EP2947672A1

EP2947672A1 - Protective circuit breaker with toggle trip mechanism

Info

Publication number: EP2947672A1
Application number: EP14001876.3A
Authority: EP
Inventors: Marko RODE
Original assignee: Nela Razvojni Center za Elektroindustrijo in Elektroniko doo
Current assignee: Nela Razvojni Center za Elektroindustrijo in Elektroniko doo
Priority date: 2014-05-23
Filing date: 2014-05-29
Publication date: 2015-11-25
Also published as: SI24728A

Abstract

The protective circuit breaker with a toggle trip mechanism according to the invention is designed such that, using a small number of components, the toggle mechanism allows an electrical circuit to be reliably switched off in the event of a fault condition in the same and is less dependent on external factors, such as vibrations. By the lever (1) assuming a position between disconnected (OFF) and connected (ON), the mechanism signalizes a disconnection due to a fault condition in the electrical circuit. Reliable disconnecting is achieved by means of a toggle mechanism, as opposed to the unlatching mechanisms customarily used in switching devices for protecting electrical circuits in the event of a fault. The toggle mechanism of the invention comprises a lever (1), pivotally secured in the mechanism enclosure and having a cylindrical support whereon a tension spring (15) is attached, the spring (1) being connected with its lower end to an arm (19), which is connected to and arm (6) and (5), wherein the arm (5) is connected via an arm (3) to an arm (2) and to a pole bridge (9), which is journaled within the mechanism enclosure and serves as support for the contacts.

Description

The present invention relates to a protective circuit breaker with a toggle trip mechanism, wherein the mechanism and the design of the contacts allow its basic function to be performed, which is to say, the contacts to be switched on and off by means of a manually operated lever and switched off in the presence of a disturbance in the electrical circuit, say, of a current differential between the phase and the neutral conductor. The invention disclosed herein pertains to classes H01H71/10, H01H71/52 of the international patent classification.
The technical problem adequately solved by the mechanism of the proposed design is to provide a configuration allowing, in the event of a disturbance in the electrical circuit, disconnections to be consistent and less dependent on external factors. Said mechanism also enables the electrical circuit to be manually switched on and off.
Prior art solutions exploit various derivatives of mechanisms in which tripping is achieved by unlatching two levers. To interrupt the circuit, that is to separate the contacts, the mechanism of the switch as per US4679018 employs the unlatching of two levers with an additional shock-absorbing mechanism for reducing the sensitivity of the mechanism to vibration-induced tripping.
The mechanism of the present invention meets the requirements of a quick and reliable disconnection of the electrical circuit when an irregularity is encountered in the said electrical circuit, while ensuring an immediate disconnection should there be a fault current already present when the circuit is being switched on (free tripping).
The invention shall be described with reference to an embodiment thereof and the related illustrations, representing:

Figure 1: the mechanism in a switched-on state according to the invention in axonometric projection;
Figure 2: the mechanism in a switched-on state according to the invention in axonometric projection from another viewpoint;
Figure 3: the configuration of the mechanism after being switched off by a fault current;
Figure 4: the mechanism immediately prior to being switched off in a side view;
Figure 5: the mechanism in a switched-off state in a side view;
Figure 6: the configuration of the mechanism after being switched off by a fault current;
Figure 7: the mechanism in a switched-off state.

