Answers for energy.

POWER-GEN Europe 2012,Cologne, GermanyJune 12–14, 2012

Authors:Petra MichalkeSiemens AGEnergy Sector – Service Division

Thomas SchmuckSiemens AG Energy Sector – Service Division

Powerful Products for the Enhanced Flexibility of Gas Turbines

www.siemens.com/energy

2

ContentAbstract 3

Introduction 4

Enhanced flexibility for E-class gas turbines 5

Power Limit Increase 6

Wet Compression 7

Enhanced flexibility for F-class gas turbines 8

Advanced Stability Margin Controller 9

Advanced Compressor Mass Flow Increase 9

Turn Down 10

Turn Up 11

Wet Compression 12

Operational Flexibility Upgrade 12

Conclusion 13

References 13

Permission for use 13

Disclaimer 13

Copyright © Siemens AG 2012. All rights reserved.

3

Abstract

With a steadily growing share of renewable sources of power generation and the ongoing development of com-petitive electricity and gas markets, the need is emerging for additional flexibility in our advanced gas turbines. The Advanced Compressor Mass Flow Increase and Advanced Stability Margin Controller upgrades provide our customers with the opportunity of additional flexible power and an economical alternative to additional genera-tion equipment.

The Advanced Compressor Mass Flow Increase upgrade is part of the SGT5-4000F (V94.3A) new apparatus design based on the proven SGT5-8000H design. The new 3D compressor blade and vane profile is highly efficient, resulting in a compressor mass flow increase and conse-quently in a power increase of up to 10 MW for the gas turbine and 14 MW in combined cycle (1x1) operation. The Advanced Compressor Mass Flow Increase upgrade is retrofittable in the SGT5-4000F (V94.3A) service fleet.

The Advanced Stability Margin Controller continuously monitors combustor behavior. The resulting feedback enables automatic engine tuning and automatic engine protection. In addition, the operator is informed about potential issues with the combustion process. For natural gas operation, the pilot gas volume and the turbine outlet temperature are modulated by an automated control logic to prevent the engine from high combustion chamber ac-celeration events. This supports engine operation with an optimal power output at the lowest combustion dynamics.

Fast de-loading, gas turbine trips, and subsequent com-bustion-chamber inspections can be avoided by increased combustion stability during part and base load operation.

By implementing the Advanced Compressor Mass Flow increase and/or the Advanced Stability Margin Controller upgrades, gas turbines can remain highly reliable and competitive in the continuously growing F-class market.

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Introduction

Gas turbine design and manufacturing technologies have advanced significantly in the years since the first gas tur-bine VM1 was designed in 1956. More than 14 different gas turbine types have been developed by Siemens since then, reflecting the evolution of the electricity market, changing environmental requirements including steward-ship of available fuel resources, and the globalization of the energy market.

The need for peak load and reserve capacity has been continuously increasing in recent years. With a growing quantity of regenerative energy generation (wind, solar) being added to power systems worldwide, the require-ment for reserve capacity that can be provided on demand is also increasing. In Germany, for example, installed wind generation capacity accounts for more than 26 GW installed capacity, and significant additional generation is being added through new offshore wind parks. The proportion of the actual energy contribution from wind generation in Germany is typically between five and ten percent of annual energy generation, with generation duration of approximately 18 percent on an annual hourly basis. Clearly, reserve peaking capacity needs to be avail-able on short notice when needed by the power system to support renewable generation. As new projects usually require protracted development periods due to long lead times for site permitting and construction, an appropriate alternative is to increase the capacity of power plants already in existence. [1]

Fig. 1: Development path of V-frame gas turbines

New design and manufacturing technologies – including advances in design and modeling technologies and the refinement of design criteria as well as advances in material, cooling, and coating technologies – have also been used to develop upgrades and component enhance-ments for the existing fleet. As the original equipment manufacturer (OEM), Siemens has a huge advantage, and continuously introduces technical enhancements within its new unit and service business. The main market drivers for gas turbine modernization within the service business are the following:■■ Power output increase■■ Efficiency improvement■■ Operational flexibility■■ Reduction of maintenance efforts■■ Emission reduction■■ Improvement of reliability and availability

Selected products and technical solutions that enhance the operational flexibility of V-frame gas turbines will be explained in the following sections. These products will improve grid or peak load capacity and part load operation capacity and will expand existing maintenance concepts.

