EP1487003B1

EP1487003B1 - Automatic reset device for untimely trippings of circuit breakers and electrical safety equipment in general

Info

Publication number: EP1487003B1
Application number: EP04002045A
Authority: EP
Inventors: Domenico Bosatelli; Sergio Pianezzola; Augusto Contardi
Original assignee: Gewiss SpA
Current assignee: Gewiss SpA
Priority date: 2003-05-20
Filing date: 2004-01-30
Publication date: 2007-07-25
Anticipated expiration: 2024-01-30
Also published as: EP1487003A1; ITMI20030988A1; DE602004007722T2; DE602004007722D1; ES2287592T3; ATE368294T1

Abstract

An automatic reset device (1) for untimely trippings of circuit breakers, residual current-operated devices and electrical safety equipment in general, which includes a mechanism for the automatic actuation of the reset lever of an electrical device that is suitable to automatically reset the electrical device a preset time after tripping; the device includes a thermal actuator (13) that acts on the mechanism when the electrical device has tripped so that the mechanism resets the circuit breaker. <IMAGE>

Description

The present invention relates to an automatic reset device for untimely trippings of circuit breakers and electrical safety equipment in general.
Conventional circuit breakers and residual current-operated devices use mechanisms that allow to open and close the moving contact both by operating an external handle, that can be accessed by the user, and by means of the automatic action of protection devices provided inside it.
It is known that protection devices may trip in an untimely fashion, i.e., when no actual anomaly of the circuit has occurred.
The untimely tripping of the device naturally causes inconvenience to the user, who has to reach the electrical panel and restore the circuit by operating the appropriately provided levers.
The problem becomes severe if the user is not present and electric power is interrupted for hours or even days.
For example, if lightning strikes in the vicinity of the house the circuit breakers may trip and the circuit remains open until it is reactivated by the user. If the user is not present for several days, damage can be substantial: one merely needs to consider refrigerators, freezers or other critical appliances.
An aim of the present invention is to provide a reset device for untimely trippings of circuit breakers and electrical safety equipment in general, which is capable of automatically restoring the circuit even without human intervention.
An object of the invention is to provide a device that is capable of distinguishing between an untimely tripping and tripping due to an actual circuit anomaly.
A further object of the invention is to provide a device that can be applied to existing electrical equipment and is absolutely compatible with them.
A further object is to provide a device that has components that are easily commercially available and at low costs.
This aim and these and other objects that will become better apparent hereinafter are achieved by an automatic reset device for untimely trippings of circuit breakers and electrical safety equipment in general, as claimed in the appended claims.
Document US 2 614 191 discloses a device according to the preamble of claim 1.
Further characteristics and advantages of the invention will become better apparent from the following detailed description of preferred but not exclusive embodiments thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a sectional side view of the device according to the invention, shown in the position in which the circuit breaker is closed, the microswitch is open, the actuator is deactivated, the mechanism is in overtravel and the actuation spring is not loaded;
Figure 2 is a sectional plan view, taken along the line II-II of Figure 1, of the device shown in the position of Figure 1;
Figure 3 is a sectional side view of the device according to the invention, shown in the position in which the circuit breaker has tripped, the microswitch is closed, the actuator is activated, the mechanism is in the engagement/release position, and the actuation spring is loaded;
Figure 4 is a sectional plan view, taken along the line IV-IV of Figure 3, of the device shown in the position of Figure 3;
Figure 5 is a sectional side view of the device according to the invention, shown in the position in which the circuit breaker is reset, the microswitch is open, the actuator is deactivated, and the actuation spring returns the accumulated energy;
Figure 6 is a sectional plan view, taken along the line VI-VI of Figure 5, of the device shown in the position of Figure 5;
Figure 7 is a sectional side view of the device according to the invention, illustrated in the position in which the device is locked;
Figure 8 is a sectional plan view, taken along the line VIII-VIII of Figure 7, of the device shown in the position of Figure 7;
Figure 9 is a sectional side view of the device, with its swinging flap open and the device deactivated;
Figure 10 is a perspective view of the device;
Figure 11 is a plan view of the device;
Figure 12 is a detail view of the region that corresponds to the connection of the actuation bar to the actuation drum, with the device in the position that corresponds to Figure 1;
Figure 13 is a view of the thermal actuator;
Figure 14 is a detail view of the region that corresponds to the connection of the actuation bar to the actuation drum, with the device in the position that corresponds to Figure 3;
Figure 15 is a detail side view of the actuation drum of the device in the position that corresponds to Figure 5;
Figure 16 is a partially cutout detail view of the actuation drum of the device, shown in the position that corresponds to Figure 7;
Figure 17 is a sectional side view of the device according to the invention, provided with a flap that can slide instead of swinging, shown in the open position;
Figure 18 is a plan view of the device, illustrating the sliding flap in the open position;
Figure 19 is a sectional side view of the device according to the invention, provided with a flap that can slide instead of swinging, shown in the closed position;
Figure 20 is a plan view of the device, illustrating the sliding flap in the closed position.

