The present invention relates to a circuit breaker for high-voltage
currents. As it is known, circuit breakers for high-voltage currents must be actuated
quickly and promptly. In order to meet this requirement, the use of direct actuators
of the electromechanical type would entail devices of unacceptable size; accordingly,
systems for accumulating mechanical energy are generally used. Energy accumulation
occurs over a few hundred seconds. Energy is then used and delivered over a few
tens of milliseconds.
This solution in any case entails using complex, expensive and bulky
devices which cannot be integrated with the circuit breaker poles they must operate.
In particular, if the energy is accumulated in steel springs, which have a great
mass, it is not possible to connect them directly to the movable assembly of the
pole of the circuit breaker, because their mass would significantly limit the speed
and the operation time of the circuit breaker, unacceptably penalizing its performance.
In such situations it is necessary to resort to stroke multiplier
mechanisms interposed between the spring and the movable element of the circuit
breaker, which further complicate the actuation mechanisms and make it practically
impossible to integrate it with the pole of the circuit breaker.
As regards the poles of circuit breakers, in the conventional art
the use of porcelain insulators leads to great limitations. This solution necessarily
entails using two porcelain insulators equipped with aluminum flanges (which are
cemented to the insulator in a complicated manner), which respectively contain
the arcing chamber and the insulating drive rod; the entire unit is assembled by
means of plates and covers which are expensive and bulky.
Main aim of the present invention is to provide a circuit breaker
for high-voltage currents which allows to eliminate the complicated stroke multiplying
mechanisms required to transmit motion to the movable parts of the pole of the
Within the scope of this aim, an object of the present invention is
to provide a circuit breaker for high-voltage currents which allows to reduce the
energy required to transmit motion to the movable contacts of said circuit breaker
so as to improve its performance in terms of speed and promptness of intervention.
Another object of the present invention is to provide a circuit breaker
for high-voltage currents with a pole having a smaller number of components, a
reduced weight and, insulation levels being equal, smaller size.
Further but not last object of the present invention is to provide
a circuit breaker for high-voltage currents which is highly reliable, has reduced
testing times, is relatively easy to manufacture and at competitive costs.
This aim, these objects and others which will become apparent hereinafter
are achieved by a circuit breaker for high-voltage currents which comprises a vertical
rod-like insulator, at least one arcing chamber arranged inside said insulator
and containing fixed contacts and movable contacts, said movable contacts being
connected to actuation means for opening and closing the circuit breaker, characterized
in that it comprises first and second elastic means, for opening and for closing
respectively, which are made of insulating material and are arranged inside said
insulator, and means for actuating the circuit breaker which are coupled to the
base of said insulator.
Further characteristics and advantages of the present invention will
become apparent from the following detailed description of preferred but not exclusive
embodiments of the circuit breaker according to the invention, illustrated only
by way of non-limitative example in the accompanying drawings, wherein:
- Figures 1, 2 and 3 are partially sectional views of a first embodiment of the
circuit breaker according to the invention; and
- Figure 4 is a partially sectional view of a second embodiment of the circuit
breaker according to the invention.
With reference now in detail to Figures 1, 2 and 3, the circuit breaker
according to the invention comprises a pole which is constituted by an insulator
4, by fixed contacts 1 and by movable contacts 2. An electric power tap 3 protrudes
from the insulator and supports a movable contact holder 10 by means of an intermediate
Inside the insulator 4 of the pole there are provided elastic means
which are conveniently constituted by two springs 6 and 7, respectively for opening
and for closure, which are made of insulating material. Advantageously, in the
opening spring 6 one end is connected to a movable drive rod 5, which is also made
of insulating material and which, by actuating the movable contacts 2, allows to
open and close the circuit breaker, and the other end is fixed to the flange 11.
In the closure spring 7, one end is coupled to sliding support means 12 which are
connected, by means of a tube 13, to circuit breaker actuation means 8, and the
other end is connected to the flange 11. In particular, the tube 13 is coupled
to the drive rod 5 through engagement means 16 which are fixed to the tube 13 and
have a pawl that engages a slot formed in the rod 5.
The circuit breaker actuation means 8, according to the present invention,
comprise a gearmotor 31, a worm screw 36, two electrical engagement devices 34
and 35, and two engagement means 19 and 20 and are directly connected to the flange
9 of the insulator 4 by means of the flange 14. In this manner they are rigidly
coupled to the base of the insulator 4.
Starting from the conditions of Figure 1, in which the circuit breaker
is open and the closure spring 7 is loaded, i.e., is tensioned, the energization
of the electromagnet 35 releases the engagement means 19: in this manner, the closure
spring 7 can move freely and moves upward the tube 13 which, by being coupled to
the drive rod 5 through the engagement means 16, also moves the rod 5 in its upward
movement. The rod 5, by actuating the movable contacts 2, closes the circuit breaker
and loads, by compressing it, the opening spring 6 which is rigidly coupled thereto.
