Earthing of contact lines – automatizised by use of Sicat AESTranslation of elektrische Bahnen, 111 (2013) issue 3, 172-184

Sicat® AES is a Siemens developed and produced auto-matisized earthing system for contact lines to create a hazard-free safety status. Applications of the system are emergency recovery tasks in electrified railway tunnels for mainline and service and maintenance halls for electri-

cally powered railway vehicles. The system was developed further and complies with the security requirements accor-ding to the current standards. The system can advantage-ously used for light rail systems.

siemens.com/rail-electrification

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Content

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. The Sicat AES automatic earthing system concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1 Development history ...................................................................................................................... 3

2.2 Requirements ................................................................................................................................. 3

2.2.1 Requirements according to the TSI Safety in Railway Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2.2 Requirements of the Federal Railway Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.2.3 Regulation for a common method of evaluating and assessing risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.3 Purpose and basic function ............................................................................................................ 4

2.4 Safety Case ..................................................................................................................................... 5

2.5 Adaptations to operators‘ and system requirements ...................................................................... 5

2.6 Benefits for the user ....................................................................................................................... 6

3. Control and operating components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Control center ................................................................................................................................ 6

3.2 Substations ..................................................................................................................................... 6

3.3 Control panels ................................................................................................................................ 7

4. Equipment for the overhead contact line. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.1 Earthing disconnector with entry monitor ..................................................................................... 7

4.1.1 Series 8WL6144 disconnectors and earthing disconnectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.1.2 Series 8WL6134 disconnectors and earthing disconnectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.1.3 Sicat DMS position and entry monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2 Isolator operating tube guidance and setting ................................................................................ 9

4.3 Motor operated mechanism ........................................................................................................... 9

4.4 Voltmeter ....................................................................................................................................... 9

4.5 Work boundary warning signs ........................................................................................................ 10

5. Application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5.1 Emergency earthing in DB AG tunnels ........................................................................................... 11

5.2 Automatic earthing in halls ............................................................................................................ 11

5.3 Automatic earthing for maintenance and emergencies ................................................................. 11

5.4 Automatic earthing for DC mass transit systems ............................................................................ 12

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1. Introduction

Modern railway systems require up-to-date infrastructu-res and vehicles in order to shorten transport and jour-ney times, improve transport services, and consequently enhance the attractiveness of rail-bound transport. In a densely populated country like Germany, this means that a greater proportion of the lines has to pass through tunnels in order to shorten distances and travel times.

When it comes to building new lines and upgrading exis-ting ones, top priority is given to safety and the reduction of risks in case of emergencies.

To reduce such risks, Siemens AG has developed Sicat AES, an automatic earthing system for contact lines which per-forms all the earthing and short-circuiting functions auto-matically. Whenever emergency situations occur in tun-nels, in railway station areas, during maintenance work on defined line sections or on tracks in maintenance halls, Sicat AES de-energizes the overhead contact line system under coordination from the control center, creates a safe state by earthing the contact line, and displays this state.

2. The Sicat AES automatic earthing system concept

2.1 Development history

Deutsche Bahn (DB AG) and VA TECH SAT GmbH - now part of Siemens AG - started to develop an overhead line voltage testing and automatic earthing system (OLSP) in 1998. This development work was prompted by the fact that third parties had taken over rescue duties in railway tunnels from DB AG‘s own rescue trains.

The Federal Railway Authority (EBA) guideline „Fire and disaster protection requirements in railway tunnels“ [1]requires the infrastructure operator to make sure that „the overhead contact line is de-energized and earthed by the time the rescue services arrive“. However, it is not possi-ble for DB AG‘s emergency managers to complete this task within the maximum intervention time of 30 minutes allo-wed in the guideline „Fire and disaster protection in railway tunnels“ [2]. But use of the OLSP system enables this requi-rement to be met because OLSP eliminates the time-con-suming, double-ended earthing with earthing equipment.

The OLSP was used for the first time in 1999 in a pilot pro-ject at the Frankfurt Kreuz and in the Kelsterbach Tunnel on the Cologne–Rhine/Main high-speed line. After the suc-cessful trials, OLSP was installed in all the tunnel systems on the Cologne–Rhine/Main high-speed line. Since then VA TECH SAT GmbH and, since the takeover, Siemens AG have supplied around 50 OLSP systems for new and existing tun-nels.

Approval of the control, monitoring and telecontrol sys-tems is based on the standards VDE 0105 [3] and require-ment category 3 according to DIN V 19250 [4]. The latter requirement was replaced by EN 6954-1 [5], category 3, in 2010. Taking into account the Machinery Directive and the

announcement of its withdrawal on December 31, 2011, the revision and further development of the OLSP system components began in 2012. The product name was also changed to Sicat AES. This is the further developed system that is available today.