With reference to the cited figures, a device according to the invention, generally designated by the reference numeral 1, includes a casing 2 that has the classic standardized shape and forms, at its rear face 3, a means for coupling to other pieces of equipment that are associated with an omega-shaped rail (not shown), according to DIN standards.
The casing 2 has, at its front face, a protrusion 4 in which an actuation drum 5 is positioned. The actuation drum is associated with an actuation lever 6 by means of a bar 7 that is pivoted to the lever 6 and has one end that can slide in a slot 8 of the drum 5.
An actuation spring 9 has one end that is fixed to a slider 10, in which the actuation spring is accommodated, and another end that is rigidly coupled to the actuation lever 6.
The slider 10 accommodates, in a position that is parallel to the actuation spring 9, a return spring 11, in which one end is in abutment against a wall of the slider 10 and the other end is in abutment against a fixed abutment 12 that is rigidly coupled to the casing 2.
A thermal actuator 13, of a per se known type and preferably of the commonly commercially available type, is applied to the casing 2 so that its actuation piston 14 can act on the slider 10.
The thermal actuator includes a heating member 15 that is supplied with power by an electric circuit that includes a microswitch 16.
The microswitch 16 opens or closes the power supply circuit of the heating member 15 of the thermal actuator 13 by way of the action of an elastic rocker 17 that acts on a pushbutton 116 of the microswitch 16.
The elastic rocker 17 is in turn actuated by a locking lever 18 that is associated with the drum 5.
The locking lever 18 actuates an indicator lever 19, also associated with the drum 5, at an opening 20 that is formed in the protrusion 4.
As mentioned, the device 1 is constituted by a casing that has a standardized shape so that it can be arranged side-by-side with respect to other standard modules and in particular with respect to a circuit breaker 101.
The mechanism of the reset device is connected to the mechanism of the circuit breaker 101 by means of a bar that has a triangular cross-section and constitutes the rotation axis of the drum 5, so that the rotation of the drum 5 exactly matches the rotation of the drum of the circuit breaker 101, which is provided with the usual external actuation lever.
The reset device 1 comprises an oscillating flap 50 or a sliding flap 150 that covers the actuation lever 70 of the circuit breaker when the flap 50 or 150 is in the closed position.
The function of the flap 50, 150 is to indicate clearly the activation or deactivation of the device and prevent any accidental activation thereof. It is in fact evident that the device must not automatically reset a circuit breaker that has been deactivated intentionally, for example in order to work on the line.
The flap 50, 150 deactivates the device when it is in the open position, shown in Figures 9 and 18, by means of a projection 51, 151, which, when the flap 50, 150 is in the open position, no longer retains a deactivation lever 21 that is associated with the elastic rocker 17, so that the elastic rocker 17 remains, by virtue of the elastic member included therein, in a position in which the contact is open and therefore the circuit is open, so that the microswitch 16 is not supplied with power.
Therefore, since it is necessary to act on the actuation lever 70 by opening the flap 50, 150 in order to open the contacts of the circuit breaker 101, the opening of the flap automatically deactivates the automatic reset device.
When the flap is open and the circuit breaker lever is in the open position, it is not possible to close the flap except by first closing the circuit breaker, since as shown more clearly in Figure 17, the projection 151 interferes with the deactivation lever 21. Moreover, it should be noted that the cover also covers the test button of a residual current-operated device, in the closed position, forcing the user to open the cover and then deactivate the system before opening the circuit even if he intends to do so by using the test button.
The operation of the automatic reset device when activated is now described.
The steady-state condition of the system is shown in Figures 1 and 2, in which the drum 5, which is rigidly coupled to the drum of the actuation lever of the circuit breaker, is in the position that corresponds to the condition in which the circuit breaker is closed.
The microswitch 16 is open, since the elastic rocker 17 in fact does not act on the pushbutton 116 of the microswitch 17 and therefore the thermal actuator is deactivated, since the heater 15 does not receive power. The mechanism is in an overtravel position and the actuation spring 9 is not loaded.
When the circuit breaker trips, the drum 5 rotates clockwise, with reference to the figures, and the locking lever 18 acts on the elastic rocker 17, which actuates the push button 116 of the microswitch 16, accordingly activating the thermal actuator 13.
