Hz 60Hz 50Hz 60Hz 50Hz 60Hz 50Hz 60Hz 50Hz 60Hz 50Hz 60Hz
10(1): Onsite non-utility generator (installed as a power source mainly forlarge stores, plants, etc. and run continuously at a rated speed)(2): Transportable type generator (installed as a power source mainly forconstruction sites and can be moved from one jobsite to another)(3): Generator for disaster (operated as an emergency power source in case of
power failure due to a disaster)Fig. 5 Air-cooled aftercooler

Fig. 1 Output range of Komatsu engine for generator application

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Engines for Stationary Generator in Normal Service
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regulation. Concentration of NOx in the emission gas is affectedby humidity in the atmosphere. For this reason, the engine
injection timing is set, taking into account possible changes ofhumidity in the atmosphere throughout the four seasons, and acomplete engine clears a pre-delivery inspection that imposes
stricter restrictive values than those specified by any municipality.
In addition, soot contained in the emission gas from theengine creates another problem, as generators are usually
installed in the living quarters of citizens. It is also an
important assignment for us to reduce the soot level. To attainthis assignment, we have take steps to ensure that sufficientamount of air is fed into the engine through optimum tuningof the turbocharger and built in the fuel injection nozzles a
special machining engineering that helps atomize fuel further.
(Extrude horn nozzle. See Fig. 7)

3.2 Control of exhaust gas
In 1988 it was enacted in Japan to include onsite non-utility
generators using a stationary internal combustion engine in
the scope of Air Pollution Law. As a result, nitride oxide (NOx),soot and sulfur oxide emitted from the engine are now undercontrol. With non-utility generators in particular, Air Pollution
Law has been turned even more rigorous in its implementation,
as each municipal government voluntarily imposed stif fer
restriction values that exceed the original values set by thelaw. Thus power generation facilities relying on a diesel engine
are placed under very strict conditions of use particularly in
big cities. (See Fig. 6)
As understood from Fig. 6 below, most of the restricted
municipalities fall within the category of 950 ppm regulations(in terms of 13% O2). But Air Pollution Law resorts to a site

Air Pollution Law(Ministry of the Environment)

950 ppm

Above 50r/h in terms of fuel oil A

Osaka Prefecture
Osaka City
Other restricted areas
Non-restricted areas
Sakai City
Kobe City
Karita Township in
Kita Kyushu City

(114 ppm)
700 ppm(114 ppm)(114 ppm)(190 ppm)

Above 30r/h in terms of fuel oil A

Above 50r/h in terms of fuel oil A

400 ppm

Nagoya City

113 ppm
171 ppm

Shimizu City in
Shizuoka Prefecture

Above 50r/h in terms of fuel oil A

100 ppm

Above 50r/h in terms of fuel oil A
Emission gas volume above 5000 m3 N/h

Chiba Prefecture
Chiba City
Special Areas
Other Areas

Greater Tokyo
1st grade areas
2nd grade areas

Above 50r/h andbelow 200r/h in terms of fuel oil A
Above 500 kW
Below 500 kW(750 ppm)

760 ppm

Saitama Prefecture

Above 25r/h in terms of fuel oil A

As per Air Pollution Law but accompanied byadministrative guidance in individual cases

Aichi Prefecture(excluding Nagoya City)

Fukushima Prefecture

Restriction values not disclosed(value specified by Air Pollution Law Above 50r/h in terms of
Yamanashi Prefecture ⫻ 0.8, this is equal to 760 ppm)
fuel oil A(114 ppm)(497 ppm)

Kanagawa Prefecture
Yokohama City
57 ppmKawasaki City & Yokosuka City 110 ppm
Other areas

190 ppm

100 ppm
100 ppm
150 ppm

Above 50r/h in terms of fuel oil A

Above 50r/h in terms of fuel oil A
Below rated horsepower of 2000 kW

Below rated horsepower of 2000 kW
Above 50r/h in terms of fuel oil A
Above 50r/h in terms of fuel oil A
Below 200r/h in terms of fuel oil A

Fig. 6 Stiffer restriction values of municipalities based on the Air Pollution Law

Round orifice edge by grain horning
grain

roundedStandard nozzle
High flow rate
Enabling injection orifice to be further narrowed
Injected fuel further atomized
Improving emission gas color

High flow rate nozzle

Fig. 7 Extrude Horn Nozzle

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3.4 Use of electronic control technology
An electronic controlled fuel injection pump is installedon the current diesel engines for stationary generators innormal service as a standard specification, which represents
merits through control technology.
A few examples for these merits are:q In acceleration from Li to Hi, fuel injection amount is
controlled through a ramp-up acceleration control in sucha way that while the engine speed is swiftly raised (inabout 10 seconds), the exhaust gas color is kept hardly
visible (see Fig. 8).