2.2 Requirements

2.2.1 Requirements according to the TSI Safety in Railway Tunnels

The technical specification „Safety in Railway Tunnels“ (TSI SRT [6]) applies to interoperable conventional and high-speed routes. It was ratified by the European Union in 2007. This specification defines measures for all subsystems, such as infrastructure and energy, for safety in railway tunnels. It specifies measures for reducing risks in tunnels which are not already covered by general safety standards for rail-ways. The TSI applies to both new tunnel systems and sys-tems that are to be modernized or upgraded in tunnels that are at least one kilometer long. Tunnels that are over 20 km long require a separate safety assessment, for example the Gotthard Base Tunnel in Switzerland which is currently under construction. In tunnels more than five kilometers long, the overhead contact line must be subdivided into switching sections or circuit groups if the signaling allows more than one train on each track in the tunnel simultane-ously. The number of switches in the tunnel should be kept to a minimum.

When the rescue services arrive, they cannot know the state of the overhead contact line, which is why it is neces-sary for the overhead contact line to be switched off and earthed. This must be ensured by the infrastructure opera-tor before the tunnel or a section thereof is entered. The responsibilities for this must be agreed between the infra-structure operator and the rescue services and defined in an emergency plan. The equipment required for earthing the overhead contact line must be located at all the sec-tioning points between the circuit groups. It is irrelevant whether the earthing equipment is actuated manually by the rescue services or by remote control from a permanent installation.

2.2.2 Requirements of the Federal Railway Authority

The guideline „Fire and disaster protection requirements for the construction and operation of railway tunnels“ [1]of the Federal Railway Authority (EBA) describes the type and extent of structural and operational measures required in Germany to make rescue and self rescue possible in rail-way tunnels. The requirements of TSI SRT for interoperable lines in the currently valid 2008 edition of this guideline were adopted into national law.

In contrast to the TSI SRT, this guideline shall be applied to tunnels longer than 500 m, taking the principle of propor-tionality into account. Tunnels in light rail transit systems are exempted from this requirement.

Accordingly, the infrastructure operator, for example DB AG, must ensure that the overhead contact line, as well as any other existing live lines, are switched off and earthed as quickly as possible. The EBA guideline requires a vol-tage testing and automatic earthing system for overhead

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lines to be installed at the tunnel entrances and the emer-gency exits, something which is not covered in the TSI RST. The OLSP must inform the rescue services about the state of the overhead contact line and earth and short-circuit it manually in the event of malfunctions. The minimum requirements concerning the reliability of the display of the earthing state by the OLSP is specified by reference to DIN VDE 0105, Part 100, Point 6.2.102, [3].

2.2.3 Regulation for a common method of evaluating and assessing risks

Since July 1, 2012, railway undertakings and infrastructure managers have been obligated to apply „Commission Regu-lation (EC) No. 352/2009 of 24 April 2009 on the adoption of a common safety method on risk evaluation and assess-ment as referred to in Article 6(3)(a) of Directive 2004/49/EC“ to the safety-related installations that they operate [7]. This regulation is referred to by its short form CSM-VO (Common Safety Methods), and is based on EN 50126 [8]. The objective of the regulation is to harmonize the risk management and thus enable or ensure the mutual recognition of results. The regulation is not required to be applied to underground railways, tramways and other mass transit and regional railways. The regulation specifies the basic requirements for a risk management process. This comprises the following necessary activities: y definition of the system, y risk assessment, y identification of the resulting safety requirements, y demonstration of the compliance of the system with the identified requirements, and

y management of all hazards and the associated safety measures.

Three risk acceptance principles are to be used for the pur-pose of risk evaluation and assessment.

By applying the recognized rules of engineering, it has been possible to cover the identified hazards within the

scope of Sicat AES. A hazardous state, in which a person is endangered, always exists when the overhead contact line is neither disconnected nor earthed but the system indica-tes that it is in a safe state, i.e. that the overhead contact line has been disconnected, de-energized and earthed. This state results from a combination of several subhazards, as shown in Figure 1.

IEC 61508 [9] and the industry-specific standards EN 50128 [10] and EN 50129 [11] were used as the basis for the elec-tronic components of the automatic earthing system in order to meet the requirements of various national mar-kets. Sicat AES is intended to be used in applications with safety integrity requirements up to safety integrity level SIL 2.

2.3 Purpose and basic function

The Sicat AES earthing system performs the earthing step by step and verifies each state against the five safety rules according to DIN EN 50110 [12] for work in the area of an overhead contact line system. These are: y disconnect the overhead contact line, y secure it against reconnection, y verify safe isolation from the supply, y earth and short-circuit, and y cordon off adjacent, live system sections by signposting the boundaries of the work zone.

The state of the overhead contact line is monitored conti-nuously. The earthed state of the contact line is indicated at the work boundaries and access points, for example at the tunnel entrances.

Figure 2 shows the system for disconnecting the overhead contact line in the normal operating state. The central sta-tion of Sicat AES is networked with the associated substa-

SCADA

Tunnel

Track 1

Track 2

Central station

Communication medium acc. to IEC 60870-5-101/-104

Substation without local control equipment

Control panel

Work boundary

Emergency exit1

23

4

Substation withlocal control equipment

Control panel

Substation with local control equipment

Control panel

Work boundary

Work boundary

Work boundary

Figure 2: Sicat AES system concept; diagram showing the dis-connection function of the overhead contact line system in the operating state.1 – Disconnector / switch disconnector to disconnect the overhead contact line2 – Voltage transformer / isolation amplifier3 – Earthing disconnector / earthing switch disconnector4 – Work boundary warning sign with integrated additional notice „Work boundary“, mechanically or electrically actuated

Figure 1: Hazard analysis of the automatic earthing of over-head contact lines.

