Electricity: motive power systems – Motor-reversing
Reexamination Certificate
1998-06-23
2001-09-04
Salata, Jonathan (Department: 2837)
Electricity: motive power systems
Motor-reversing
Reexamination Certificate
active
06285147
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a motor-operated operating device and a method for operation of an electric switching device. The operating device is intended for connection to an electric switching device and, in particular, to an electric switching device with a rotating operating shaft with different directions for closing and opening operations.
BACKGROUND ART
Certain switch disconnectors, for example ABB Kraft AB's switch disconnector of type NAL/NALF designed for medium voltage, have an operating spring in the form of a torsion spring, which gives the contacts of the disconnector a rapid movement upon opening and closing of the disconnector. The operating spring is mechanically connected to an operating shaft for tensioning the spring and to the contacts of the disconnector. In one embodiment of this disconnector, the spring is tensioned with the aid of an operating device connected to the operating shaft until a dead center is passed, whereby opening and closing, respectively, take place. In another embodiment, the operating spring is tensioned but the movement is stopped after passage of the dead center. The relevant operation can then be released with the aid of, for example, a release magnet.
Prior art motor-operated devices have a screw driven by an electric drive motor by means of a gear comprising a worm gear. A nut is moved axially along the screw upon rotation thereof, and the nut is connected to the operating spring of the disconnector via a lever mechanism. It has proved that the screw is subjected to large axial forces and that large frictional forces arise in the mechanism. This makes possible a strong construction of the operating device and a drive motor with such a high power that, for economical reasons, an ac motor is required. The mechanism is also relatively complicated. These factors result in a high manufacturing cost. The high motor power also increases the costs of control and switching means for the drive motor of the operating device and make it difficult or impossible to provide battery stand-by operation of the operating device in an economically reasonable way.
From DE 311 47 27, a spring-operated operating device is known, the object of which is to provide a simple and space-saving device where a drive spring common to both directions carries out the operating movement rapidly. The operating device comprises a motor-driven drive pulley which, via a pin, drives a first cam disk in which the operating spring is arranged. The first cam disk drives, via a pin, a second cam disk which is connected to an electric switching device. The drive pulley engages with the first cam disk after a rotation of about 90°, whereupon the drive pulley rotates the first cam disk with the drive spring applied thereon to an upper dead-center position at about 180°, in which the first cam disk engages with the second cam disk. When the dead-center position has been passed, the cam disks continue the movement of the force from the drive spring, whereby switching takes place. During each operation, the drive pulley and the first cam disk move one full turn, which means that a manual operation of an electric switching device with one closing and one opening direction cannot be carried out. A disadvantage of the known device is that three discs are needed to make possible one operation. A further drawback with the device is that an operating spring is used and that this must be pre-stressed by a motor. The spring must therefore be oversized by about 20% to give sufficient safety and to overcome friction losses. The motor, in turn, must be oversized by about 20% to be able to prestress the operating spring in a reliable manner.
One further disadvantage of these prior art operating devices is that they have insufficient flexilibity during mounting, that is, that they cannot be mounted in an arbitrary manner in relation to the disconnector, for example on an optional side of the disconnector.
SUMMARY OF THE INVENTION
The invention aims to provide a motor-operated device, which
has fewer components and may be given a simpler and more compact design,
may be manufactured at a lower cost,
requires lower drive motor power,
has a high flexibility as regards mounting, and which allows manual operation of the electric switching device by means of an operating handle or the like without being obstructed by the operating device.
By arranging the operating device with one driving part and one driven part, between which a play is arranged which corresponds to the movement of a complete operation, the need of an additional component to complete the operation is eliminated. In the device according to the invention, the screw mechanism is completely eliminated and replaced by rotating components in the form of a rotating carrier means. In this way, the large axial forces of the prior art devices are completely eliminated. The large friction losses from which the known devices suffer are also considerably reduced. This, in turn, permits the mechanism to be made simpler and more compact and with fewer components, permits the drive motor to be designed for considerably lower power, and thus permits the necessary components for switching and control of the drive motor to be made simpler and less expensive. Altogether, this means that an operating device according to the invention can be manufactured at a cost which is greatly reduced compared with what has previously been possible.
Further, an operating device according to the invention is given maximum flexibility during the mounting, where necessary after a simple switching of the direction of rotation of the drive motor. It may be mounted on an optional side of a disconnector or another electric switching device, it may be mounted upside down, etc.
The low necessary driving power allow the drive motor to constitute a dc motor for low power. It has proved that in a typical operating device according to the invention, the required drive motor power is reduced to only 10-15% of the power of corresponding prior art operating devices. In addition to the positive effect this has on the cost, weight and space requirement of the device, it has the positive effect that the motor, upon voltage drop out during operational disturbances, can be driven by a stand-by battery.
In a preferred embodiment of the invention, one of the two parts of the carrier means is made as an operating wheel with a carrier and the other part as a cam disk coaxially rotating with the operating wheel. The operating wheel then suitably constitutes the driving part of the carrier means and is designed as a gear wheel, driven by the drive motor via the gear, with a carrier applied to the gear wheel, which provides a simple design of the operating device.
In a preferred embodiment of the invention, a spur gear (a straight-toothed spur gear with parallel input and output shafts) is arranged between the drive motor and the carrier means, which results in a low manufacturing cost and low friction losses.
Preferably, the operating device is designed such that the driving part of the carrier means after an operation is always returned to an original position by the drive motor. In this way, the advantage is achieved that the electric switching device, in a simple manner, can always be operated manually without being obstructed by the operating device.
The advantageous properties of an operating device according to the invention make possible the use of remote operation of disconnectors to a considerably greater extent than what has been previously practically and economically possible, which entails considerable advantages for the operation of a switchgear installation.
REFERENCES:
patent: 3733747 (1973-05-01), Fox et al.
patent: 4344252 (1982-08-01), Suzuki et al.
patent: 4556832 (1985-12-01), Rollins
patent: 4659141 (1987-04-01), Masuda et al.
patent: 4774443 (1988-09-01), Herzig
patent: 4845321 (1989-07-01), Miki
patent: 4940903 (1990-07-01), Brown, Jr. et al.
patent: 5184050 (1993-02-01), Harada et al.
patent: 5186516 (1993-02-01), ALexander et al.
patent
ABB Nordkomponent AB
Connolly Bove Lodge & Hutz
Salata Jonathan
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