Electricity: motive power systems – Automatic and/or with time-delay means – Movement – position – or limit-of-travel
Reexamination Certificate
2000-11-20
2003-03-11
Donels, Jeffrey (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
Movement, position, or limit-of-travel
C318S265000
Reexamination Certificate
active
06531841
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an actuation and control device for opening/closing electric switching means, for example circuit breakers, reclosers, disconnectors and the like particularly for high- and medium-voltage transmission and/or distribution grids. The device according to the present invention is particularly adapted for use in high-voltage circuit breakers and is now described with reference to this application without limiting in any way its scope of application.
An example of a single pole operated circuit breaker provided with a conventional actuation device is shown schematically in
FIG. 1. A
first post-shaped supporting isolator
2
is arranged on a supporting frame
1
; a second isolator
3
is arranged on the upper end of said first isolator, and an interruption chamber, with interruption mechanisms constituted by fixed contacts and movable contacts, is provided inside said second isolator. Closure and opening are performed by respectively engaging and disengaging the fixed contacts with respect to the movable contacts. The movable contacts are operatively connected to an actuation rod, which runs inside the isolator
1
from the movable contacts to the base of the post. The rod is actuated by means of kinematic systems located in a housing
4
at the base of the post and operatively connected to an actuating device
5
. Actuating devices of high-voltage switches are currently of the mechanical or hydraulic type. The mechanical actuation device is generally provided with two springs, namely a closing spring and an opening spring a stroke-limiting shock absorber, a reloading motor for the closing spring, and a mechanism for the following operations: converting the motion produced by the springs into a translatory motion of the movable contact; reloading the opening spring: making the opening operation independent of the closing operation.
A schematic example of a device of this kind is shown in
FIG. 2
in which the following elements can be recognized: an opening spring
10
an opening device
11
actuated by an electromagnet an eccentric element with a lever
12
, a closing device
13
actuated by an electromagnet a main shaft
14
, an arm
15
which is rigidly coupled to the shaft
14
, a closing spring
16
, a shock absorber
17
, a drum
18
and a gearmotor
19
. There are many configurations which are alternative to the one illustrated here but in general the mechanical actuating devices of the prior art have a very large number of components which require long and complicated preliminary settings.
Although achieving the task for which they are meant, said devices have many disadvantages in addition to the already mentioned mechanical complexity. The movement of the movable contact is in fact determined exclusively by the elastic characteristic of the opening and closing springs; the rule of motion of the movable contact cannot be changed by the user but is set during design. Actuating devices of the hydraulic type, in which the movement of the movable contact is ensured by adapted hydraulic actuators can partially obviate these drawbacks but have disadvantages linked to the presence of fluids particularly owing to their temperature-sensitivity.
The absence of control over the rule of motion of the actuator also requires the presence of dampers or shock-absorbers to dissipate the residual kinetic energy at the end of the actuating operation and to avoid uncontrolled impacts against the pole. Furthermore, precision in the positioning of the movable contact is limited by a mechanism which is inherently inaccurate owing to the presence of the springs.
Owing to the large number of components the devices of the prior art require maintenance in order to maintain their nominal behavior and thus ensure repeatability of the actuation by compensating for variations due to system wear and aging. Actuation repeatability in any case has inherent limits.
SUMMARY OF THE INVENTION
Another problem is due to response times, i.e., to the elapsed time between the actuating command and the beginning of the movement of the movable contact which is currently on the order of a few milliseconds.
Another disadvantage is due to the high noise level of conventional devices which can require the use of acoustic insulation systems on the casing of the switchgear in order to limit its environmental impact.
Moreover, the energy that must be supplied is higher than the energy strictly required to move the movable contact, since it is necessary to also move the various mechanical elements of the switchgear.
The aim of the present invention is to provide an actuating and control device for electric switching means particularly of the high- and medium-voltage type such as for example circuit breakers disconnectors, reclosers and the like which allows to move the movable contact of said electric switching means according to a predefined rule of motion.
Within the scope of this aim, an object of the present invention is to provide a control and actuation device for electric switching means which has reduced mechanical complexity.
Another object of the present invention is to provide a control and actuation device for electric switchgear which allows to predefine the positioning precision of the movable contact both during opening and closing operation.
Another object of the present invention is to provide a control and actuation device for electric switching means which ensures repeatability of the maneuver optionally compensating for variations due to aging and wear.
Another object of the present invention is to provide a control and actuation device for electric switching means which has reduced response times.
Another object of the present invention is to provide a control and actuation device for electric switching means which is highly reliable, relatively easy to manufacture and at competitive costs.
This aim these objects and others which will become apparent hereinafter are achieved by a control and actuation device for opening and/or closing electric switching means such as circuit breakers, disconnectors reclosers and the like having at least one fixed contact and at least one movable contact said device comprising actuating means operatively connected to the movable contact, said actuating means supplying the energy to perform opening/closing operation. The device according to the invention is characterized in that said actuating means comprise a position control motor which is operatively connected to the movable contact and a power and control electronic unit which drives said motor so that the movable contact achieves a defined rule of motion.
Control of the rule of motion of the movable contact allows to ensure accuracy and repeatability of the switching action. The actuating device is also considerably simplified with respect to switchgear of the prior art since it allows to eliminate the opening, and closing springs the motor for reloading the closing spring and all the mechanism that allow to perform the switching cycles: accordingly the size of the actuating ,device is also reduced.
Further characteristics and advantages will become apparent from the description of some preferred but not exclusive embodiments of a control and actuating device for opening, and/or closing electric switching means illustrated only by way of non-limitative example in the accompanying drawings wherein:
FIG. 1
is a schematic view of a pole of a single pole operated circuit breaker provided with a conventional actuation device;
FIG. 2
is a schematic view of an example of a conventional mechanical actuation device;
FIG. 3
is a block diagram of a device according to the invention;
FIG. 4
is a view of a single pole operated high-voltage circuit breaker provided with a device according to the invention;
FIG. 5
is a view of a possible embodiment of the kinematic linking in a device according to the invention;
FIG. 6
is a view of another embodiment of the kinematic linking in a device according to the invention;
FIG. 7
is a view of a partic
Elli Enrico
Montelaghi Fabio
Piazza Costante
ABB ADDA S.p.A.
Donels Jeffrey
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