AND

Undesirable event:Persons endangered

Overheadcontact line not

disconnected

DISCONNECT

Overheadcontact linenot earthed

EARTH

System indicatesincorrectly the safe

state „de-energized“

OR OR

System indicatesincorrectly the safe

state „earthed“

Voltage stateincorrectly

detected / recorded

ERK_SPG

Voltage stateincorrectlytransmittedor processed

FWA_SPG

Voltage stateincorrectlydisplayed

ANZ_SPG

Earthing stateincorrectly

detected / recorded

ERK_ERDG

Earthing stateincorrectlytransmittedor processed

FWA_ERDG

Earthing stateincorrectlydisplayed

ANZ_ERDG

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tions and coordinates the earthing system. It is connected to the SCADA control center and transmits the states of the earthings. In the event of a malfunction, the control center commands the Sicat AES control center to start the auto-matic earthing system. Alternatively, the earthing systems can be operated from the local substations located near the tunnel entrances and emergency exits or the access points to the protected areas. There are substations with and wit-hout local control equipment. Substations with local con-trol equipment include the components for actuating the disconnectors and/or earthing disconnectors. The control panels include at least displays for the voltage state of the overhead contact line and the emergency actions of the rescue services.

The overhead contact line equipment includes: y all switches to disconnect the circuit group, y voltmeters, y earthing disconnectors or make-proof earthing discon-nectors, and

y warning signs to indicate the boundaries of the work zone.

The components are required for compliance with the five safety rules and are part of Sicat AES.

Earthing switches connect the overhead contact line to the negative return by a permanently installed cable, and thus short circuit the overhead contact line. The earthing swit-ches used are equipped with an entry monitor, which con-tinually monitors the end position of the disconnector.

Figure 3 is a diagram of a section in a disconnected, safe switching state in the event of a fault. The circuit breaker has been opened and secured against reconnection. After the voltage test showed that all line voltages were below the threshold value, the earthing switches were closed and the work boundary sign activated. The control panels then showed clearance for access by the rescue services.

2.4 Safety Case

Safety cases were prepared for the previously supplied sys-tems according to the relevant version of the standards, which continue to remain valid for existing systems. The functional safety case for the instrumentation and con-trol components of Sicat AES for new systems aspires to safety integrity level SIL 2 according to EN 50128 [10] and EN 50129 [11]. The safety case will be completed in the summer of 2013. The safety case for the earthing switch verified the short-circuit current capability up to 40 kA and the safe functioning of the newly designed entry monitor via rotary encoders. The safety plan also includes the deve-lopment procedure, together with all the work planned and performed, such as the architecture and detailed drafts for hardware and software, as well as the commissioning, vali-dation, and maintenance specifications. The type, scope and contents of the analyses and documents, as well as the methods used, meet the requirements of safety level SIL 1. For the motor operated mechanism which electrically actuates the earthing switch and for the voltmeters, it was only necessary to verify compliance with the standards and specific operator‘s requirements.

2.5 Adaptations to operators‘ and system requirements

Sicat AES can be adapted to meet diverse system and ope-rator-specific requirements. The systems can be used for the contact lines of AC and DC railways, for which the over-head contact line components are available. Requirements and technologies introduced by rail operators can be met with special components, such as switch disconnectors. A hazard and risk analysis must be performed specifically for this purpose if required.

In the case of applications with local limitation, such as maintenance and service halls, depots and washing tracks, the system layout can be simplified by combining the cen-tral and substations together, as shown in Figure 2.

The responsibility and scope of functions of Sicat AES can be adapted to meet requirements. It is often required that the responsibility for disconnecting the overhead contact line rest with the infrastructure operator, so that the tun-nel can be cleared depending on the emergency situation involving vehicles. In this case, the automatic earthing sys-tem retains the tasks of continuous voltage testing and monitoring, earthing and short circuiting, and cordoning off adjacent live systems.

The appearance, structure and function of the control panel are often designed differently to meet the operator‘s requests. This applies to various requirements for safe dis-plays, local operation and the automatic earthing system. Before clearance is given for the rescue operation to begin under the five safety rules, there is frequently a require-ment for an additional protective measure must be taken, such as turning a key switch to prevent inadvertent recon-nection of the power supply. This gives the leader of a res-cue team the opportunity of taking charge of the earthing state for the duration of the operation.

SCADA

Tunnel

Track 1

Track 2

Central station

Communication medium acc. to IEC 60870-5-101/-104

Substation without local control equipment

Control panel

Work boundary

Emergency exit1

23

4

Substation withlocal control equipment

Control panel

Substation with local control equipment

Control panel

Work boundary

Work boundary

Work boundary

Rescue team Rescue team

Rescue team

Figure 3: Sicat AES system concept; diagram showing the dis-connection function of the overhead contact line system in the disconnected and safe state.