At the end of the actuation, as shown in Figure 3, the pawl of the
engagement means 16 is released by the stroke limiter 17 and the drive rod 5 engages
the engagement means 20; in this manner, the opening mechanism is made independent
of the closure mechanism.
The gearmotor 31 starts by means of the stroke limiter switch 32 and
can reload the closure spring 7 which, at the end of its loading, engages the engagement
means 19; the wheel of the gearmotor disengages from the worm screw 36 and the
gearmotor stops due to the stroke limiter 33.
Opening of the contacts, which can be performed if necessary also
during the reloading of the closure spring, occurs by energizing the electromagnet
34. In this manner, the engagement means 20 are released and the opening spring
6, as it is released, pushes down the rod 5, which opens the contacts.
With the circuit breaker according to the invention it is possible
to perform quick opening-closure-opening with the following sequence.
Starting from an operating condition in which the circuit breaker
is closed and the closure and opening springs are loaded, the following occurs:
- the engagement means 20 are released by energizing the electromagnet 34; since
the opening spring 6 is now free to move, it elongates and pushes down the drive
rod 5, which opens the circuit breaker and engages the engagement means 16. In
this situation, the circuit breaker is open, the opening spring 6 is released and
the closure spring 7 is loaded.
By energizing the electromagnet 35, the engagement means 19 are released
and the circuit breaker, as described above, closes. In this situation, the opening
spring is loaded and the insulating rod 5 is engaged with the engagement means
By re-energizing the electromagnet 34, the circuit breaker reopens.
Auxiliary contacts 18 of the insulator are switched at each actuation.
A second embodiment of the circuit breaker according to the invention
is now described with reference to Figure 4. In this embodiment too, the opening
and closure springs, now designated by the reference numerals 3 and 4, are contained
in the insulator 5 of the pole of the circuit breaker and are made of insulating
In particular, in the opening spring 3 one end is fixed to a flange
30 and the other end is fixed to an insulating rod 50 which, by actuating the movable
contacts 2, allows to open and close the circuit breaker. In the closure spring
4, one end is fixed to the flange 30, while the other end is connected to a system
constituted by a linkage 61 and a lever 62.
In this embodiment, the actuating means comprise two electric engagement
devices 39 and 41 and a gearmotor 42. Starting from the situation shown in Figure
4, in which the circuit breaker is open,the closure spring 4 is loaded (compressed)
and the opening spring 3 is released, energization of the electrical engagement
device 40 releases the kinematic chain 62, 61 and 4. The closure spring 4 is released
and, by elongating, pushes the lever 62 which, by means of the linkage 63 and the
levers 64 and 65, moves upward the rod 50, which causes the closure of the contacts
and the loading (by compression) of the opening spring 3.
At the end of the closure actuation, the lever 64 engages the electrical
engagement device 41; at the same time, the lever 66 disengages the lever 64 from
the lever 62, making the opening mechanism independent of the closure mechanism.
The gearmotor 42 can thus reload the closure spring 4. At the end of the loading
action, the spring 4 engages the electrical engagement device 40 and the gearmotor
42 disengages from the lever 62 by means of a disengagement device 43.
The opening of the contacts, which can be performed if necessary also
during reloading of the closure spring, occurs by energizing the electrical engagement
device 41, which releases the lever 64. The opening spring 3 is no longer retained
and is released, pushing the rod 50, which opens the contacts.
According to this embodiment, it is possible to perform quick opening-closure-opening
by means of the following sequence:
- starting from a condition in which the circuit breaker is closed, the closure
spring 4 and the opening spring 3 are loaded and as described above, the following
- -- the electrical engagement device 41 disengages the lever 64 and the opening
spring 3 is released, allowing the circuit breaker to open;
- -- the lever 64 engages the linkage 63;
- -- the electrical engagement device 40 releases the lever 62, the spring 4 is
released and allows to close the circuit breaker and reload the opening spring
3; at the same time, the lever 64 disengages from the linkage 63;
- -- the electrical engagement device 41 disengages the lever and the circuit
Another advantage of the circuit breaker according to the invention
is the fact that the insulator of the pole is monolithically made of composite
material coated with polymeric material. Accordingly, this allows to reduce the
number of components of the pole, its weight and, insulation levels being equal,
The circuit breaker thus conceived is susceptible of numerous modifications
and variations, all of which are within the scope of the inventive concept; all
the details may also be replaced with other technically equivalent elements.
In practice, the materials and the dimensions may be any according
to requirements and to the state of the art.