Years

1960

VM1 1956

VM5 1960

VM80 1961

VM43 V93.0 1972

V94.0 1974

V94.1 1980

V64.3 1990

V84.3 1994

V82.0SGT5-2000E (V94.2) 1981

SGT5-1000F (V64.3A) 1997

SGT6-2000E (V84.2) 1989

SGTx-4000F (Vx4.3A) 1996

SGT5-3000E (V94.2A) 2000

SGT6-8000H 2011

SGT5-8000H 2007

V94.3 1995

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Technology

5

The SGT5-2000E (V94.2) is an extremely well-proven, robust engine for the 50 Hz market and is used for simple or combined cycle processes with or without combined heat and power production in all load ranges, especially in peak-load operation. The SGT5-2000E (V94.2) was introduced in the early 1980s and was installed almost 300 times with its 60 Hz equivalent, the SGT6-2000E (V84.2). Together this fleet has accumulated more than 20,000,000 equivalent operating hours (EOH). Several modernization and upgrade solutions have been devel-oped over the past 30 years reflecting various market needs, for example, the changing requirements for reserve capacity and flexibility.

Fig. 2: Customer-driven service product development SGT5-2000E (V94.2)

Siemens’ most powerful modernization products for enhancing the E-class gas turbine’s flexibility are the Wet Compression upgrade and the Siemens innovative 3D-optimized (Si3D) turbine efficiency upgrade. With the introduction of the Power Limit Increase to the SGT5-2000E (V94.2), the remarkable advantages of the optimized tur-bine blades and vanes are used to achieve an even greater increase in capacity.

Enhanced flexibility for E-class gas turbines

Siemens innovative 3Doptimized blades and vanes 1+2

Wet Compression

Siemens innovative 3D optimized blades and vanes 3+4

Ongoing DevelopmentPower Limit Increase (PLI)

Compressor Mass Flow Increase

41MACFiring Temperature IncreaseHR3 Burner

33MACTurbine Section Upgrade

203 Units in Commercial Operation*

Total EOH > 14,800,000Lead Unit EOH > 266,000

1981

1986

19892003

2001

2008

2013

2006

[118 MW; 32,4 %]

Power Output

Eff

icie

ncy

[178+ MW; 36+ %**]

[173 MW; 35,8 %**]

Additional Modernization & Upgrades

■■ Advanced Compressor Coating

■■ EVAP Cooler

■■ Fuel Gas Preheating

■■ Fuel Conversion* As of March 2012** Expected values only, site specific values may vary

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Fig. 3: Customer-driven service product development SGT5-2000E (V94.2)

Power Limit Increase

Our latest development, specially designed for combined heat plants (CHP) as well as for high power applications like Wet Compression, is the Power Limit Increase (PLI), which is based on the Siemens innovative 3D-optimized (Si3D) turbine efficiency upgrade.

With the latest Siemens innovative 3D-optimized turbine blade and vane technology for the mature SGT5-2000E (V94.2) frame, and based on the successful validation test results in the winter of 2012, Siemens is currently preparing the fleet release to expand the current power limit from 173 MW to 185 MW for all SGT5-2000E (V94.2) units equipped with Siemens innovative 3D-optimized turbine stages one to four. However, the unit-specific scope may differ and is subject to a site-specific evaluation. This not only means more power over the entire temperature range, it also means additional output in the temperature range below the current power limit, which was not acces-sible with gas turbine units of older design phases.

In addition, CHPs are operated primarily in northern coun-tries where the demand for electricity meets an effective way of producing district heating for households or industry. District heating output at low ambient temperatures is limited by the current power limit of the rear stages gas turbine blades. With falling ambient temperatures, power plants with service-exposed SGT5-2000E (V94.2) units are affected in such a way that the closing inlet guide vanes that limit the gas turbine’s power also throttle the district heating output. This forces the power plant operator to provide the extra heat energy required from other resources, which usually operate less efficiently than the CHP. [2]

Compared with the reference case of a SGT5-2000E (V94.2) from an older design stage, an increase of up to four percent of exhaust gas energy can be utilized over a wider ambient temperature range. This huge performance increase helps strengthen power plant operators’ market position.

