Maintenance-free AC vacuum switch

Switching on overhead wire voltage without auxiliary energy

Munich, 7.7.08: For electric locomotives and electric multiple-unit trains that are operated with alternating current, Schaltbau is offering a special solution. The CVB25 (Circuit Vacuum Breaker) is an AC vacuum switch that needs almost no energy to safely switch on the overhead power: The energy needed for it to operate is stored in an elastic spring. To trigger the starting process, a minimal amount of electrical energy is needed to release the mechanical lock – and this can even be provided by an almost empty vehicle battery. More information can be obtained from www.schaltbau-gmbh.com.

Vacuum switches in the CVB model series are used as main switches and protective devices for AC railway vehicles. They are generally mounted in the roof between the current collector and the main transformer. The new CVB model series is designed to switch off operating currents, overcurrents and short-circuit currents. The CVB25 is used for preference in new locomotives and electric multiple-unit trains. But the roof structure does not need to be changed if it is used to replace existing circuit breakers and load break cut-outs. The vacuum breaker is also compatible with standard roof earthing switches.
The main feature of the CVB is its drive system provided with a spring that stores the energy which is needed to activate the main contact. The spring is (during operation, with the battery power switched on) loaded in less than 3 seconds by an electric motor and mechanically locked. In order to close the main contacts, only the tiny amount of electrical energy is therefore needed to activate the energy saved in the spring for the switching process. Once the main contacts are closed, their position is held by the holding magnets and an electromagnetic jack. All processes are controlled in an electronic control unit. This monitors the  functions of the main contacts, controls the electric motor for charging the spring and ensures safe operation even in emergency situations. An interface to the control switching circuit of the rail vehicle is also provided. In the event of a power failure, the vacuum breaker automatically switches off without any external supply of energy (fail-safe principle).
The vacuum circuit breaker, which has been developed for an operating voltage of 25 kV AC (50 and 60 Hz) meets the requirements of EN 60077-4, EN 50124-1, EN 60694, EN 50155 and EN 50121-3-2, and offers the following features:

  • Greatly reduced wear on the switching element and long working life because of the use of a vacuum tube
  • Switching on with low battery power is possible
  • No second energy source needed apart from battery power
  • Fail-safe principle: the CVB switches off if the power fails without any external energy supply
  • Clearly reduced maintenance costs, practically maintenance-free because
    • no pneumatic components (no expenditure on air treatment, no danger of freezing, etc.)
    • no need to adjust the mechanism (e.g. setting the lift) for a period of over 200,000 switching operations

  • Feedback of actual switching state
  • Much greater reliability and thus availability through the electrical drive and spring store with redundant spring return system
  • Compatible with various compressed air switches and pneumatically driven vacuum main switches and with standard earthing switches
  • Diagnostic unit for real time monitoring and saving of most important operating data
  • Self-protection of the CVB when switching to an existing short circuit through locking after 3 switching attempts within a minute.
  • Little noise and vibration
  • Independent of locomotive manufacturers

 

The field tests which are being carried out at present are close to completion. For a year the CVB series vacuum breakers have been in trouble free operation at Mitteldeutsche Eisenbahngesellschaft MEG (15 kV version) and at the Hungarian State Railway MAV (25kV version). There they have proven their practical suitability and reliability. As expected, there were no maintenance costs for this time. In order to further round off the field tests, two additional CVB series vacuum breakers will be in service in Russia by September 2009. For that purpose the CVBs were qualified for temperatures of up to -50° C and their functionality validated by a test laboratory in Prague

 

The company:

"Connect – Contact – Control". This is the motto for Schaltbau GmbH as it develops and manufactures electromagnetic components for railway and industrial applications. Founded in 1929, the company now has six sites of its own and over 50 sales partners worldwide. Subsidiary companies in France, the USA and China strengthen the company's international focus. The range of products manufactured includes connectors, snap-action switches, contactors, and electrics for rolling stock. Products are developed for specific orders or for series production. All products are characterised by their superb quality, outstanding reliability and long working life. Schaltbau GmbH operates a certified quality management system in accordance with DIN EN ISO 9001 and an environmental management system in accordance with DIN EN ISO 14001. The company has been certified as a Q1 supplier to Deutsche Bahn (German Railways) since 2004.



 

 

Contact

Schaltbau GmbH

Hollerithstraße 5
D-81829 München

Svenja Bierbrauer
Press

Phone +49 (0)89/93005-153
Fax +49 (0)89/93005-156
presse@schaltbau.de

 

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