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2.6 Benefits for the user

Automatic earthing systems, such as the Sicat AES, are primarily used to avert hazards and reduce risks in tun-nels, where they also form part of the self-rescue measu-res. They ensure that rescue services can start their work quickly. Automatic earthing runs reliably in maintenance halls and saves time, which makes it cost effective.

The user benefits from: y high reliability, y safety certified according to the state of the art, y straightforward operation, y flexibility in adapting to customer requirements, y use of service-tested components, y clear display of the state of the system on illuminated panels and operator controls,

y low maintenance costs, and y a long lifetime.

To meet field service conditions and requirements, the user benefits and reliability can be increased by: y redundant communication channels between the system components,

y a key system to lock the safe state, y an uninterruptible power supply (UPS) to maintain func-tionality in the event of a power outage, and

y self-diagnosis and monitoring.

3. Control and operating compo-nents

3.1 Control center

The control center is the heart of the Sicat AES automatic earthing system. All communication to the individual sub-stations goes through the control center. The control cen-ter communicates with the responsible SCADA control cen-ter and administers the individual substations, including safety-related signals. The substation is located either in a trackside equipment house or an electronic interlocking (SSI). The SICAM AK ACP automation component is used in the control center (Figure 4). It meets all communica-tion and redundancy requirements and has system-wide functionality according to IEC 60870-5-101/104 [13], [14]. All open-loop and closed-loop control tasks are performed according to IEC 61131-3 [15]. The safety applications can be implemented according to IEC 61508. The boards in all the automation components used in the SICAM 1703 can be replaced without using an engineering tool. The data are stored on flash cards. Used together with the compre-hensive remote diagnostic capabilities, this keeps downti-mes low.

Visualized, full local operation (HMI) is integrated into the Sicat AES control center, which can be used locally for repair work. Full local operation visualizes and logs all pro-cess states, events, faults and malfunctions. These can be archived and evaluated in PDF files.

3.2 Substations

Substations at the tunnel entrances and other important positions (Figure 5) communicate directly with the control center, pass information on to it, and process all signals and commands. The substations no only show the rescue services the state of the overhead contact line in the line section, they can also remotely control other substations, actuate all the earthing switches in a tunnel system and thus earth them in the event of faults. When a substation initiates an emergency earthing, the control center coordi-nates all the substations in the system, and also trips emer-gency earthings there. In order to obtain the most accurate information about the state of the system, the data chan-nels between the substations and control center are under continuous electronic monitoring. As an option, they can be designed redundantly if necessary and laid in fire and destruction-proof cable routes.

The SICAM AK ACP or SICAM TM ACP (Figure 6) automation components are used for the automation in both the sub-stations and the control center. This means that the same automation components are used throughout, which mini-mizes the stocks of spare parts.

The substations have or do not have local control equip-ment, depending on their location. The stations at the tun-nel entrances usually have local control equipment. The stations without local control equipment are to be found at emergency exits, for example. The substations display the state of the overhead contact line systems in the tunnel and are used by rescue teams as a local possibility of emer-gency earthing. Substations with local control equipment Figure 4: Sicat AES – control center.

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can control the switching elements for disconnecting and earthing the contact line and process measured voltage values in their respectively assigned section. Substations without local control equipment do not have a direct pro-cess connection.

3.3 Control panels

The control panels (Figure 7) are an important part of the types of substations. The states of the overhead contact line systems in the tunnel are indicated by multiple LED segment displays: RED / GREEN / YELLOW are displayed. Rescue services can trip the automatic earthing by pressing a button or turning a key switch to make conditions safe for rescue in the assigned section. The control panel can also be mounted in a separate housing.

4. Equipment for the overhead con-tact line

4.1 Earthing disconnector with entry moni-tor

4.1.1 Series 8WL6144 disconnectors and earthing disconnectors

Series 8WL6144 disconnectors and earthing disconnec-tors (Figure 8) constitute outdoor switchgear according to DIN EN 50152-2 [16], and have been released as further developments of the proven series 8WL6127 for AC up to 16.7 and 50/60 Hz, rated voltages up to 25 kV and rated currents up to 2.5 kA. The insulated holder has been impro-ved, the weight reduced, and maintenance costs have been reduced by the use of silver-graphite contacts with long-lasting, self-lubricating properties. Series 8WL6144 disconnectors can be designed as standard disconnec-tors without an earth contact (8WL6144-0), with an earth contact (8WL6144-1), or as an earthing disconnector (8WL6144-1A). All disconnectors can be equipped with the Sicat DMS (Disconnector Monitoring System) entry moni-tor. They are suitable for outdoor use and, above the mini-

mum requirements of the standard, have a 1.7 kA current carrying capacity for a maximum of 15 switch-off cycles. Arcing when the contact is broken prevents them being used in tunnels, halls or under contact lines. Earthing disconnectors can also be used in tunnels, provided that switch-on short-circuit strength is not required. This is also not needed technically because the disconnection of the system according to TSI SRT is a basic task of the infra-structure operator, thus making unintentional short-circu-iting of a live overhead contact line impossible in case of a necessary line closure.