Compressor inlet temperature [°C] *TT1iso

Reference V94.2 at 1060°C*

V94.2 with Siemens innovative threedimen-sional optimized stages 1-4 and PLI at 1065°C*

V94.2 with Siemens innovative three-dimensional optimized stages 1-4 and PLI at 1080°C*

V94.2 with CMF+, Siemens innovative three-dimensional optimized stages 1-4 and PLI at 1080°C*

Gas

tu

rbin

e p

ow

er

ou

tpu

t [M

W]

185 MW Additional benefit of power limit increase 173 MW

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Wet Compression

The Wet Compression upgrade is a reliable and proven method of injecting water into the gas turbine inlet. Wet Compression is perfectly suited for upgrading peak load gas turbines. Providing peak power enables electricity producers to react to increased grid power demand, for example, dur-ing summer peaks or grid fluctuations driven by renewable energy sources, and increases customer revenues at high peak load electricity prices. Wet Compression is designed to increase power output up to 18 MW by injecting water into the compressor inlet, which inter-cools the compressor, reduces the compressor inlet temperature, and increases mass flow throughout the gas turbine.

Wet Compression can be used for various purposes: the most common and commercially attractive ones are:■■ Seasonal operation (summer peak operation) ■■ Reserve power and occasional peaking■■ Grid support■■ Base load increase for simple cycle gas turbines

The seasonal operation of Wet Compression to compensate for capacity losses during high ambient temperature con-ditions is possible in both dry and humid areas. Moreover, a combination with an evaporative cooler or chiller is possible as long as the compressor inlet temperature stays above 10° Celsius. Implementing the Wet Compression upgrade to increase the marketable power reserve and for occasional peaking is ideal, because the impact on the normal operation of the gas turbine is very minimal.

Wet Compression was developed in 1995 and redesigned for the SGT5/6-2000E (V84.2 / V94.2) in 2003. More than 45 Wet Compression systems have been installed and operated on Siemens E-class gas turbines since that year.

20

18

16

14

12

10

8

6

4

2

010 20 30 40 50 60 70 80 90 100

Base load power, dry

Power output with Evaporative cooler (85 % Eff.)

Power output with Wet Compression (2 %-MVI)

Power output at 30 °C ambient temperature related to the relative humidity

De

lta

po

we

r o

utp

ut

(to

Bas

e L

oad

, R.H

. 10

%)

[%]

Relative humidity [%]

Fig. 4: Comparison of Wet Compression power output with an Evaporative Cooler at a variation of relative humidity

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Fig. 5: Customer-driven service product development SGT5-4000F (V94.3A)

The proven SGT5-4000F (V94.3A) is characterized by high performance, low power generating costs, and long inter-vals between major inspections as well as an easy-to-service design. Since 1996 more than 200 units have been installed worldwide. Its 60 Hz equivalent SGT6-4000F (V84.3A) was introduced in 1997 and has been sold more than 50 times since then. Together this fleet has accumu-lated more than 10,000,000 EOH. The SGT5-4000F (V94.3A) is based on the SGT5-2000E (V94.2) and on proven standard design concepts. With optimized flow, combustion, and cooling systems as well as new materials, a gas turbine efficiency of nearly 40 percent ensures a strong position in a competitive market.

Market requirements have been trending toward fast start-up times, higher load gradients, and peak load capacity. Research predicts the development of market demand in the direction of even higher flexibility required of gas tur-bine operation modes. Our most powerful modernization and upgrade products that meet the challenges of the changing power generation market and enhance the F-class gas turbine flexibility are the following:■■ Advanced Stability Margin Controller (aSMC)■■ Advanced Compressor Mass Flow Increase (CMF++)■■ Turn Down ■■ Turn Up■■ Wet Compression ■■ Operational Flexibility Upgrade (OFU)

