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Electrohydraulic Drive System EHC-A

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Your Professional Partner for Electrohydraulic Drive Systems.With over 8,000 employees worldwide, HYDAC is one of the leading suppliers of fluid technology, hydraulic and electronic equipment.

Our wide range of products, combined with our expertise in development, manufacturing, sales and service enables the thermal power industry worldwide to overcome the most diverse challenges with the aid of electrohydraulic drive systems.

Global yet local.With over 50 overseas subsidiaries and more than 500 sales and service partners, HYDAC is your reliable partner worldwide.

System solutions. One supplier. One contact.Wherever you need us, we are there to help you find the most effective solution – for almost every application, from components to a complete system.

Worldwide specifications and approvals.

Slam-shut valve to protect against turbine overspeed

HP bypass station

LP bypass station

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Functional safety in the water/steam circuitProcess technology systems in the power plant must be operated “safely” because they pose a considerable potential hazard to human health and the environment and can cause damage.

When developing appropriate protection systems, the focus must centre on parts of the control which are relevant to the safety of the machine.

This is particularly relevant for control valves and their drives which have an overlaid safety function. The requirement for a control valve with a safety function and the device for monitoring the steam condition are, amongst other things, described in EN ISO 4126-5 and TRD421.

The objective of the regulations is to detect a failure safely and to trigger a safety function.

Description and advantagesBy using electrohydraulic systems, movements can be controlled. Compared with other drive types, electrohydraulic drives are differentiated by:

High power density

Low moments of inertia

High dynamic response

Compact size

High degree of accuracy

High level of reliability and long life

Integrated linear measurement

Electrohydraulic Drive System EHC-A

Applications

Water/steam circuit

In the water/steam circuit, pressure and temperature are finely adjusted and controlled using steam valves to correspond with the requirements of the systems further downstream, for example the turbine. By using hydraulic actuators high quality control and the maximum dynamic response are achieved.

Note: The information in this brochure relates to the operating conditions and applications described. For applications or operating conditions not described, please contact the relevant technical department. Subject to technical modifications.

Minimum flow control valve

Feed water flow control valve

Level control valve

Back-up steam control valve

HD injection valve

IS injection valve

HP bypass station

IS relief valve

LP bypass station

Condensate control valve

Turbine shut-off valve

Turbine inlet valve

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Preferred ranges

Electrohydraulic Drive System EHC-A 50 63 80 100 125 140 160 180 200 220 250Piston diameter D mm 50 63 80 100 125 140 160 180 200 220 250

Rod diameter d mm 25 28 36 45 50 56 63 70 80 90 100

Reduced piston diameter Dr mm 25 28 36 45 50 56 63 70 80 90 100

Cylinder stroke max. hz mm 50 63 80 100 125 140 160 180 200 220 250

Maximum pressure Pmax bar 250 250 250 250 250 250 250 250 250 250 250

Working pressure min. Pa bar 100 100 100 100 100 100 100 100 100 100 100

Static force from Working pressure min. FkOil (Pa) kN 14.7 25.0 40.1 62.6 103.1 129.3 169.9 216.0 263.9 316.5 412.3

Spring force min. F1 kN 7.4 12.5 20.0 31.3 51.5 64.7 84.9 108.0 131.9 158.3 206.2

Spring force max. F2 kN 11.0 18.8 30.1 47.0 77.3 97.0 127.4 162.0 197.9 237.4 309.3

Counterforce from system (75 % of F1) FSteam kN 5.5 9.4 15.0 23.5 38.7 48.5 63.7 81.0 99.0 118.7 154.6

Model code

EHC-A – XXX – X – X – X – X

Electro Hydraulic Control Actuator

Piston diameter XXX = mm

Cylinder type S = Double rod cylinder (synchronizing) D = Single rod cylinder (differential)

Type of spring D = Disc spring S = Spiral spring W = Without spring

Direction of movementbwith spring assistance E = Extension R = Retraction

Measurement technology W = Linear measurement system O = Optical/mechanical position indicator E = Limit switch P = Pressure measurement ( X) = Redundant version possible

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Electrohydraulic Drive System EHC-A 50 63 80 100 125 140 160 180 200 220 250Piston diameter D mm 50 63 80 100 125 140 160 180 200 220 250