Disconnectors can be used at one end to the negative

Figure 5: Sicat AES substation in the Günterscheid Tun-nel on the Cologne–Rhine/Main high-speed line.

Figure 6: Sicat AES safety-related controllers in the substations.1 – Central processing unit (ZBG-S)2 – Peripheral device for fire department, panel, UPS, etc. (EAB-S)3 – Peripheral device for evaluating and monitoring voltage transformers (SWB-S) 4 – Controller for earthing switches and position switches (MSB-S)

1 2 3 4

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return and as an earthing switch. The Austrian Federal Railways (ÖBB) equips its earthing switches with position arrows to give the rescue services an indication of the state of the contact line. Special earthing disconnectors are used in Germany for the purpose described, in which the insu-lator of the stationary contact is replaced by a steel or alu-minum construction. In the earthed state, it can be seen that the movable switching contact, and thus the overhead contact line, is short-circuited with the negative return.

4.1.2 Series 8WL6134 disconnectors and earthing disconnectors

Series 8WL6134 disconnectors and earthing disconnectors (Figure 9) constitute outdoor switchgear according to DIN EN 50123-4 (Category I) [17], and are released for voltages up to 3 kV DC and currents up to 4 kA. Since the end of 2011, the contacts have been provided with a silver-gra-phite coating to keep operational maintenance costs low.

The modular structure of the 8WL6134 disconnector series allows equipment options with line terminals on the sta-tionary contact with or without an earth contact (e.g. 8WL6134-4/-4A) or with line terminals on the movable con-tact with or without an earth contact (e.g. 8WL6144-2A). All versions can be fitted with the Sicat DMS entry monitor and can be used as an earthing switch disconnector by con-necting one end to the negative return.

4.1.3 Sicat DMS position and entry monitor

The Sicat DMS position and entry monitor (Figure 10) was released as a component for all Siemens AC and DC dis-connectors at the end of 2009. The position of the discon-nector is monitored by a rotary encoder mounted at earth potential, which detects the position of the moving switch contact by means of an axially aligned, mounted magnet. The 8WL6243, 8WL6244, 8WL6253 and 8WL6254 opera-

ted mechanisms with a permanent power supply have an interface for reading out the sensor information. Conse-quently, there is no need for an evaluation unit.

An entry monitor for SIL 1 according to EN 50128 and EN 50129 was developed at the end of 2011 for safety-related applications, such as entry monitoring of earthing swit-ches. The previous principle could not be retained and had to be replaced by a redundantly designed sensor. The unit which evaluates the position messages was separated from the control board of the operated mechanism and desig-ned as an external board (8WL6255-7A/-7B). The interfaces are floating contacts, with a selectable power supply of eit-her 24 V DC or 230 V AC. This facilitates the uniform design of the double message required for safe entry monitoring by many operators, such as DB AG and ÖBB.

The robust, contactless measuring principle that can be adapted to all types of disconnectors is a significant advan-

Figure 8: 8WL6144-0 disconnector 25 kV AC without earth contact.

Figure 7: Sicat AES control panels.

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tage. As the path of the movable switching contact is spe-cified by the device version for 3 kV DC and 25 kV AC, the threshold values for ON, NOT ON, OFF and NOT OFF mes-sages are fixed. Tolerances in the entry during operation and limits required to secure the electrical properties, such as minimum air clearances and short-circuit strength, are taken into account. A learn function compensates for the mounting tolerances of the sensor and magnet during commissioning. In contrast to the previous sensor and monitoring functions, the ON and OFF messages are moni-tored by one sensor.A unit for evaluating the measured voltage value is integra-ted in the 8WL6255-7A/-7 control unit, which can be used optionally. Similarly to the entry monitoring, the voltage state of the overhead contact line is output as a double message via the floating contacts.

4.2 Isolator operating tube guidance and setting

Disconnectors and earthing switches are actuated by a motor drive via an isolator operating tube (Figure 11). On account of the remote control, this type of drive is also referred to as a motor operated mechanism. The design and materials used, such as glass-reinforced plastic or steel tube, are customer-specific. The isolator operating tube guidance should transmit the force initiated by the motor drive as directly as possible to the switch without defor-ming the tube. Bent tubes are not used for this reason.

With previous designs of the isolator operating tube, the fine setting of the switch contact sets was often time-con-suming. A 8WL6229-0 steel tube setting sleeve was deve-loped and released for isolator operating tubes in 2011 for this purpose. It is primarily used in the inclined tube of the operating tube and also has a fine thread to facilitate the required setting of the contacts sets.