In a per se known manner, the heat-sensitive material contained in the body of the thermal actuator, by being heated by the heater 15, pushes outward the piston 14.
According to the invention, the piston 14 acts on the slider 10, moving it to the left with reference to the figures, until it reaches the position shown in Figures 3 and 4.
During the motion of the slider, the spring 9 is loaded, because one of its ends is rigidly coupled to the slider and the other end is coupled to the actuation lever 6, which instead remains motionless in the position assumed upon tripping by way of the action of a release lever 22 that is pivoted to the actuation lever 6 and is provided with a tooth 23 that engages a fixed abutment 24 of the casing 2; these components are shown more clearly in Figures 12 and 14.
When the actuator 13 reaches the end of its stroke, the slider 10 trips the release lever 22, which frees the actuation lever 6 which, by being pulled by the actuation spring 9, acts on the actuation bar 7, turning the drum 5 into the position in which the circuit breaker is again closed.
The reset time of the circuit breaker depends substantially on the time taken by the thermal actuator to reach the end of its stroke and can be for example approximately 1-1.5 minutes.
The operating time of the actuator is used in order to obtain a reset delay that is considered ideal, but it is obvious that the delay can be reduced or increased according to the specific requirements by varying the reset mechanism.
For example, the thermal actuator might be actuated before tripping in order to arm the actuation spring, which would be always loaded and ready to act in order to reset the system instantly or a few seconds after tripping instead of after over one minute, as in the illustrated example.
System resetting is in this case performed advantageously by means of an external control.
During the reset stroke of the slider 10, the return spring 11 is loaded, because it is compressed between the fixed abutment 12 and the wall of the slider 10 that moves to the left with reference to Figures 4 and 6.
The condition in which the circuit breaker is reset is shown in Figures 5 and 6, which also show that the microswitch 16 is open, since the rotation of the drum 5, and therefore of the locking lever 18, has released the elastic rocker 17 and therefore the pushbutton 116 of the microswitch 16.
Once the actuator 13 has been deactivated, the previously loaded return spring 11 pushes the slider 10 to the right with reference to the figures and therefore also pushes the piston 14 of the thermal actuator, restoring the initial condition shown in Figures 1 and 2.
The device as described above prevents subsequent resetting if, after the first resetting after a first tripping, the system trips immediately after resetting has occurred during a persistent fault. The device in fact enters a lockout mode if the system trips immediately after resetting and no longer performs any resetting unless the operator intervenes manually.
The reset device can be provided with an additional safety system that prevents the automatic resetting in the presence of an actual and continuous anomaly of the circuit that would make any further reset attempt dangerous.
The automatic reset device would therefore be provided with an electronic system suitable to detect the fault on the line and to place the reset device in lockout mode, indicating this lockout externally by virtue of a signal that appears at the window 20.
If the device is provided with an electronic control unit, the mechanical signal can of course be replaced with one or more visual and/or acoustic signals of the electronic type, such as LEDs, buzzers, et cetera, actuated by the auxiliary electronic control circuit.
Figures 7 and 8 illustrate the lockout condition of the device, in which substantially the microswitch 16 is not operated, preventing the elastic rocker 17 from actuating the pushbutton 116.
The elastic rocker 17 is locked by the locking lever 25, actuated by means of a pivot, not shown, that is part of the mechanism of the circuit breaker 101 and enters the casing 2 through the slot 26.
The lockout condition of the device is indicated by means of the indicator lever 19, which is actuated by the locking lever 18, for example by means of a colored indicator that becomes visible through the opening 20.
The locking lever 25 can be eliminated if the device is applied to a residual current-operated device that does not have a tripped-mode lever and therefore does not act on the locking lever 25.
In practice, it has been found that the invention achieves the intended aim and objects, a device having been provided which is capable of automatically resetting, after a reasonable time interval, a circuit breaker that has tripped needlessly.
An important advantage of the invention is due to the use of a simple thermal actuator, which constitutes a reliable and extremely cheap motor, in addition to providing, by its very own nature, an ideal automatic reset time.
The device according to the invention is susceptible of numerous modifications and variations, within the scope of the appended claims.

