A bistable magnetic actuator and a circuit breaker

Claim 2

A circuit-breaker comprising a circuit interrupter (22) connected between two external terminals (20, 24), characterised by a bistable magnetic actuator (10), having a permanent magnet (3) for maintaining its state, connected via a mechanical linkage (15) to operate the circuit interrupter, a capacitative charge store connected to power the actuator, means for recharging the charge store, and electronic control means connected to control the operation of the actuator (10) in response to the current flowing between the terminals (20, 24), at least the actuator, the charge store and the control means being housed in a common housing.

Claim 3

A circuit-breaker according to Claim 1, in which the circuit interrupter (22) is a vacuum interrupter.

Claim 4

A circuit-breaker according to Claim 1, in which the mechanical linkage comprises a drive rod (15) housed with the circuit interrupter (22) in an insulating housing (17).

Claim 5

A bistable magnetic actuator (10) characterized by: a housing defined by two interlinked magnetic yokes (5, 6), outer limbs (OL) of which constitute magnetic pole pieces, and inner limbs (IL) of which are mechanically connected; an armature (AR) axially reciprocable within the housing between the pole pieces and through the inner limbs on an axis passing through both limbs of both yokes, between two stable positions at each of which it forms a magnetic circuit with a respective magnetic pole piece and breaks the corresponding magnetic circuit with the other magnetic pole piece; an axially polarised magnet (3) carried by the armature for generating the magnetic flux in the said magnetic circuits to hold the armature at one or other of the stable positions; and means (8, 9) for generating a transient magnetic field, in response to an actuation signal, simultaneously to reduce the flux in the said magnetic circuit without reducing significantly the flux within the permanent magnet, thereby to destabilise the armature without promoting demagnetisation of the permanent magnet, and to increase the flux between the armature and the other pole piece to attract the armature to that other pole piece.

Claim 6

A bistable magnetic actuator (10) characterized by: a housing defined by two interlinked magnetic yokes (5, 6), outer limbs (OL) of which constitute magnetic pole pieces, and inner limbs (IL) of which are mechanically connected; an armature (AR) axially reciprocable within the housing between the pole pieces and through the inner limbs on an axis passing through both limbs of both yokes, between two stable positions at each of which it forms a magnetic circuit with a respective magnetic pole piece and breaks the corresponding magnetic circuit with the other magnetic pole piece; an axially polarised magnet (3) carried by the armature for generating the magnetic flux in the said magnetic circuits to hold the armature at one or other of the stable positions; and means (8, 9) for generating a transient magnetic field, in response to an actuation signal, simultaneously to reduce the flux in the said magnetic circuit without reducing significantly the flux within the permanent magnet, thereby to destabilise the armature without promoting demagnetisation of the permanent magnet, and to increase the flux between the armature and the other pole piece to attract the armature to that other pole piece.

Claim 7

An actuator according to Claim 4, in which the means for generating a transient magnetic field comprises at least one stationary electromagnet (8) coupled magnetically to the armature (AR) and to the pole piece.

Claim 8

An actuator according to Claim 4 or 5, in which the permanent magnet (3) is disk-shaped.

Claim 9

An actuator according to Claim 6, in which the said transient magnetic field is generated in the direction of reciprocating motion of the armature within the armature irrespective of the position of the armature.

Claim 10

An electric circuit breaker in which the operating mechanism comprises a bistable magnetic actuator according to Claim 4.