Northern Engineering Industries Plc

James Spooner

In an arc interrupter fixed and movable contacts provide an openable current path. When the path between the contacts is opened an arc is generated between one of the contacts or a surface electrically continuous therewith providing an inner first arcing surface, and an electrode providing an outer second arcuate surface. The opening and closing of the current path is achieved by angular movement of the movable contact about an axis offset from the fixed contact. At least in the break position, the electrode surrounds and is separated by an annular gap from a coaxial arc-driving coil. The coil is accommodated within and is coaxial to the inner first surface and is included in series with both said surfaces in the arc current path at least during a later part of the movement of the movable contact to the break position for generating a magnetic field that rotates the arc to assist its extinguishment.

Arc interrupter

The rating of an arc interrupter is improved by having a movable contact assembly, which is engageable with and completely disengageable from a fixed contact in make and break positions, respectively, consisting of two main current carrying members the first of which is the last part of the assembly to disengage from the fixed contact during an opening operation. The delay in disengaging the first contact member from the fixed contact can be achieved in several ways. For example, the geometry of the first contact member can be different from the geometry of the second contact member (by the provision of an arcing tip); by the provision of a lost-motion mechanism; or by the provision of an auxiliary contact.

In arc interrupters having fixed and movable contacts and a fixed annular electrode surrounded by an arc-driving coil, the problem of electrode collapse owing to the magnetic forces generated in the electrode and the coil is reduced or obviated providing the electrode with at least one flange which has radial slots extending from the outer periphery of the flange through a substantial part of the width of the flange.

In arc interrupters having fixed and movable contacts and a fixed annular electrode surrounded by an arc-driving coil, the problem of electrode collapse owing to the magnetic forces generated in the electrode and the coil is reduced or obviated by providing the electrode with at least one flange which is supported against distortion by ferromagnetic material which forms part of a magnetic circuit produced by the coil when it is part of an arc current path.

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Sunderland, United Kingdom

James Spooner