High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Operating mechanism structure or arrangement
Reexamination Certificate
2002-11-18
2004-08-24
Donovan, Lincoln (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Operating mechanism structure or arrangement
C218S140000
Reexamination Certificate
active
06781079
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an actuator for high voltage air break electrical switches.
BACKGROUND OF THE INVENTION
Prior art air break switches are relatively large switches which require significant force to operate. Such switches are usually mounted on top of power poles and are designed to immediately break the power supply along an overhead high voltage distribution line or number of lines. Present air break switches are activated by manually operated handles. These handles are located at the base of a power pole to which access is only available to authorized maintenance crews. Prior art air break switch actuators usually comprise a lever mechanism biased to open or close a switch and to hold the switch in the open or closed position. The biasing action is normally due to a powerful spring under compression between two points corresponding to the switch's open or closed positions. The spring applies force in either direction away from a position between the open and close positions to the lever operating the switch which is also held in the open or closed position by the force of the spring. This introduces certain problems mainly that when the actuator is driven in a reverse direction, the spring pressure is relieved from the air break switch for the time that the spring travels to a changeover point. At the changeover point the spring commences to open or close the switch by applying force in the relevant direction. The problem is when spring force which is holding the switch closed is removed the switch contacts for this brief period are only held together by gravity with the potential for arcing should they commence to separate due to some external force or pressure. Importantly, the force required to open a switch is greater than the force required to close a switch. As a result, actuators therefore are limited to springs which are large enough to provide enough force to open the switch. It is the inventor's observation that prior art actuators do not have the ability to vary the spring force as required to open or close the switch so that more compact and springs which apply less force to the switch mechanism can be used. In addition, as prior art actuators have an exposed sliding slot mechanism, they are prone to be vandalised and can be affected by adverse weather conditions such as the mechanism icing up, being corroded by salt in a marine environment and/or jamming due to the nesting activities of birds and bird droppings.
Utilising existing ball screw linear drives and associated electronics, it is now possible to operate air break switch actuators remotely by means of radio control. This negates the necessity for maintenance crew have to travel to a fault site in order to operate the air break switch to disconnect power along the relevant faulty line or lines. The switch can be actuated well in advance to limit or prevent further damage to the grid and to isolate faulty sections of line. The introduction of remote control mechanisms, however requires efficient and smooth operation of the actuator apparatus. Prior art switch actuators which may be affected by weather, vandals or jammed by other factors present a significant reliability problem in terms of remote or radio controlled operation.
It is therefore an object of the present invention to alleviate to some degree some of the problems associated with prior art air break switch actuators or to at least provide the public with a useful choice.
SUMMARY OF THE INVENTION
In a first aspect the present invention consist in an air break switch actuator comprising or including:
a structure providing means to locate in position,
a switch actuating means adapted to move between a first and a second position corresponding to an open or a closed position, or vice versa, of a switch,
operating means, operable manually and/or by a drive unit,
a connection means connecting the operating means with the switch actuation means to positively displace the switch actuation means at least during part of the movement of the operating means
biasing means applying, directly or indirectly at least during part of the movement of the switch between the first and second positions, a biasing force to urge the actuating means to the first or the second position.
Preferably the biasing means acts directly or indirectly at least during part of the movement of the switch between the first and second positions, to bias the switch actuating means away from a snap through region of movement thereof, in a direction towards the first or second position.
Preferably said biasing means acts on the connection means to bias the connection means via a linkage means, there being provided as part of said linkage means a trigger means to move the direction of the biasing force applied by the biasing means to the connection member dependent on the position of said connection.
Preferably said trigger means is engaged to the linkage mechanism and becomes operative, to move the direction of the biasing force when said connection means is at the snap through region, by being displaced by the movement of said connection means.
Preferably said linkage means is configured such that said trigger is actuated by the movement of said connection means to advance the snap though point to occur earlier in said snap though region.
Preferably said switch actuating means comprises a switch lever rotatably movable about lever axis between two positions corresponding to the open and closed positions of said switch.
Preferably said operating means comprises an operating lever rotatably movable about said lever axis between two positions corresponding to the open and closed positions of said switch.
Preferably said connection means is a plate which is rotatable about said lever axis and includes a connection member for engagement and to provide positive displacement by the operating means, to the switch actuating means at least during part of the movement of the operating means.
Preferably said operating means includes an operating plate directly connected to and for rotation by said operating lever, said operating plate having at least one slot, concentric with said lever axis, with which said connection member of said connection means is engaged at least during rotation of said operating means towards said snap through point, said connection means is rotatably displaced by the movement of said operating plate up to the point at which snap through occurs.
Preferably said switch actuation means includes a switch plate directly connected to said switch lever to operate the rotation of said switch lever respondent to the displacement thereof by the connection member.
Preferably said switch plate includes as least one slot, concentric with said lever axis, with which the said connection member of said connection means is engaged to displace said switch plate at least through and beyond said snap though point.
Preferably said at least one slot of said switch plate is of identical shape to the at least one slot of said operating plate.
Preferably said at least one slot of said operating plate, when said connection plate is at its extremes of rotation, is in alignment with the at least one slot of said switch plate.
Preferably said connection plate is intermediate of the operating plate switch plate, said connection member being a transverse pin extending into the slots of the connection plate.
Preferably said operating plate has two slots and said switch plate has two slots, said connection plate providing two connection members, one for each of the pairs of slots.
Preferably said linkage means includes a connection rod acting directly on and at a circumferential point of the connection plate, said connection rod connected to a crank pivoted about a fulcrum provided by said trigger arm, wherein said biasing means is provided to act on said crank to bias said connection rod toward said connection plate.
Preferably said trigger arm is pivotably located to said structure providing means to displace said fulcrum with a component of movement in a direc
Donovan Lincoln
Fish & Richardson P.C.
Fishman M.
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