4.3 Motor operated mechanism

The Sicat AES earthing system requires remote-controlled motor operated mechanisms to open and close the discon-nectors and earthing switches (Figure 12). Manual ope-ration is possible if the drive voltage is lost. The standard stroke of the 8WL6243/44/53/54 series motor operated mechanisms is 200 mm. Its switching force is at least 4 kN with all conventional control and motor voltages, such as 24 V DC to 250 V DC and 110 V AC to 230 V AC. The actu-ating force has been adapted to the force-distance curve and reaches its highest values in the end positions. The operated mechanisms are locked in their end positions. This ensures that influencing forces, such as weights and short-circuit forces, cannot change the entry positions of the switch contacts. The control components required for the Sicat DMS entry monitor and the voltmeter can be inte-grated directly into the operated mechanism.

4.4 Voltmeter

Resin-encapsulated voltage transformers according to EN 60044-2 [18] are used for the continuous measurement of the line voltage in outdoor applications for AC railways. The function of the voltmeter is monitored during normal

Figure 9: 8WL6134-4 disconnector 3 kV DC without earth contact.

Figure 10: 8WL6144-0 Sicat DMS position message and entry monitor.

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operation by means of a transformed secondary voltage corresponding to the line voltage.

For DC railway applications, the voltage is monitored by the Sitras® PRO DC protective unit and controller. The Sitras Pro BA DC buffer amplifier supplies an electric voltage propor-tional to the line voltage or such a current. The voltage sig-nal of the section feed outputs can be tapped, especially for DC systems with short distances between power sub-stations.

4.5 Work boundary warning signs

Work boundary warning signs and limit notices for rescue services indicate the protected contact line section and warn of live adjacent sections. These are essential because, when an automatic earthing system is used, the usual „visi-ble earthing and cordoning off“ created by hooking in the earthing poles is not used. The warning signs are switched on if there actually are work boundaries or rescue limits. If adjacent rescue sections overlap, the warning signs can be actuated separately from the earthing switches. Purely

mechanical and electrical LED warning signs are used. The latter are primarily used in tunnel sections because they make the rescue limits safely visible even without extrane-ous light and under poor visibility conditions. The warning signs used comply with DIN 4844-1 and GUV-V A8 [19], [20]. Section 7 of GUV-V A8 defines the size of the warning sign by the edge length according to the distance at which it has to be legible. The distance at which it has to be legi-ble depends on whether the line is single or double-track, the location of the sign, and the escape routes. A typical distance is 12 meters. The Common Safety Methods Regu-lation must be complied with for newly developed elec-tric warning signs, which has an effect on the control and checkback signal.

The warning notice and symbols used can be adapted to country and operator-specific rules. As the term „work boundary“ in tunnel systems is not adequately defined, alternative labels such as „rescue limit“ are to be preferred in order to avoid misinterpretations, such as confusion with safe working on overhead contact line systems.

Figure 11: Isolator operating tube and guide on lattice mast with 8WL6229-0 setting sleeve for fine setting in the inclined tube.1 – Setting sleeve Figure 12: 8WL6253/54 series operated mechanism.

View A

View A

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5. Application examples

5.1 Emergency earthing in DB AG tunnels

DB AG described the technical implementation of the earthing requirements in the event of emergencies in tun-nels according to TSI SRT [6] and the EBA in the guideline „Fire and disaster protection requirements for the construc-tion and operation of railway tunnels“. In contrast to the basic Sicat AES concept (Figure 2), the central switching stations switch off the overhead contact line and lock the feeder circuit breaker. In an emergency, the central swit-ching stations start the automatic earthing immediately after alarming the rescue services, so that a safe state is created as quickly as possibly before the rescue services arrive. The condition for using automatic earthing is that the responsible rescue personnel have been trained, irres-pective of any training in traction system earthing.

Only DB AG, with the consent of the on-scene rescue servi-ces coordinator, may remove the earthing and resume rail services. The overhead contact line equipment, arrange-ment and switching of control components and interfaces are included in the drawings of Ebs 15.20.01 ff. of DB AG, and approved by the EBA.

The largest projects were the supply of the complete OLSP equipment on the high-speed lines Cologne–Rhine/Main,

which has 18 control centers and 70 substations, and Nuremberg–Ingolstadt, which has eight control centers and 48 substations. Further OLSP systems will be brought into operation on the Leipzig–Erfurt–Nuremberg high-speed line (project VDE 8).

5.2 Automatic earthing in halls

In workshops and maintenance halls, the automatic earthing system switches off the voltage (even in case of multiple voltage systems) to individual tracks and groups of tracks, verifies safe isolation from the supply, and earths and short-circuits the affected overhead contact lines over the tracks in the hall. The automatic sequence ensures safety according to the five safety rules and saves time. Multiple voltage systems have multiple interfaces and therefore require a more complicated configuration. After the automatic earthing has detected the safe state, it sig-nals the safe state and releases the work zone near the overhead contact line that is no longer live, for example an overhead contact rail. This state is blocked with autho-rization locking, for example key switches, until all work is finished and the work zone has been cleared.

Figure 13 shows typical components in workshops which have an interface to Sicat AES. The automatic earthing prevents reconnection of the power supply if there is no checkback signal from the connected subcomponents. The advantages of scalability can be used in workshops. Subs-tation and control center can be merged or control levels can be omitted. The control components of Sicat AES have type approval. Project-specific individual acceptances of the components and control software are therefore not required.