3.3 Noises
Non-utility generators in normal ser vice are sometimes
kept in operation around the clock. Therefore, it is again an
important task to incorporate a noise abating technology into
the engine in order to reduce noises to the neighborhood
during the midnight. A hybrid fan that Komatsu has developed(see Photo 1) has a unique feature in its blade configurationand has successfully brought down the noise level while
assuring the same amount of air feed. Komatsu’s noise abating
technologies have also been built in the basic components ofan engine, such as a gear train which has reduced backlashand cylinder block which has enhanced the rigidity.

Engine speed ramping
up period short

Low idling

Rotation
speed

Rated rpm

Hybrid fan

Engine speed
ramping up period longTime

Fig. 8 Ramp-up acceleration control

w In consideration of the best matching with the generatorof each manufacturer whose characteristics differ from one
maker to another, an external adjustment volume isprovided which enables a PID control constant to bevaried.
e A failure self-diagnosis function is provided as a standard
specification (see Table 1). It receives and processes a
signal from the generator.
Table 2 shows an assor tment of functions that aresupported by electronic control technology.

Photo 1 Hybrid radiator cooling fan

Table 1 Example for failure self-diagnosis function
Item

Failure judgment method

NormalTime required forjudgment

ActionPossibilityof autorecoveryRecovery Condition

EnginestatusLamp(alarm)outputLED
numeric
display———

Running

—

00

—

—

RAM in error

Write and read being incompatible attime of system ramping-up

Numeric[msec]

33

Governor servo
in error

Difference between rack target value
and measured value being over
1 [mm]Ne 158 [rpm] / 10 [sec]Ne > 158 [rpm] / 5 [sec]Refer toleft

11

Rack sensor
abnormal

When rack sensor output voltage getsout of the specified range:
Above 4.5 [V] or below 0.15 [V]150[msec]

42

Overrunning{Software overrunning}• Stationary and normal service• Normal
specifications:service
Governor
When set at 50 Hz, Ne 1725 [rpm] spec.
When set at 60 Hz, Ne 2070 [rpm] 2.0 [sec] pull-down• Transportable specifications:
When set both at 50 Hz and at• Portable
60 Hz, Ne 2070 [rpm]spec.
{Hardware overrunning}100
Ne 2600 [rpm][msec]

None

Turn the power OFF
once and start the systemagain.
If no such phenomenon
as described at left does
not occur again, thesystem has been
recovered.

Stop

17 pins

20 & 21

Turn the hydraulic switch ON after
Oil pressure low 6 [sec.] at Ne 500 [rpm]500[msec]

01

Cooling water
Turn the cooling water temperaturetemperature high switch ON.

0.3
[sec]

03

Numeric[msec]

55

Source voltage
abnormal

Source voltage has varied by morethan 30[%] (8.4 V) as against thestandard voltage (28 [V]) after
10 [sec] at Ne > 1393 rpm

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Engines for Stationary Generator in Normal Service
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Table 2 Kinds of control by generator controller
No.

Control item

Summary of control

1

Switching frequency (50 / 60 Hz)

Frequency can be switched between 50 Hz and 60 Hz by turning on and off a jumper wire on
the monitor panel. Switching frequency is not possible while the engine is running.
(Frequency can be switched only when power is switched OFF.)2

Switching between Li and rated rpm

Engine speed can be switched between Li and the rated rpm through switching input from thecontrol panel on the generator. It can be switched when the engine is running(power switch ON).

3

Adjusting Li rotation speed

The Li rotation speed can be adjusted with a volume switch on the control panel.
Adjustment range: 800 rpm ± 100 rpm

4

Switching speed droop andisochronous operation

Control of the rated rpm can be switched between speed droop control (No.5) and isochronous
control (No.6) by turning on and off a jumper wire on the control panel.
Switching is not possible when the engine is running. (Switching is possible only whenpower is switched OFF.)

