High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Vacuum
Reexamination Certificate
2002-09-11
2004-02-03
Enad, Elvin (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Vacuum
C218S128000, C218S129000
Reexamination Certificate
active
06686552
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a contact for a vacuum interrupter, and a vacuum interrupter using the contact.
For obtaining enhanced interrupting performance of the vacuum interrupter, electrodes need to receive arc produced therebetween at interruption (shutoff) by their entire surfaces without concentrating arc onto specific spots. The structure for forming a longitudinal magnetic field between electrodes, i.e. the longitudinal magnetic-field applying method, is adopted to receive arc by the entire surfaces of the electrodes. Generation of the longitudinal magnetic field between the electrodes encloses arc, leading to less loss of charged particles from an arc column, excellent arc stability, restrained temperature rise of the electrodes, and enhanced interrupting performance.
U.S. Pat. No. 4,620,074 (equivalent of Japanese Patent Examined Publication No. Heisei 3(1991)-59531 [=JP3059531B]) describes “a contact arrangement for vacuum switches” adopting the longitudinal magnetic field application method. A contact carrier in a form of a hollow cylinder has an end face which is formed with a contact plate. The contact carrier has a periphery formed with a slit (referred to as “slots” in ABSTRACT). Length (referred to as “predetermined height HT” in ABSTRACT), the number of slits, and an azimuth angle of the slit of the contact carrier are defined with respect to an outer diameter of the contact carrier.
FIG.
15
and
FIG. 16
show a construction of a contact of a vacuum interrupter, according to U.S. Pat. No. 4,620,074.
A contact
01
has a contact carrier
02
and a contact end plate
03
. The contact carrier
02
has a first end (lower end in
FIG. 15
) to which the contact end plate
03
is brazed. As a result, the contact
01
is shaped substantially into a cup. The contact carrier
02
has a second end (upper end in
FIG. 15
) to which a contact plate
04
is brazed. The contact carrier
02
has a periphery which is formed with a plurality of inclined slits
05
each of which is inclined by a predetermined angle. An area between two adjacent inclined slits
05
is defined as a coil part. Moreover, the contact plate
04
is formed with a slit
06
connecting to the inclined slit
05
. The slit
06
is offset by a distance b from a center O of the contact
01
. As is seen in
FIG. 15
, there is defined an inclination angle &agr; of the inclined slit
05
, relative to an axis of the contact
01
. As is seen in
FIG. 16
, there is defined an azimuth angle &bgr; which is an opening angle of the inclined slit
05
, with respect to the center O of the contact
01
.
The vacuum interrupter using the above contact
01
shows the following features:
A current Ia flowing circumferentially around the contact
01
as is seen in
FIG. 15 and a
current Ib flowing spirally on the contract plate
04
as is seen in
FIG. 16
secure a magnetic flux density between electrodes during current interruption. The magnetic flux density caused by the current Ib shows a concentrated distribution around an axis of the electrode, thereby causing a concentration of arc substantially in the center during the current interruption. The thus concentrated arc disables interruption of a great short circuit.
For interruption of a high voltage and a heavy current, larger coil diameter and greater gap between the contacts are required. In this case, however, the magnetic flux density between the electrodes is likely to become short, thus destabilizing the arc between the electrodes and leading to incapability of interruption.
Moreover, for securing the magnetic field, the azimuth angle &bgr; of the inclined slit
05
(formed in the contact carrier
02
) needs to be greater. In this case, however, the contact
01
itself may become short in strength. Thereby, opening and closing the contacts
01
may deform the contacts
01
, thereby deteriorating voltage withstandability as well as interrupting performance.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a contact for a vacuum interrupter, and a vacuum interrupter using the contact.
According to a first aspect of the present invention, there is provided a contact for a vacuum interrupter, comprising: 1) a contact plate; and 2) a contact carrier. The contact carrier comprises: a first end face which is fitted with the contact plate, and a peripheral face which is formed with a slit portion in such a manner as to form a coil part. The coil part flows a current such that a longitudinal magnetic field is formed in an axial direction of the contact carrier. The first end face fitted with the contact plate is formed with a circumferential slit portion which connects to the slit portion.
According to a second aspect of the present invention, there is provided a vacuum interrupter, comprising: a first contact fixed to a peak end of a stationary rod which is fixed to a first end plate of a vacuum container; and a second contact fixed to a peak end of a movable rod which is fixed to a second end plate of the vacuum container opposite to the first end plate. The second contact opposes the first contact substantially coaxially in such a manner as to define a predetermined gap G therebetween in the following range: 15 mm≦G≦100 mm. Each of the first contact and the second contact, comprises: 1) a contact plate; and 2) a contact carrier. The contact carrier comprises: a first end face which is fitted with the contact plate, and a peripheral face which is formed with a slit portion in such a manner as to form a coil part. The coil part flows a current such that a longitudinal magnetic field is formed in an axial direction of the contact carrier. The first end face fitted with the contact plate is formed with a circumferential slit portion which connects to the slit portion.
According to a third aspect of the present invention, there is provided a contact for a vacuum interrupter, comprising: 1) a plate; 2) a carrier having a first end face mounted to the plate; and 3) slits formed in the carrier. The slits define a coil portion in the carrier. A current passing through the coil portion generates a longitudinal magnetic field along an axial direction of the carrier. The slits comprise a first slit which comprises: a circumferential slit portion formed in the first end face of the carrier, and an inclined slit portion formed in a peripheral face of the carrier at a predetermined inclination angle &agr; with respect to an axis of the carrier and connected to an end of the circumferential slit portion.
According to a fourth aspect of the present invention, there is provided a vacuum interrupter, comprising two contacts disposed coaxially to oppose each other. A predetermined gap G between the two contacts is given by 15 mm≦G≦100 mm. Each of the two contacts comprises: 1) a plate; 2) a carrier having a first end face mounted to the plate; and 3) slits formed in the carrier. The slits define a coil portion in the carrier. A current passing through the coil portion generates a longitudinal magnetic field along an axial direction of the carrier. The slits comprise a first slit which comprises: a circumferential slit portion formed in the first end face of the carrier, and an inclined slit portion formed in a peripheral face of the carrier at a predetermined inclination angle &agr; with respect to an axis of the carrier and connected to an end of the circumferential slit portion.
According to a fifth aspect of the present invention, there is provided a contact for a vacuum interrupter, comprising: 1) a plate; 2) a carrier having a first end face mounted to the plate; and 3) means for forming slits in the carrier. The forming means defines a coil portion in the carrier. A current passing through the coil portion generates a longitudinal magnetic field along an axial direction of the carrier. The forming means comprises a first slit which comprises: a circumferential slit portion formed in the first end face of the carrier, and an inclined slit portion formed in a peripheral face of the carri
Furuhata Takaaki
Matsui Yoshihiko
Nishijima Akira
Takebuchi Hidemitsu
Enad Elvin
Fishman M
Foley & Lardner
Kabushiki Kaisha Meidensha
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