Enhanced flexibility for F-class gas turbines

1) As of March 20122) 17-stage Compressor

3) Since 1998: 15-stage compressor4) Expected values only, site specific values may vary

Additional Modernization & Upgrades

■■ Advanced Compressor Coating

■■ EVAP Cooler

■■ Advanced Stability Margin Controler

■■ Advanced Compressor

Cleaning System

■■ Foreign Object Detection System

■■ Wet Compression

■■ Fuel Conversion

Power Output

Eff

icie

ncy

19973)

208 Units in Commercial Operation 1)

Total EOH > 7,734,000Lead Unit EHO > 119,000

1996 2)

[240 MW; 37.0 %]

Ongoing Development

■■ Further Firing Temperature Increase

■■ Grid and Peak Load Products

2003

SP6

SP42004

2005

2008

2010

2011

[292 MW; 39.8 % 4)]■■ Advanced Compressor Mass Flow Increase

■■ Operational Flexibility Upgrade OFU

■■ Thermal Performance Upgrade■■ Improved Hot Gas Parts

■■ Burner Upgrade (Low-NOx -> Premix-Pilot)■■ Cooling Air Reduced Combustion Chamber

■■ Burner Upgrade (Reduced Swirl)■■ Fuel Gas Preheating

■■ Compressor Mass Flow Increase■■ Turndown■■ Hydraulic Clearance Optimization

■■ HR3 Burner■■ Firing Temperature Increase■■ 15 Stage Compressor

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Advanced Compressor Mass Flow Increase

Advanced Stability Margin Controller

The Advanced Stability Margin Controller increases combustion stability during part and base load operation, allowing more flexible operating conditions in part load and a fast reaction to grid code fluctuations. The combustion dynamic monitoring system continuously monitors com-bustor dynamic pressure fluctuations to provide feedback for automatic engine tuning, automatic engine protection, and to alert the operator to potential issues with the com-bustion process.

The combustion tuning potential by pilot-gas variation at low load is limited due to upcoming combustion insta-bilities and cold or hot spot problematic. An increased pilot gas mass flow reduces the cold spot problem but increases combustion instability.

A decreased pilot gas mass flow reduces combustion instability but increases the cold spot problem. Therefore there is only a small range available for pilot gas tuning. Depending on combustion stability, the pilot gas mass flow or the turbine outlet temperature are modulated to achieve a stable combustion. The Advanced Stability Margin Controller provides closed-loop control of the combustion acoustic and the simultaneous evaluation of control parameters, resulting in a real-time adjustment to changing gas quality, ambient conditions, and power output. The Advanced Stability Margin Controller is based on extensive knowledge and experience in gas turbine combustion acoustics. Siemens Energy has extensive experiences with more than three million accumulated EOH worldwide.

Fig. 7: Gas turbine rotor with advanced compressor blades

100

80

60

40

20

200

150

100

50

014:10:00

Hu

Flg_

EnvS

PEC

[mbar] [Hz]

14:15:00 14:20:00 14:25:00

Fig. 6: Combustion acoustics under active Advanced Stability Margin Controller during operation

This evolutionary component upgrade is based on the well-proven Compressor Mass Flow Increase (CMF+) introduced in 2003. The Advanced Compressor Mass Flow Increase (CMF++) enhances the gas turbine’s power out-put up to 10 MW, and even up to 14 MW in combined cycle operation (1x1). The established Compressor Mass Flow Increase upgrade is the state-of-the-art in the new appara-tus business for the F-class gas turbines and has accumu-lated more than 1,800,000 EOH since its first introduction in 2003. The Advanced Compressor Mass Flow Increase is its subsequent development and includes an aerodynamic redesign of the first six compressor stages.

It realizes the latest advances: for example, a scoop design of compressor row one. The improvements are based on the SGT5-8000H compressor hardware design. The huge performance increase is realized with no material changes, no changes in flow paths, and with no impact on the EOH accumulation.

