Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Reexamination Certificate
2000-11-27
2001-07-17
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
C335S006000, C335S172000
Reexamination Certificate
active
06262643
ABSTRACT:
The subject of the present invention is a mechanism for operating an electric circuit breaker.
An electric circuit breaker is aimed at protecting an electrical installation by opening an electric circuit when a fault is detected, when there is overload or a rise in temperature, this opening of the circuit being achieved via an electromagnetic trip and/or a thermal trip, depending on the type of fault observed. In general, circuit breakers react firstly to an electromagnetic trip and, secondly, to a thermal trip.
The circuit breaker concerned here, is of the type comprising an insulating casing inside which are mounted:
a contact mounted fixedly in the casing,
a contact mounted in a support, pivoting in the casing between a closed position and an open position in which the two contacts are apart,
a pivoting manual operating knob, mounted articulated on the casing, and to which is articulated one end of a link rod, the other end of which is mounted, with the possibility of pivoting, on a pivoting pawl, so as to form a toggle lever system collaborating with the support for the mobile contact so as to close or not close the contacts, according to the position of the toggle lever system,
elastic means for, on the one hand, closing the contacts and, on the other hand, opening them, according to the position of the toggle lever system,
a trip element mounted so that it can pivot on the casing and subjected to the action of elastic return means returning it to a basic position from which it can be moved away by electromagnetic and/or thermal circuit-breaking means, so as to actuate the toggle lever system in a direction for opening the contacts.
The object of the invention is to provide a circuit breaker of this type, the control mechanism of which is of a simple structure, reacts very quickly, has good reliability, including if the contacts are slightly welded together as a result of heating, and which has excellent safety properties, in particular not being resettable as long as the thermal trip is in the detection position, or not allowing the circuit breaker to be held manually in a semi-closed position by manually holding the operating knob in an intermediate position.
To this end, in the control mechanism to which it relates:
the pawl is mounted so that it can pivot on the support for the mobile contact about an axle located near the end of this support which is the opposite end to the end equipped with the mobile contact part intended to rest against the fixed contact, and
the trip element consists of a part in the overall shape of a L, one of the branches of which is intended to be actuated by the circuit-breaking means, and the other branch of which is equipped with a ramp, of which the surface facing the outside of the L is intended to rest under a complementary ramp, that the pawl has, to keep the toggle lever system and thus the support for the mobile contact in a position in which the contacts are closed.
When the circuit breaker is in the closed position, the toggle lever system is in a certain position. When the trip element is actuated by a circuit-breaking means, the ramp of the trip element lifts the ramp of the pawl, causing the latter to pivot to “break” the toggle lever system and cause it to move into its position corresponding to the circuit breaker being open. As soon as the toggle lever system has moved past its neutral point, the mobile contact pivots into the open position under the action of a spring.
Advantageously, the support for the mobile contact has the shape of a stirrup piece, that is to say comprises a central cavity in which the mobile contact is engaged, the end of the contact which is the opposite end to the end intended to rest against the fixed contact, being rounded so as to pivot in the, also rounded, bottom of the central cavity, the contact having, on its surface facing the fixed contact, a cut-out for the passage of the axle that articulates its support to the casing and a nose which, located between the axle of rotation of the support on the casing and the axle articulating the pawl to the support, serves for attaching a tension spring, the other end of which is fixed to the casing on the same side as the fixed contact with respect to the support for the mobile contact.
It must be noted that as the spring acts on the mobile contact and as the mobile contact is itself mounted with play inside its support, a slight shear movement of the mobile contact with respect to the fixed contact occurs upon the command to open the circuit breaker, making the opening conditions easier, especially if, under the action of previous heating, the two contacts have become slightly welded together. Furthermore, the location of the spring associated with the mobile contact allows this spring to act both in a direction for closing the contacts and also in a direction for opening the circuit breaker as soon as the toggle lever system has been “broken” and as soon as the support for the mobile contact can pivot.
According to another feature of the invention, the link between the link rod and the pawl is achieved by a curved end of the link rod engaged in a cavity in the pawl, this cavity being open on the side opposite the support for the mobile contact and comprising, towards the front and towards the rear, noses to allow the pawl to be actuated by the link rod in the direction for opening and in the direction for closing.
Under these conditions, as soon as the knob has been pivoted past the neutral point of the toggle lever system, the circuit breaker automatically switches to the tripped position under the action of the tension spring. This opening occurs even if the knob is not actuated towards its fully open position. This is a safety feature insofar as the circuit breaker can occupy just two stable positions, without the risk of an operator holding the knob in a semi-open position in which the mobile contact would be near to the fixed contact, as this would very soon lead to overheating and damage of the circuit breaker.
According to another feature of the invention, the pawl has, on one of its surfaces, a lug or the like, intended to rest against a post formed in the corresponding wall of the casing, to guide the pivoting of the pawl on the support for the mobile contact, when the circuit breaker is actuated.
Advantageously, the second branch of the trip element is placed between an electromagnetic circuit-breaker coil and a thermal trip, of the bimetallic strip type, and comprises a finger used for direct actuation, by pushing, and a nose allowing actuation by pulling, using a slide secured to the thermal trip.
As a preference, in this case, the slide associated with the thermal trip has an arm which, when the circuit breaker is in the tripped position and the bimetallic strip system is deformed under the action of heat, lifts the link rod and prevents it from being coupled to the pawl. In this case, the link rod is kept raised by the arm of the slide, and cannot therefore enter the cavity in the pawl to allow coupling therewith.
REFERENCES:
patent: Re. 33400 (1990-10-01), Fujii et al.
patent: 4968863 (1990-11-01), Rezac et al.
patent: 5162765 (1992-11-01), DiVincenzo et al
patent: 2552930 (1985-04-01), None
Barrera Ramon M.
Entrelec S.A.
Oliff & Berridg,e PLC
LandOfFree
Mechanism for controlling an electrical circuit breaker does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mechanism for controlling an electrical circuit breaker, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mechanism for controlling an electrical circuit breaker will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2496398