Low-voltage switching devices play a key role at the Ems Barrage in Germany. Holger Sönnichsen reports
The Ems barrage, located on the Lower Ems river in Lower Saxony, north Germany, was constructed as a storm surge barrier to hold back surges at levels of more than 3.7m asl, or about 2m above mean tide.
The 476m long structure, sitting 4km from the Dollart region on the Dutch/German boarder, also has the dual function of damming the river gage between Gandersum and Nendorp up to 2.7m between the barrage and the discharge of the river Ems into the deeper waters of the North Sea. This is necessary whenever the nearby Papenburg shipyard has to tow a luxury liner to or from the dock.
To help ensure continued operation of the barrage, German company Rolf Janssen , a partner of Siemens, was awarded the contract to configure and install a complete range of electrotechnical systems for the barrage, along with all power management and control technology components.
3WL circuit breakers
All infeeds and couplings use in for the project’s downstream consumer mains are based on Siemens’ communication and diagnostics capable Sentron 3WL circuit breakers (see factfile).
These devices offer the system operator the major advantage of being able to read off all operating states, tripping events as well as the complete history of each individual breaker from the control centre For this purpose, the Ems barrage has been interlinked with Profibus Decentralised Peripherical (Profibus-DP) Operating System on an optical waveguide basis. The Profibus-DP fieldbus is based on the European standard EN 50170 (part 2), and is designed especially for communication between automation control systems and distributed I/O at the device level.
The basic data of this construction project reveals why the aspect of communication is of such great significance for it. The installed electrotechnical and control systems combine an overall capacity of 8500kVA. The distance between the main dikes amounts to
1040m at the barrage, while the construction’s total width, including seven flow openings, measures 476m. A cable raceway spanning 2800m accommodates cables and lines with a total length of 75,000m, and the switchgear and controls add up to an overall length of 110m. All of these elements need to be able to efficiently communicate with the others.
‘Reliable communication and diagnostics capable building components are of the essence for a project of this scope’, insists Rolf Janssen Managing Director Karl-Heinz Meinders. The 3WL Sentron circuit-breakers by Siemens, for example, protect the six gigantic pumps who produce an overall power of 6300kW from the network and help attain the partially required flow rate of 100,000 litres/sec.
The importance of their availability is due to the fact that, because of environmental reasons, the planning decree provides for a limitation of the total damming time to 104hrs/yr. The Sentron WL air circuit-breakers were even re-tested by Janssen to confirm their performance capacity. Karl-Heinz Meinders summarises: ‘Thanks to the excellent heat dissipation, we were, for example, able to install circuit-breakers with a nominal current of 4000amps at points which are actually subject to a flow of 4000amps.’ Therefore, when properly installed, these low-voltage switching devices need not be overdimensioned.
Communication in the control system
Communication is just as important to the control system as it is to the power side, the complete Ems barrage, including gates and pumps, is controlled and monitored by a PCS7 process control system.
Rolf Janssen engineers compiled the complete functional specifications and programmed the process. Network and bus structures in redundant optical waveguide technology connect the distributed automation units in the piers with the control station in the operating centre.
Measured values, operating states, switching commands and diagnostic information are exchanged at a speed of up to 100Mbit/sec. The PC or monitor systems in the control station store and visualise the values.
Communication and diagnostics capable switching devices are of decisive importance in a system such as this, therefore the Rolf Janssen relies on the ‘Siemens Motor Protection and Control Device – Distributed Peripheral Devices’ (Simocode-DP) motor protection system, not only for the Ems barrage but for numerous other projects too.
These switching devices control and monitor the electric consumers of the Ems barrage. An integrated Profibus-DP interface connects the devices to the superior PCS7 process control system. This way, all relevant information on the drives and power fields is transmitted.
In the Simocode-DP system, the communication-capable motor protection and control device assures round-the-clock operation of highly available systems. Simocode-DP provides for various control functions, e.g. for direct, reversing and star-delta starters, and is able to implement application-specific controls thanks to the freely assignable inputs and outputs and the integrated truth tables, timers and counters. The integrated motor protection functions such as overload, phase failure and current asymmetry detection are rounded off by the thermistor motor protection and ground-fault detection options.
The Simocode-DP motor protection and control device can protect consumers against overloads, phase failures and current asymmetry. With the device, nine different control functions can be realised: Overload relays, direct starters, reversing starters, star-delta starters, Dahlander switches, pole changers, slider controls (actuators), solenoid valves and soft starters.
Via Profibus DP, Simocode-DP can be directly connected to a superior control. The device determines a multitude of the load feeder’s operating and statistical data which are made available to the operator for visualisation and diagnostics purposes. This data comprises: present phase current flow in percent, ON-OFF, left-right, slow-fast, slider open-closed-driving, warning and fault. In addition, the Simocode-DP comes with integrated truth tables, counters and timers.
For technical questions, contact Holger Sönnichsen, Siemens AG, A&D CD, Universitätsallee 16, D-28359 Bremen. Tel: +49 (0) 421/364-2736. Fax: +49 (0) 421/364-2249. Email: email@example.com
For questions on switchgear, contact Karl-Heinz Meinders, Rolf Janssen GmbH, Elektrotechnische Werke, Emsstraße 4, D-26603 Aurich, Germany. Tel: +49 (0) 4941/174-0. Fax: +49 (0) 4941/174-205. Email: firstname.lastname@example.org
|Sentron WL circuit-breakers|
The complete ACB range of WL circuit-breakers has been dimensioned for AC currents from 630 to 6300amps. The devices are available in three sizes, have identical depths and heights and merely differ in width, in order to make not only their application, but also control cabinet retrofitting easier. Furthermore, all internal and external accessories are suitable for WL breakers of all sizes. A 3WL circuit-breaker of any design can be set to the desired nominal current via an integrated rated nominal current module. Siemens is the only supplier worldwide to offer this unique option.
The breakers are available in three and four-pole design. Owing to three switching power classes (N/S/H) and six electronic releases, the 3WL circuit-breakers are individually adaptable components for a multitude of application cases.
The circuit-breakers are able to directly communicate with control via Profibus-DP. Sentron WL complies with the IEC 60947-2 and UL 489/ANSI C37.13 standards, so the components meet important requirements of foreign customers, which is crucial as exports to the US, are difficult without a UL approval.
Besides the aspects of modularity and application diversity, the development of the Sentron WL circuit-breaker range also concentrated on the challenge of global utilisation. This is why the devices are based on an identical operating concept and have identical dimensions, which also makes all accessories suitable for all sizes.
The units are either available in a permanent installation or a withdrawable rack design and conversion from permanent to withdrawable installation technology is possible at any time. The operating panel dimensions remain consistently identical for all breakers.
With the help of the Simaris Design planning software, the current curves of the 3WL circuit-breakers can be individually calculated and simulated. This tool supports the circuit-breakers’ fast optimisation and thus supplements the practice-oriented features of the breaker range.