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Fig. 8: A higher turbine outlet temperature at part load can lead to increased combined cycle efficiency

OTCBase Load OTCPart Load OTC

(˜constant)

OTC = correct turbine outlet temperatureCO = carbon monoxideConceptual illustration only – actual results and experience may vary

Power

CO = constant

Inlet guide vane fully closed with Turn Down

Change

OTC

Use Turn Down

CO Limit

Potential Benefit through increased power range

without Turn Down

with Turn Down

Inlet guide vane fully open

Inlet guide vane fully closed without Turn Down

Turn Down

A growing number of operators are requesting wider ranges for part load operation, with the gas turbines still achieving their emission requirements. With respect to combined cycle power plants, this is constrained by the need to keep the turbine outlet temperature at the high base load level, allowing the steam turbine to be operated at a high efficiency level as possible. The implementation of the Turn Down upgrade is designed to answer the oper-ator’s demand for lower gas turbine part load operation at high combined cycle power plant efficiency levels. After implementing a new linearization unit for the inlet guide vane and a new positioning sensor, the closed position for the inlet guide vane is adjusted to a new set point, which results in an increased power range with low emissions and constant turbine outlet temperatures. The actual minimum part load depends on site-specific conditions and the desired carbon-monoxide emission level. The set point for the minimum part load is usually lower than 40 percent base load.

The Turn Down upgrade is the state-of-the-art for new Siemens gas turbines for the F-class market and may be combined with other modernizations. Since its first application in 2003, more than 100 gas turbines have been in commercial operation worldwide with more than 2,000,000 EOH.

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Turn Up

The frequency response capability of combined cycle power plants is generally activated by modulating the gas turbine output. The steam turbine follows the gas turbine’s changes with a physical delay in steam generation. The Turn Up upgrade can be implemented in order to combine the full availability of both the minimum primary and secondary frequency reserve for a high continuous plant output above 100 percent.

Turn Up refers to opening the compressor inlet guide vane beyond its standard design position, with an increase of six degrees toward the open position. This leads to an increased compressor mass flow resulting in an increased gas turbine power output of up to six MW, while the compressor efficiency remains nearly constant.

Fig. 9: Upgrade benefit: gas turbine operation closer to base load

Due to the fact that Turn Up provides power above base load, operation closer to the maximum efficiency point can be realized while still preserving the entire primary frequency response reserve. Consequently, the gas tur-bine operates at higher part load. Because the Turn Up upgrade is designed for the optimization of primary frequency response, fast load gradients are applied. The average power output of the plant will increase; a minor increase in average combined cycle efficiency can also be expected.

GT load

96 %

4 MW 4 MW

Turn Up

ηGT

97.5 % 100 % ~101.5 %

Starting point with standard configuration

Starting point with Turn Up

Base Load

Maximal Load with Turn Up

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Wet Compression

As already described, the Wet Compression upgrade was successfully introduced in the E-class gas turbines and was redesigned for the F-class market to meet their changing requirements regarding plant flexibility and capability. The commissioning of the first application on the advanced frame SGT5-4000F (V94.3A) was success-fully accomplished in 2010. The system shows a similar potential as on the SGT5-2000E (V94.2). The highest delta gas turbine power output of about 16 percent has been measured at a Wet Compression mass flow of about 10.2 kg/s. In addition, the gas turbine’s efficiency has been increased by about two percent. The achievable maximum power output of up to 30 MW with Wet Compression is limited by a maximum water mass flow (two percent of the compressor inlet mass flow). However, not all sites can reach the full potential of Wet Compres-sion due to site-specific limitations that include generator/transformer limits, shaft limits, combustion instabilities, and special limiting hardware configurations. [1]

Operational Flexibility Upgrade

The Operational Flexibility Upgrade (OFU) is an integra-tion of proven products that optimize the individual pow-er plant performance and increasing operational flexibili-ty within a long-term service agreement. The Operational Flexibility Upgrade combines proven technologies that include improved blade and vane design and enhanced combustion technology.

The Operational Flexibility Upgrade includes a turbine performance upgrade that modifies key turbine compo-nents and hot gas parts, allowing for a significant firing temperature increase. This modernization has been designed to generate a power increase, an improvement in heat rate, and additional exhaust energy. These results are achieved through the application of new coat-ings on the turbine blades and vanes and a reduction in cooling air in the hot gas path. In addition to the perfor-mance increase, the Operational Flexibility Upgrade al-lows for a maintenance interval extension to 33MAC. This results in increased availability of the entire plant, because the major outage is only performed every 33,000 EOH.