5.3 Automatic earthing for maintenance and emergencies

The use of the Sicat AES for maintenance depends on the specifications of the infrastructure operator. The automa-tic earthing ensures a safe earthing state and displays the work boundaries. In Germany and other countries, auto-matic earthing systems are expressly forbidden except for acute emergencies, because visible earthings are required in the work zone area.

It is conceivable to completely equip a line with automa-tic earthing systems, but it is not essential in many cases or for large networks. An automatic earthing system can be advantageous on lines with frequent train services and tight time windows for maintenance.

Outside tunnels, for example in main stations, there is currently no recommendation to use automatic earthing systems. When faults occur in traction units and persons have to be rescued but the state of the overhead contact line cannot be ascertained, the rescue action can only start after written confirmation has been received from the inf-rastructure operator that the overhead contact line has been disconnected and the mobile earthing devices have been applied. In main stations, an automatic earthing sys-tem can be used as part of the emergency provisions in order to reduce the waiting times of the rescue teams. In special applications, such as customs switchings, auto-

Figure 13: Sicat AES interfaces and dependencies from and to other components in maintenance halls

Automatic earthing systemSicat AES

Key desk

SCADA

Roof-height maintenance platform

Signaling and safety systems

Hazard OFF

Roof conductor rail

Wash plant

Jacking system

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matic earthing of the overhead contact line can be used advantageously before the consignment is checked.

5.4 Automatic earthing for DC mass transit systems

As there is no standard European specification compara-ble with the TSI SRT for tunnel safety on mass transit sys-tems that are typically operated with up to 1.5 kV DC, there is also no specification for emergency earthing. Conse-quently, the national regulations and laws in this case, for example the German Construction and Operating Code for Tramways with the associated technical guidelines, such as the Technical Guideline for Fire Protection, as well as tech-nical rules and regulations, such as DIN (German industrial standards) and Association of German Transport Operators documents, and local requirements of the rescue servi-ces. The operator‘s control center is informed immediately in case of emergencies such as fires, train collisions and derailments. It initiates actions appropriate to the incident in compliance with the emergency plan. The 8WL6610-0 short-circuiting devices often installed cannot be remote-controlled and, if actuated, lead to short-circuiting of the overhead contact line system. Any vehicles remaining in the tunnel can no longer leave the danger area under their own power. If the infrastructure operator short-circuits and earths the overhead contact line, the start of the rescue measures may be delayed if the accident manager has to travel an unfavorably long distance. It is therefore recom-mended to coordinate the earthing from the control center by means of Sicat AES.

The basic concept of the Sicat AES has been adapted for DC mass transit systems (Figure 14). The central station is retained and coordinates up to 99 substations on diffe-rent route sections and circuit groups. There is one substa-tion with local control, but without a control panel in each power substation. The substations without local control, but with a control panel, are located at appropriate access points and emergency entrances for rescue services. The number of components in the overhead contact line equip-ment may be reduced in comparison to those in mainline applications with AC traction power supplies. The voltage measurement can be tapped via the isolation amplifiers in the feeder outputs in the power substations. The only essential components are the earthing switches and the electrical warning signs at each of the section boundaries. The overhead contact line is disconnected by the installed section feeding switches.

Literature

[1] Anforderungen des Brand- und Katastrophenschut-zes an den Bau und den Betrieb von Eisenbahntun-neln. Richtlinie des Eisenbahnbundesamtes vom 01.07.2008.

[2] Kruse, Klaus: Brand- und Katastrophenschutz in Eisenbahntunneln. Richtlinie der Deutsche Bahn AG, Version 3, August 2003.

[3] DIN VDE 0105-100:1997-10 Betrieb von elektrischen Anlagen.

[4] DIN V 19250:1994-05: Leittechnik; Grundlegende Sicherheitsbetrachtungen für MSR-Schutzeinrichtun-gen.

Track 1

Track 2

Substation withlocal control equipment

Control panel

Substation A

Substation withlocal control equipment

Substation B

Substation withlocal control equipment

Substation C

SCADA

Central station

work boundary

Communication mediumacc. to IEC 60870-5-101/-104

Control panel

Control panel

Control panel

work boundary

work boundary

work boundary

work boundary

work boundary

work boundary

work boundary

Figure 14: Sicat AES concept for mass transit systems with DC traction power supply.

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[5] EN 6954-1:1996-12: Safety of machinery – Safety-related parts of control systems – Part 1: General principles for design.

[6] Entscheidung 2008/163/EG vom 20.12.2007: Tech-nische Spezifikation für die Interoperabilität bezüg-lich „Sicherheit in Eisenbahntunneln“ im konventio-nellen transeuropäischen Eisenbahnsystem und im transeuropäischen Hochgeschwindigkeitsbahnsys-tem (TSI SRT) In: Amtsblatt der Europäischen Union 03.07.2008, S. L64/1–L64/71.

