The results of studies of switching off a direct current using a vacuum interrupter with a transverse axial-symmetric magnetic field at a recovery voltage of up to 9 kV are presented. The prototype of the DC vacuum contactor based on this vacuum interrupter was developed and manufactured for applications in railways. The contactor is intended for switching off DC current at a rated voltage of 3 kV. The main technical parameters of the vacuum contactor are presented. A vacuum interrupter with transverse axial-symmetric magnetic field is executed normally and includes moving (anode) and fixed (cathode) contacts and a screen system located in ceramic casing. The contacts are made of CuCr material in a 50:50 ratio (by mass), which is widely applied in ac vacuum interrupters. The moving contact is in the form of cup so that the operating area (contact field) on the side surface of the fixed contact forms a ring surface 2 mm wide with an outer radius of 11 mm. The maximal intercontact gap (moving contact travel) is 4 mm. The magnetic field in the intercontact gap is formed by a cylindrical permanent magnet located on the axis of the chamber from the side of the fixed contact. Magnets with high coercive force are applied. Power lines of the magnetic field are proposed in a 3D picture of contact and magnetic systems of the vacuum interrupter. The dimensions of contacts and magnets, as well as their positions, are selected so that the magnetic field in the intercontact gap is in parallel to the fixed contact surface, i.e., it has a mainly transversal direction in relation to the axis of the vacuum interrupter. The inductance of the magnetic field was selected by changing the length of the magnet. In the operating area of the intercontact spacing (9 mm to 11 mm) near the surface of the cathode, the radial component of the inductance of the magnetic field is maximal and the axial component of the inductance of the magnetic field is minimal and changes sign near the outer edge of the contact surface. Thus, the magnetic field in this area is almost parallel to the fixed contact surface. At a distance from the contact surface of the fixed electrode of up to 4 mm, the radial component of the inductance of the magnetic field significantly decreases. The radial and axial magnetic field averaged by the gap of 4 mm within the operating area is 90 mT and 15 mT. At increasing length of the magnet, both the radial and axial components of inductance of the magnetic field grow. The experiments on studying the dc vacuum arc extinction in the axial-symmetric transverse magnetic field were carried out at a high-current impulse bench. The dc vacuum contactor of the Russian type KBV-3-25UKHL2 was developed based on the vacuum interrupter with axial-symmetric transverse magnetic field and its batch production was carried out. The contactor includes a vacuum interrupter, integrated electromagnetic drive, and control circuit. The operating principle of the contactor is based on the quick extinction of the electric arc in the vacuum interrupter with a transverse magnetic field. When the electromagnetic drive is kept in the operating position, the coil's own inductance is used to limit the consumed capacity.
Direct-current vacuum contactor for railway transport
Gleichstrom-Vakuumschalter für die Eisenbahn
Russian Electrical Engineering ; 81 , 5 ; 237-241
2010
5 Seiten, 7 Bilder, 7 Quellen
Aufsatz (Zeitschrift)
Englisch
Ausschalten , Ausschaltstrom , Cu-Cr-Legierung , Eisenbahnfahrzeug , experimentelles Ergebnis , Feldlinie , Gleichstrom , Koerzitivkraft , Kontaktstück , Lichtbogen , Lichtbogenlöschung , Magnetfeld , magnetische Flussdichte , Massenfertigung , Permanentmagnet , Russland , Schaltgerät , technische Daten , Unterbrecher , Vakuumschalter , Vakuumschütz , Versuchsaufbau
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