5

Engine running under speed droop
control

When jumper wire (No. 4) for switching between speed droop and isochronous operation is at
the speed droop position, run the engine under speed droop control (the rotation speed
changes as load changes). Adjust the rotation with any one of pulse signal (No. 7), analog
signal (No. 8) and volume switch on the control panel.

6

Engine running under isochronous
control

When jumper line (No. 4) for switching between speed droop and isochronous operation is at
the isochronous position, run the engine under isochronous control (the rated rpm remains
constant irrespective of changes in load). Adjust the rotation with either of analog signal(No. 8) and volume switch on the control panel.

7

Adjusting rated rpm pulse signal(Under speed droop control)

Adjust the rated rpm with a pulse signal input from the control panel on the generator.
Adjustable range for speed: Approx. 3 rpm/sec. (generators in normal service),
approx. 5 rpm/sec. (transportable type generators) and judgment: 50 msec.

8

Adjusting rated rpm volume(Under both speed droop andisochronous controls)

Adjust the rated rpm with the volume switch on the control panel.
Judgment: 15 msec.

9

Adjusting rated rpm analog input(Both under speed droop control
and isochronous control)

Adjust the rpm with an analog signal input from the control panel on the generator.
Adjustable signal range for speed: DC 1 – 5 V

10

Switching between rotation
adjustment analog and pulse signals(Under speed droop control)

The rated rpm adjustment method can be switched between pulse signal input (No. 7) andanalog signal input (No. 9) by turning on and off a jumper wire on the monitor panel.
Switching is possible even when the engine is running (when power switch ON).

11

Switching between rotation
adjustment analog and volume signals(Both under speed droop control
and under isochronous control)

The rated rpm adjustment method can be switched between volume switch adjustment (No. 8)
and analog signal input (No. 9) by turning on and off a jumper wire on the monitor panel.
Switching is possible when the engine is running (when power switch ON), but anerror mark is shown on the display.

12

Speed droop adjustment(Under speed droop control)

Regulation can be changed with the volume switch on the control panel when the engine isrunning at the rated rpm.
Adjustment range: Approx. 3 – 5 %13

Excessive acceleration limiting
function(Speed lamp function)

When the rated rpm is selected with the Li/rated rpm selector switch, this function controls
the time required for the engine rotation to rise from Li to the rated rpm (approx. 10 sec.),
thereby keeping down black smokes. The function is also activated when the engine starts up
with the selector switch at the Hi position.

14

Switching speed lamp ON and OFF

Use or nor use of the speed lamp control can be selected by turning on and off a jumper wireon the monitor panel. Switching is not possible when the engine is running.
(It is possible only when the power switch is OFF.)

15

Emergency stop function

The engine is stopped automatically when a serious trouble occurs, such as when the engine
oil pressure lowers abnormally; the engine cooling water temperature rises abnormally; or theengine is overrunning.

16

Failure self-diagnosis function

If any abnormality occurs on the electronic governor system, this function is activated to takespecified corrective actions and sends out a failure signal.
Output: Numeric display on the controller and failure- indicating lamp going on(For more details, see Troubleshooting Table.)

17

Memory clearing function

History of the failures stored in the memory can be cleared by pressing the memory clearing
button on the control panel.

18

Switching to excessive speed testingmode(Not to be used in other than test)

Testing an excessive speed is made possible by turning on and off a jumper wire on themonitor panel. Do not use this mode while the engine is running. (It may be switched
only when the power switch is OFF.)19

PID adjustment function

Control constants can be changed with the volume switch on the control panel so that thegenerator can be set at an optimum value in terms of its stability and responsiveness.

20

ON/OFF switching for PID
adjustment“Allowed” or “Not Allowed” of adjusting PID constants can be selected by turning the volume
on the control panel through the function of the jumper wire on the control panel.
(Not Allowed = using a constant from the internal data)
Switching is not possible when the engine is running. (It is possible only when the
power switch is OFF.)21

Output of engine starting motor
pinion slip-off signal

Engine startup is detected and a relay signal is sent out.

22

Engine pre-lubrication function

Cranking without fuel injection is made possible by the switch on the control panel.