The mechanism according to the invention is composed of a lever 1, pivotally secured in the mechanism enclosure and having a cylindrical support whereon a tension spring 15 is attached, a journaled wheel 18 being mounted on a second cylindrical support. The spring 15 serves as an energy store, expanding from the beginning of activation up to the moment when the lever 1 tips over. The energy stored in the spring 15 connects a contact 10 with a contact 13 and compresses a contact spring 11.
A pole bridge 9 is journaled within the mechanism enclosure and serves as support for the contact/s 10, holding an arbitrary number thereof, in most cases two or four. The contact 10 is movably secured to the pole bridge 9 and biased by the spring 11, which is partially compressed, urging the contact 10 against the pole bridge 9 with a force 12. The spring 11 serves to cushion the contacts when they impact and to ensure with the force 12 that the contacts 10 and 13 make good connection when closed.
In the switched-on state the loaded spring 15 is attached with its upper end to the lever 1, and with its lower end to a shaft 25, which penetrates an arm 19. With its center, the arm 19 is pivotally anchored to the enclosure, so that one end thereof, specifically its point of connection with the shaft 25, is pulled upwardly by a force 14 of the loaded spring 15, while the other end thereof, specifically its point of connection with an arm 6, transmits the force 14 to the pivotally fixed arm 6. The arm 6 is pivotally connected to an arm 5 and exerts a force 7 at a distance b below the point of connection of the pole bridge 9 and the arm 5. The distance b represents the distance between the vector of the force 7 and the joint of the pole bridge 9 and the arm 5. The force 7 thus keeps the pole bridge 9 in a switched-on state, the latter, in turn, compressing the contact spring 11. As a result of the distance b, the force 7 acts on an arm 3, which is pivotally connected to the arm 5 and to an arm 2, resulting in a closing force 4 being applied at a distance a above the pivotable anchor of the arm 2. The closing force 4 starts acting as soon as the contacts 10 and 13 are brought together, pushing the arm 2 towards a rest 21, which is part of the mechanism enclosure. Thus the arm 2 is prevented from pivoting, whereby the prerequisite for the arm 5 to be retained is met and the mechanism remains switched on. The same state is also established when there is an external disturbance, such as vibration. Minor force impulses which would add up in a mechanism with a conventional locking engagement, leading to the engagement creeping and eventually to the breaker tripping, are automatically canceled with the mechanism of the invention.
In the presence of a fault condition in the electrical circuit a relay is triggered, pushing an arm 16 with a force 20, so that it rotates about its pivot in the enclosure and via the associated torque transfers a force 27 to the arm 2, making it rotate about its pivotable anchor within the enclosure, whereby the application point of the force 4 is displaced below the pivotable anchor of the arm 2 within the enclosure - the distance a being the distance between the vector of the force 4 and the pivotable anchor of the arm 2, which distance increases, leading to a further rotary movement of the arm 2 away from the rest 21. The arm 5 thus loses support and flips over its pivot within the pole bridge 9. A torque 26, generated by the force 12 until the contacts 10, 13 disconnect and by a return spring force 8, pivots the pole bridge 9, leading to a complete separation of the contacts 13 and 10. As the pole bridge 9 pivots, the journaled wheel 18 loses support, releasing the lever 1, which is pivoted by a force 14, exerted so long as the spring 15 is contracting. The lever 1 assumes the intermediate position between on and off (TRIP), clearly signalizing a fault current.
The breaker is reset for a new activation cycle by pushing the lever 1 with a force 24 into a switched-off state. Thereby a shaft 25 abuts against the lever 1, which pushes it with a force 23, pivoting the arm 19, which moves the arms 6, 5, 3 by means of a torsion spring force 22, whereby the arm 2 is pivoted to abut against the rest 21. The mechanism thus assumes its initial state. The spring 15 is slightly loaded, keeping the arm 1 in a switched-off state.

Claims

Protective circuit breaker with toggle trip mechanism for switching contacts on and off by means of a manually operated lever and switching off in the presence of a disturbance in the electrical circuit, characterized in that the toggle mechanism is composed of:
- a lever (1), pivotally secured in the mechanism enclosure and having a cylindrical support whereon a tension spring (15) is attached, a journaled wheel (18) being mounted on a second cylindrical support;

- a spring (15), attached with its upper end to the lever (1), and with its lower end to a shaft (25) which penetrates an arm (19), the said arm (19) being pivotally anchored with its center to the enclosure and with its other end to a pivotally fixed arm (6) which is pivotally connected to an arm (5), secured to a pole bridge (9);

- an arm (3), pivotally connected to the arm (5) and to an arm (2);

- an arm (16), pivotally mounted in the mechanism enclosure;

- a pole bridge (9), which is journaled within the mechanism enclosure and serves as support for the contact/s (10), holding an arbitrary number thereof, in most cases two or four, a contact (10) being movably secured to the pole bridge (9) and biased by a spring (11), which is partially compressed, urging the contact (10) against the pole bridge (9) with a force (12).
Mechanism according to Claim 1, characterized in that the spring (11) serves to cushion contacts (10, 13) when they impact and to ensure with the force (12) that contacts (10) and (13) make good connection when closed.
Mechanism according to Claim 1, characterized in that upon being switched on, the force (14) of the loaded spring (15) pulls the arm (19) upwardly, while at the other end thereof, specifically at its point of connection with the arm (6), the force (14) is transmitted to the pivotally fixed arm (6), which is pivotally connected to an arm (5) and exerts a force (7) at a distance (b) below the point of connection of the pole bridge (9) and the arm (5), keeping the pole bridge (9) in a switched-on state, the latter, in turn, compressing the contact spring (11), wherein the force (7) acts on the arm (3), which is pivotally connected to the arm (5) and to the arm (2) at a distance (a) above the pivotable anchor of the arm (2), resulting in a closing force (4) being applied, pushing the arm (2) towards a rest (21) which is part of the enclosure, thereby retaining the arm (5) via the arm (3).
Mechanism according to Claim 1, characterized in that the triggering of a relay pushes the arm (16) with a force (20), so that via the associated torque a force (27) is transferred to the arm (2), making it rotate, whereby the torque generated by the force (4) changes; the arm (5) thus loses support and flips over in the pole bridge (9); a torque (26), generated by the force (12) until the contacts (10, 13) disconnect and by a return spring force (8), pivots the pole bridge (9), leading to the contacts (13) and (10) separating completely and to the lever (1) assuming the position between connected (ON) and disconnected (OFF), thereby signalizing a disconnection due to a disturbance in the electrical circuit (TRIP).
A mechanism according to Claim 1, characterized in that by pushing the lever (1) with a force (24) into a switched-off state (OFF), a shaft (25) abuts against the lever (1), which pushes it with a force (23), pivoting the arm (19), which moves the arms (3, 5, 6) by means of a torsion spring force (22), the arm (2) pivots and abuts against the rest (21).