The following benefits can be achieved:■■ Up to 13 MW gas turbine power output increase

in simple cycle operation■■ Up to 21 MW combined cycle power output

improvement (1x1)■■ Up to 0.4 percentage points combined cycle

efficiency improvement■■ Potential reduction of NOX emission

down to 15 ppm

The Operational Flexibility Upgrade optimizes upgrade combinations and provides the best unit-specific balance of plant solutions, with the maximum possible perfor-mance increase and enhanced maintenance intervals as part of a long-term program contract extension. The Operational Flexibility Upgrade is the ticket to a flexible operating domain that extends the original equipment manufacturer coverage beyond 100,000 EOH and can be implemented at any outage during the long-term service agreement program. The Operational Flexibility Upgrade will typically be implemented at the 100,000 EOH outage.

Fig. 10: Wet Compression spider nozzle Fig. 11: Schematic illustration of the Operational Flexibility Upgrade

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Conclusion

Recent improvements in turbine technology have pro-duced major benefits, including increased flexibility and improved reliability and availability. All of these benefits make a gas turbine modernization project attractive and highly beneficial for aging power plants. In addition, short lead times for the realization of these moderniza-tions and upgrades – when compared with new installa-tion projects – enable a response to near-term capacity needs.

The upgrade solutions described above – the Power Limit Increase, Wet Compression, and Operation Flexibility Upgrade packages, among others – represent only a small part of the solutions provided for the Siemens gas turbine fleet today, and reflect the market’s demand for enhanced capability and flexibility. Many more solutions are available, and they can be combined to address the customer’s need for not only improved flexibility but also high reliability and availability with reasonable mainte-nance costs and reduced emissions.

Each upgrade step is verified with various test methods to ensure reliable engine operation. The proven product development process and the integrated validation con-cepts demonstrate an extensive quality assurance model for our customers. As part of this continuous research and development process, Siemens is committed to delivering excellent solutions that are highly beneficial for the power generation industry.

References[1] Beiler, J. D. “High Efficient Peak Power on Demand.” Publication, Siemens AG, 2011.

[2] Sorgenfrey, Chr. “Beneficial lifetime extension of SGT5-2000E gas turbines through modernization.” Publication, Siemens AG, 2011.

Permission for useThe content of this paper is copyrighted by Siemens and is licensed to PennWell for publication and distribution only. Any inquiries regarding permission to use the con-tent of this paper, in whole or in part, for any purpose must be addressed to Siemens directly.

Disclaimer These documents contain forward-looking statements and information – that is, statements related to future, not past, events. These statements may be identified either orally or in writing by words as “expects”, “antici-pates”, “intends”, “plans”, “believes”, “seeks”, “estimates”, “will” or words of similar meaning. Such statements are based on our current expectations and certain assump-tions, and are, therefore, subject to certain risks and uncertainties. A variety of factors, many of which are beyond Siemens’ control, affect its operations, perfor-mance, business strategy and results and could cause the actual results, performance or achievements of Siemens worldwide to be materially different from any future results, performance or achievements that may be ex-pressed or implied by such forward-looking statements. For us, particular uncertainties arise, among others, from changes in general economic and business conditions, changes in currency exchange rates and interest rates, introduction of competing products or technologies by other companies, lack of acceptance of new products or services by customers targeted by Siemens worldwide, changes in business strategy and various other factors. More detailed information about certain of these factors is contained in Siemens’ filings with the SEC, which are available on the Siemens website, www.siemens.com and on the SEC’s website, www.sec.gov. Should one or more of these risks or un certainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in the relevant forward-looking statement as anticipated, believed, estimated, expected, intended, planned or projected. Siemens does not intend or assume any obligation to update or revise these forward-looking statements in light of developments which differ from those anticipated. Trademarks mentioned in these documents are the property of Siemens AG, its affiliates or their respective owners.

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Subject to change without prior notice. The information in this document contains general descriptions of the technical options available, which may not apply in all cases. The required technical options should therefore be specified in the contract.