GB1561807A

GB1561807A - Automatic circuit breaker

Info

Publication number: GB1561807A
Application number: GB39395/76A
Authority: GB
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1975-09-25
Filing date: 1976-09-22
Publication date: 1980-03-05
Also published as: BE846489A; SE7610347L; CH607309A5; ES451813A1; FR2326026A1; SE407486B; DK375576A; FR2326026B1; IT1068329B; ATA573476A; NL7608123A; HU172090B; AT364019B; GR61199B; DE2542861A1; DE2542861B1

Description

(54) AUTOMATIC CIRCUIT BREAKER (71) We, SIEMBNS AKTIEN BSELL- SCHAFT, a German company of Berlin and Munich, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an automatic circuit breaker including a manually operable actuator, a latch, and a contact arm connected to the latch and carrying a contact and being movable between "on" and "off" positions of the circuit breaker in which said contact respectively engages with and disengages from a further contact.

According to the invention, there is provided an automatic circuit breaker including a manually operable actuator, a latch, and a contact arm connected to the latch and carrying a contact and being movable between "on" and "off" positions of the circuit breaker in which said contact respectively engages with and disengages from a further contact, in which: the actuator is pivotally mounted and has a handle portion by which the actuator may be manually manipulated and a forked portion which embraces said latch and said contact arm; guide surfaces are provided on said actuator and latching pins are provided on said latch to engage said guide surfaces so as to control the movement of the latch in dependence upon the movement of the actuator so that opening movement of the actuator is accompanied by disengaging movement of the contact arm and its contact from said further contact, and closing movement of the actuator is accompanied by engaging movement of the contact arm and its contact towards said further contact; and in which each latching pin engages a part of the corresponding guide surface, when the contact arm is in the "on" position of the circuit breaker, at which the normal to said part of the guide surface extends adjacent to but to one side of the pivotal axis of the actuator so that a torque is applied to the latch and to the contact arm effective to maintain the contact arm in the "on" positions of the circuit breaker.

An embodiment of automatic circuit breaker according to the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows the circuit breaker in a switched-on position; Figure 2 shows the circuit breaker in a manually switched-off position; Figure 3 shows the circuit breaker in a switched-off position occasioned by an automatically operating control mechanism; and Figure 4 shows, in perspective, a manually operable actuator lever of the circuit breaker.

The automatic circuit breaker has a manually operable actuator lever provided by a handle 1 integral with a lever 2. The lever 2 is forked and has two side elements extending parallel to the plane of the drawing (the prongs of the fork). A latch 3 cooperates with the lever 2 and also with a keeper 4.

The latch 3 acts on a contact arm 5 bearing a contact member 6 and in the contacts closed or "on" position the contact 6 bears against a cooperating fixed contact 7. The contact arm 5 is pivoted in a forked end of the latch 3 remote from the keeper 4 on a pivot 10.

The forked limbs of the lever 2 receive therebetween the latch 3 and the contact arm 5, and at the end remote from the handle 1, the lever 2 is pivotally mounted on a pivot 8. As seen particularly in Figure 4, one edge of eachside of the fork of the lever 2 is formed with a guide surface 9 to be engaged by pins 11 which are provided one on each side of the latch 3. The pins 11 are separately guided for up and down movement in fixed slots 16 provided in side plates or housing walls of the automatic circuit breaker.

Each guide surface 9 includes an arcuate recess into which a corresponding pin 11 can be guided when the handle 1 ispivoted about pivot 8 from the position of Figure 1 to the position of Figure 2. A normal 12 to the part of the profile of the guide surface 9 adjacent to the position of the pin 11 shown in Figure 1 (the switchedon position of the circuit breaker) extends close to but to one side of the pivot 8 of the lever 2 whereby a torque 13, generated by lever arm 15, is applied to the latching lever 3 via pins 11 to urge the lever 3 and the contact arm 5 in the direction 14 so as to maintain engagement between the contacts 6 and 7. Thereby, effective and simple self-locking in the "on" position of the circuit breaker is achieved.

A torsion spring 17 is provided to urge the lever 2 into the "off" position and in a direction opposite to the direction 14. Instead of a torsion spring 17, it is also possible to attach a tension spring 18 at a suitable location to the lever 2. The tension spring 18 engages with the contact arm 5 on the side of the pivot 10 remote from the contact 6, to enable rapid opening of the latter.

A stop 19 limits the path of movement of the contact arm 5 in an opening direction.

The path of travel of the handle 1 or of the lever 2 towards the "on" position of the circuit breaker can be limited by a stop 20 formed on the housing of the automatic circuit breaker.

The "off" position of the contact arm 5 is defined not only by the stop 19 by also by a stop 21 arranged to co-operate with the end of the contact arm 5 remote from the contact 6. By virtue of the positioning of the two stops 19 and 20, the pivoting position takenup by the contact arm 5 relative to the pivot 10 is determined.

The keeper 4 is mounted to be pivotal about a pivot 23 by means of a lever 22.

Automatic opening of the contact breaker recurs when there engages, at the lever 22 in the direction of the arrow 24 according to Figure 3, a bimetallic element or the armature of a magnetic tripping device.

Thereafter, the latch "nose" 25 of the latch 3 slides over a half-shaft 26, and the latch 3 and the contact arm 5 move from the Figure 1 position to the Figure 3 position to open the circuit breaker.

For manual opening of the contact breaker, the handle 1 is displaced oppositely to the direction 14 into the position according to Figure 2. The pins 11 of the latch 3 meanwhile slide in the slots 16 and along the guide surfaces 9 until they enter the arcuate recesses of the guide surfaces 9 (as shown in Figure 2).