Claims

An automatic reset device for untimely trippings of circuit breakers and electrical safety equipment in general, comprising a mechanism which is adapted to be mechanically associated with a reset member of an electrical device, said mechanism being adapted to automatically reset said electrical device a preset time after tripping, characterized in that said mechanism comprises a wax motor thermal actuator (13) that acts on said mechanism when the electrical device has tripped so that the mechanism resets said electrical device.
The device according to claim 1, characterized in that it comprises a casing (2) that has a standardized shape and forms, at its rear face (3), a means for coupling to an electrical device and to an omega-shaped rail according to DIN standards.
The device according to claim 2, characterized in that said casing has, at its front face, a protrusion (4) in which an actuation drum (5) is positioned, said actuation drum being associated with an actuation lever (6) by means of an actuation bar (7) that is pivoted to the lever (6) and has an end that can slide in a slot (8) of said drum (5).
The device according to claim 3, characterized in that it comprises an actuation spring (9) in which one end is fixed to a slider (10), which accommodates said actuation spring (9), and a second end is rigidly associated with said actuation lever (6), said slider (10) accommodating, parallel to said actuation spring, a return spring (11) in which one end abuts against a wall of the slider (10) and the other end abuts against a fixed abutment (12) that is rigidly coupled to said casing.
The device according to claim 4, characterized in that said thermal actuator (13) is applied to said casing (2) and has an actuation piston (14) that acts on said slider (10); said thermal actuator comprising a heating member (15) that is supplied with power by an electric circuit that comprises a microswitch (16).
The device according to claim 5, characterized in that said microswitch (16) closes or opens said power supply circuit of the heating member (15) of the thermal actuator (13) by way of the action of an elastic rocker (17) that acts on a pushbutton (116) of the microswitch (16).
The device according to claim 6, characterized in that said elastic rocker (17) is actuated by a locking lever (18) that is associated with said drum (5).
The device according to claim 7, characterized in that said locking lever (18) actuates an indicator lever (19) that is associated with the drum (5) at an opening (20) provided in said protrusion (4).
The device according to claim 8, characterized in that its mechanism is connected to the mechanism of an electrical device (101) by means of a bar that has a triangular cross-section and constitutes the rotation axis of the drum (5), so that the rotation of the drum (5) of the reset device (1) exactly matches the rotation of the drum of the electrical device (101), which is provided with an external actuation lever (70).
The device according to claim 9, characterized in that it comprises an oscillating (50) or sliding (150) flap that covers said actuation lever (70) of the electrical device (101) when said flap is in the closed position, in order to clearly indicate the activation or deactivation of the device and prevent any accidental activation thereof.
The device according to claim 10, characterized in that said flap (50, 150) deactivates the device (1) when it is in the open position by means of a projection (51, 151) which, when said flap (50, 150) is in the open position, does not retain a deactivation lever (21) that is associated with said elastic rocker (17), so that said elastic rocker (17) remains, by means of an elastic member comprised therein, in a position in which the contact is open and therefore the circuit is open, so that said microswitch (16) is not supplied with power.
The device according to claim 11, characterized in that said flap (50, 150) cannot be moved from its open position to its closed position without first moving to the closed position said lever (70) of said electrical device (101).
The device according to claim 12, characterized in that it comprises a release lever (22) that is pivoted to said actuation lever (6) and is provided with a tooth (23) that engages a fixed abutment (24) of said casing (2).
The device according to claim 13, characterized in that it comprises a safety system that prevents automatic resetting in the presence of an actual and continuous anomaly of the circuit that would make any further reset attempt dangerous.
The device according to claim 14, characterized in that, in the condition in which the device is in lockout mode, said microswitch (16) is not actuated, preventing said elastic rocker (17) from actuating the pushbutton (116) of the microswitch (16).
The device according to claim 15, characterized in that said elastic rocker (17) can be released by virtue of the locking lever (25) actuated by means of a pivot that is part of the mechanism of the electrical device (101) and enters said casing (2) through a slot (26).
The device according to claim 16, characterized in that the lockout condition of the device is indicated by means of said indicator lever (19), which is actuated by the locking lever (18), by means of a colored indicator that becomes visible through an opening (20) of said casing (2).
The device according to claim 17, characterized in that said safety system comprises an electronic device that adapted to detect the fault on the line and to place said reset device in lockout mode, indicating said lockout mode externally by means of a signal.