Rod diameter d mm 25 28 36 45 50 56 63 70 80 90 100

Reduced piston diameter Dr mm 25 28 36 45 50 56 63 70 80 90 100

Cylinder stroke max. hz mm 50 63 80 100 125 140 160 180 200 220 250

Maximum pressure Pmax bar 250 250 250 250 250 250 250 250 250 250 250

Working pressure min. Pa bar 100 100 100 100 100 100 100 100 100 100 100

Static force from Working pressure min. FkOil (Pa) kN 14.7 25.0 40.1 62.6 103.1 129.3 169.9 216.0 263.9 316.5 412.3

Spring force min. F1 kN 7.4 12.5 20.0 31.3 51.5 64.7 84.9 108.0 131.9 158.3 206.2

Spring force max. F2 kN 11.0 18.8 30.1 47.0 77.3 97.0 127.4 162.0 197.9 237.4 309.3

Counterforce from system (75 % of F1) FSteam kN 5.5 9.4 15.0 23.5 38.7 48.5 63.7 81.0 99.0 118.7 154.6

Technical DetailsNominal pressure 160 - 250 barOperating fluids ISO VG 32, ISO VG 46, Mineral oil to DIN 51 524, HFD-U

HFD-R fire-resistant ISO 6743-4 – others on requestTemperature range of environment -5 °C to +60 °C, option -20 °C to +80 °COperating temperature optimum +40 to +50 °CAtmosphere Dusty industrial environment, potentially explosive according to ATEX Directive (optional)Relative humidity up to 90 %

Electrical dataSupply voltage 24 V DC, 230 V 50/60 Hz ACVoltage tolerance up to +15 % / -15 %Nominal current of coil 0.8 A for 24 V DC (TRD system), 1.2 A for 24 V DC (standard coil)Protection class IP65 (Standard), ExII 2G Eex d IIC T4 (Atex)Nominal current for positioning module < 100 mATarget position 0-100 % 4 - 20 mAActual position 0-100 % 4 - 20 mA

PositioningPositioning accuracy < 1 %Repeatability < 0.1 %Hysteresis < 0.1 %

Actuating timesControl operation 3 s - 60 sControlled Open / Close 1 s - 30 sSafety stroke Open / Close 0.1 s - 1.5 s

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Function diagram

Option: Safety and Function Module

The modular electrohydraulic safety controls EHC-S from HYDAC satisfy the requirements of IEC 61508 and IEC 61511.

EHC-S 1oo1Applications in so-called enable circuits

EHC-S 1oo3For ball valve applications in water/steam circuits

EHC-S 2oo3Applications in turbine controls and on process safety valves

Control module EHC-D Hydraulic control EHC-S Hydraulic cylinder EHC-A

Enable

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Control program

Input scaling

Input scaling

Control function

Control adaption

Feedback

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StartHand +Hand -

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Other versions on request.

EHC-MFunction module for steam valve controls

EHC-UPower unit for oil supply in turbine controls

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System Expertise with First-Rate Service Network: Local Availability – Worldwide.User accessoriesHYDAC offers a comprehensive and proven range of condition monitoring products, components and systems designed for fluid conditioning and monitoring as well as for technical cleanliness of components.

Condition monitoring Contamination sensor CS 2000To monitor the essential fluid parameters in turbine hydraulics online, HYDAC has developed an extensive fluid monitoring range which makes a significant contribution to the safe operation of both the turbine hydraulics and lubrication.

FAM dewatering unit On lubrication oil systems of steam turbines, particularly high levels of unwelcome process steam and water enter the oil circuit.

This results in substantially increased fluid ageing and limited lubrication. By using FAM dewatering and filtration units continuously during system operation, integrated conditioning of the lubrication media is assured.

Degassing unit IXUWhen hydraulic fluids based on phosphate esters are used, it is essential to condition the fluids (also during system operation).

HYDAC offers an extensive range of ion- exchange conditioning products (IXU).

Stat-Free filter elementsThe operation of modern power plant hydraulics and lubrication systems with zinc-free fluids gives rise to risks of electrostatic charging of the oils (especially via the filter elements). Uncontrollable voltage flashovers, formation of sludge and varnish as well as rapid oil ageing are the result.

HYDAC Stat-Free filter element technology prevents these unwelcome side-effects and increases the safety of the system for the operator.

NEW

HYDAC Headquarters

HYDAC Companies

HYDAC Sales and Service Partners

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Global Presence. Local Expertise. www.hydac.com

Industriegebiet 66280 Sulzbach/Saar Germany

Tel.: +49 6897 509-01 Fax: +49 6897 509-577

E-mail: info@hydac.com Internet: www.hydac.com

Head Office HYDAC SYSTEM GMBH

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