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3.5 High reliability and durability
Generators in normal ser vice are required of highreliability and durability for its nature of fundamental facilities.
In this respect, Komatsu has held up 16000 hour overhaul-freemaintenance schedule of the engine as one of its sales features
ahead of the other competitors. Based on the use in theconstruction equipment, history of individual engine parts isstored in a database. Then far-flung improvement of the engine
parts has been devised, making use of such database and taking
into account peculiarities in the application of the engine togenerators in normal service. Included in the improvement
are a change of the shaft seals for a longer service life, changeof the material used in the fuel injection system from a rubber
hose to metal piping, engine oil selection standard to matchthe nature of fuel, increasing the oil pan capacity, providing a
bypass filter as a standard specification, increasing the fuel filter
capacity (to deal with fuel oil A), anti-corrosive measure against
sulfur content in fuel, etc. An assortment of such improvements
enabled us to achieve a 16000 hour overhaul-free maintenanceschedule of our engines.
In addition, the table for scheduled engine maintenancehas been revised, setting up an inspection inter val as A
Inspection (every 500 hours), B Inspection (every 1000 hours),
C Inspection (every 2000 hours), D Inspection (every 4000
hours), E Inspection (ever y 8000 hours) and F Inspection(every 16000 hours). A maintenance work standard and a table
for replacement parts at each inspection time are prepared.
Potential clients of Komatsu engine-mounted generators makethe most of these informative materials when computing agenerator running cost.

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4. Future prospect
Competition in the onsite non-utility generator in normal
service is stiffening, as the market continues to expand. As
we discussed in the preceding chapter, a mission of onsite nonutility generators lies in proving its economy. How can ourdiesel engines be an economical prime mover under theprevailing stringent environmental restrictions? That will
decide whether we can stay in the market as a winner in the
future. At any rate, irrespective of how the market evolves
from now on, I trust that the two fundamental requirements ofthe market, namely q less fuel consumption mount andw lower maintenance cost will remain unaffected. There
should be no change in clients’ aspiration of them from now,either.

5. Conclusion
Sales of Komatsu diesel engines for generator application
has grown so high that currently the sales ratio accounts formore than 50% of the total demand including those for otherapplications. This is fruit of all the efforts and hard work of
those who have been engaged in the generator engine businessto date. It is believed that a demand for power will be still on
the rise in the 21st centur y, too, and that enhancing
merchantability of the products even more is essential toremain in the market. In this regard, we are fortunate topossess an FCD piston-based low fuel consumption technology
and a construction equipment-based technology for prolonging
replacement par t ser vice life, which surely meet withrequirements in the today’s market. It is no exaggeration toclaim that thanks to those technologies, Komatsu’s engine
brand is disseminating in the domestic market stationary nonutility generator sets. We will maintain the brand while making
further improvements on our engines. To do this, we needfeedback of a wide spectrum of market information and above
all voices from clients about their requirements. We will keepa clearer focus on them.

Engines for Stationary Generator in Normal Service
in Domestic Market— 40 —

Introduction of the writers[A few words from the writers]

Mitsuru Ueno
Entered Komatsu in 1984.
Currently ser ving as Executive Vice
President of IPA Inc.

Takanobu Akutsu
Entered Komatsu in 1983.
Currently working in Applied ProductDevelopment Group, IPA Inc.

A number of Komatsu-made diesel engines have been so far
adopted by the Japan’s generator manufacturers as an OEM engine.
You may come across one in a shopping center or plant in yourneighborhood that is working day and night. Basically it is a resultof the engine per formance (like fuel consumption as reported inthis paper) that has been accepted by the clients. But broadly it
should be a result of the joint ef forts of all the Komatsu people
concerned that went into the improvement of reliability anddurability of the engine as well as after-sales service including
replacement parts supply system.
We pledge to continue with our ef for ts for improving ordeveloping our diesel engines from now on, too, to ensure a supply
of “inexpensive power of high quality” to our clients at large.

Hiroshi Ohta
Entered Komatsu in 1981.
Currently working in Applied ProductDevelopment Group, IPA Inc.

Kouji Hagiwara
Entered Komatsu in 1993.
Currently working in Applied ProductDevelopment Group, IPA Inc.

Toshio MakiEntered Komatsu in 1995.
Currently working in Applied ProductDevelopment Group, IPA Inc.

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