Furter opening movement of lever 2 is accompanied by downward movement of latch 3 (through the intermediary of the pins 11 held in the arcuate recesses of surfaces 9), and also the contact arm 5, so that the contact 6 moves away from contact 7 in the direction 28. The separating force created by movement of the handle 1 and applied to the displaceable contact 6 may even be effective to seperate welded-together contacts 6 and 7. The seperation of the contacts 6 and 7 may be promoted, in cases of difficulty, by the engagement of hooked part 27 of the contact arm 5 with the pins 11 so as to apply a clockwise turning moment to the contact arm 5 about pivot 10 which additionally urges the contact 6 away from contact 7.

Especially uniform force transmission and guiding with regard to the contact 6 is achieved if the latch 3 is forked, receiving between it the hooked part 27 and holding the pivot 10 for the contact arm 5.

The automatic opening of the contact breaker as shown in Figure 3, due to deflection of the keeper 4 is initiated in direction 24 when a current surge through the armature of the magnetic trip acts on the lever 22, or in the event of thermal overloading so that the bimetallic element responds.

When the latch 3 is freed with its latch "nose" 25 from the half-shaft 26, the spring 18 pulls the contact arm 5 (with the pivot 10 and therewith the latch 3 with its pins 11) downwardly in the opening direction 28 until the stop 19 under the pivot 10 is engaged and the stop 21 under the hooked part 27 is engaged. The torsion spring 17, which applies a clockwise turning moment to the lever 2, has the effect that the guide surfaces 9 press against the pins 11 so as to lift the latch 3 over the keeper 4. Thereupon, the circuit breaker is ready to be once again manually switched-on as soon as the keeper 4 has been pivoted-back into its normal position according to Figures 1 and 2.

Figure 4 shows a perspective view of the manually operated actuator lever (1,2). At the edges of the sides 30 of the fork of the lever 2, there is provided the guide surfaces 9 having the arcuate recesses in which the pins 11 can be received.

In an alternative arrangement, when the hooked part 27 is engaged by the pins 11 of the latch 3, a plunger-type or impact-type armature (not shown) acting on the hooked part 27 is able to open the contacts 6,7 prior to unlatching the circuit breaker. With this arrangement, it is advantageous if the tension spring 18 so engages at the contact arm 5 with regard to the pivot 10 that, on rotation of the contact arm 5 in the opening direction, the lever arm relative to the pivot 10 is shortened and the spring remains substantially unlengthened. Thereby, the open ing travel is promoted whilst the countertorque is reduced.

WHAT WE CLAIM IS: 1. An automatic circuit breaker including a manually operable actuator, a latch, and a contact arm connected to the latch and carrying a contact and being movable between "on" and "off" positions of the circuit breaker in which said contact respectively engages with and disengages from a further contact, in which: the actuator is pivotally mounted and has a handle portion by which the actuator may be manually manipulated and a forked portion which embraces said latch and said contact arm; guide surfaces are provided on said actuator and latching pins are provided on said latch to engage said guide surfaces so as to control the movement of the latch in dependence upon the movement of the actuator so that opening movement of the actuator is accompanied by disengaging movement of the contact arm and its contact from said further contact, and closing movement of the actuator is accompanied by engaging movement of the contact arm and its contact towards said further contact: and in which each latching pin engages a part of the corresponding guide surface, when the contact arm is in the "on" position of the circuit breaker, at which the normal to said part of the guide surface extends adjacent to but to one side of the pivotal axis of the actuator so that a torque is applied to the latch and to the contact arm effective to maintain the contact arm in the "on" position of the circuit breaker.

2. An automatic circuit breaker according to claim 1, in which the latch has a forked end to embrace the contact ann, and holds a pivot for the contact arm.

3. An automatic circuit breaker according to claim 1 or 2, in which the guide surfaces have arcuate recesses in which the latching pins are receivable to enable the disengaging movement of the latch and the contact arm when the actuator carries out its opening movement.

4, An automatic circuit breaker according to claim 2 or claim 3, when appendant to claim 2, in which the contact arm has a hooked part which is located on one side of the pivot for the contact arm and said contact is located on the other side of said pivot, the hooked part being engageable by the latching pins so as to apply a turning moment to the contact arm about said pivot in order to increase the separating force applied to said contact to disengage the latter from said further contact when the actuator carries out its opening movement.

5. An automatic circuit breaker according to claim 4, in which a spring engages said contact arm at a position between said latching pins and said pivot and acts to apply a force to the contact arm which (a) applies a torque to the contact arm about its pivot so as to maintain the contact in engagement with said further contact in the "on" position of the circuit breaker and (b) which urges the contact arm and the latch to carry out disengaging movement when the actuator carries out its opening movement.

6. An automatic circuit breaker according to claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ing travel is promoted whilst the countertorque is reduced. WHAT WE CLAIM IS:

1. An automatic circuit breaker including a manually operable actuator, a latch, and a contact arm connected to the latch and carrying a contact and being movable between "on" and "off" positions of the circuit breaker in which said contact respectively engages with and disengages from a further contact, in which: the actuator is pivotally mounted and has a handle portion by which the actuator may be manually manipulated and a forked portion which embraces said latch and said contact arm; guide surfaces are provided on said actuator and latching pins are provided on said latch to engage said guide surfaces so as to control the movement of the latch in dependence upon the movement of the actuator so that opening movement of the actuator is accompanied by disengaging movement of the contact arm and its contact from said further contact, and closing movement of the actuator is accompanied by engaging movement of the contact arm and its contact towards said further contact: and in which each latching pin engages a part of the corresponding guide surface, when the contact arm is in the "on" position of the circuit breaker, at which the normal to said part of the guide surface extends adjacent to but to one side of the pivotal axis of the actuator so that a torque is applied to the latch and to the contact arm effective to maintain the contact arm in the "on" position of the circuit breaker.