[7] CSM-VO, Nr. 352/2009.2009-04: Verordnung über die Festlegung einer gemeinsamen Sicherheitsme-thode für die Evaluierung und Bewertung von Risi-ken. Europäische Kommission.

[8] DIN EN 50126:2003-01: Bahnanwendungen – Spezi-fikation und Nachweis der Zuverlässigkeit, Verfügbar-keit, Instandhaltbarkeit, Sicherheit (RAMS).

[9] EN 61508:2010-05: Functional safety of electrical/electronic/programmable electronic safety-related systems – Part 1: General requirements.

[10] EN 50128:2011-06: Railway applications – Communi-cations, signalling and processing systems – Software for railway control and protection systems.

[11] EN 50129:2003-02: Railway applications – Commu-nication, signalling and processing systems – Safety related electronic systems for signalling (Corrected and reprinted in 2010-05).

[12] DIN EN 50110-1:2005-06: Betrieb von elektrischen Anlagen.

[13] IEC 60870-5-101:2003-02. Telecontrol equipment and systems – Part 5-101: Transmission protocols; Companion standard for basic telecontrol tasks.

[14] IEC 60870-5-104:2006-06: Telecontrol equipment and systems – Part 5-104: Transmission protocols – Network access for IEC 60870-5-101 using standard transport profiles.

[15] IEC 61131-3:2003-01: Programmable controllers – Part 3: Programming languages.

[16] DIN EN 50152-2:2008-6: Bahnanwendungen – Orts-feste Anlagen – Besondere Anforderungen an Wech-selstrom-Schaltanlagen – Teil 2: Einphasige Trenn-schalter, Erdungsschalter und Lastschalter mit U

n

über 1 kV. [17] DIN EN 50123-4:2003-09: Bahnanwendungen –

Ortsfeste Anlagen; Gleichstrom-Schalteinrichtungen Teil 4: Freiluft-Gleichstrom-Lasttrennschalter, -Trenn-schalter und -Gleichstrom-Erdungsschalter.

[18] EN 60044-2:2003-12: Instrument transformers – Part 2: Inductive voltage transformers.

[19] DIN 4844-1:2012-06: Graphische Symbole – Sicher-heitsfarben und Sicherheitszeichen – Teil 1: Erken-nungsweiten und farb- und photometrische Anforde-rungen.

[20] GUV-V A8:2002-06: Sicherheits- und Gesundheits-schutzkennzeichnung am Arbeitsplatz. Unfallverhü-tungsvorschrift der Gesetzlichen Unfallversicherung.

Authors‘ details

Dr.-Ing. André Dölling (33), studied transportation engineering at Dres-den Technical University. From 2003 to 2007, he was a research associate, took his doctorate at the Friedrich List Faculty of Transportation Science and became a professor for electric rail-ways. He joined Siemens AG in 2007 and, until 2012, worked on the deve-lopment of overhead line compo-nents and systems. He is now product portfolio manager in the field of rail electrification and contact lines. He has also been a lecturer for overhead contact lines at the TU Dresden since 2008, and for rail electrification at the Ohm University of Applied Sciences in Nuremberg since 2009.

Address: Siemens AG, IC SG RE PI Mozartstr. 33b 91052 Erlangen, Germany Tel.: +49 9131 7-23740 Fax: +49 9131 828-23740 e-mail: andre.doelling@siemens.com

Michael Focks (39), state certified technician for energy and automation engineering. Project manager for VA TECH SAT GmbH from 2002 to 2007 in the field of remote control and auto-mation technology for railway appli-cations. He has been with Siemens AG since 2007 as project manager for OLSP rail systems, OLA and workshop equipment.

Address: Siemens AG, IC SG BAY EA PM 1 Robert-Koch-Strasse 5 82152 Planegg, Germany Tel.: +49 89 9138-138 Fax: +49 89 9138-615 e-mail: michael.focks@siemens.com

Gregor Gumberger (45), state certi-fied technician for energy and automa-tion engineering, and master crafts-man (Chamber of Handicrafts). Project manager for VA TECH SAT GmbH from 2000 to 2007 in the field of remote control and automation technology for 50 Hz, OLA and OLSP railway appli-cations, and special projects. He has been with Siemens AG since 2007 and team leader of rail systems since 2009.

Address: Siemens AG, IC SG BAY EA PM 1 Robert-Koch-Strasse 5 82152 Planegg, Germany Tel.: +49 89 899138-174 Fax: +49 89 899138-615 e-mail: gregor.gumberger@siemens.com

Siemens AG Sektor Infrastructure & Cities Division Smart Grid Rail Electrification Mozartstraße 33b 91052 Erlangen Deutschland

electrification.mobility@siemens.com www.siemens.de/rail-electrification

© Siemens AG 2013

Die Informationen in diesem Dokument enthalten allgemeine Beschreibungen der techni-schen Möglichkeiten, welche im Einzelfall nicht immer vorliegen müssen. Die gewünschten Leistungsmerkmale sind daher im Einzelfall bei Vertragsabschluss festzulegen.