Multi-pole molded case circuit breaker with a safety device

Abstract

The present invention relates to a multi-pole molded case circuit breaker, more particularly, to a multi-pole molded case circuit breaker having a safety device (with an isolation function) which prevents a manipulation handle from being moved to an off-position when a fusion occurs on a contact part.

Claims

1. A multi-pole molded case circuit breaker, including a fixed contact, a movable contact configured to be in contact with and separated from the fixed contact and shafts to which the movable contact is fixed, an open/close device configured to operate one of the shafts, and a shaft pin configured to connect the shafts, the multi-pole molded case circuit breaker comprising: a lower link having an indicator at one surface thereof; and a locking plate, rotatably mounted to a side plate, configured to allow or release movement of the handle to an OFF-position by being in contact with the indicator, wherein the locking plate includes a lever restriction part configured to restrict an open/close lever coupled to the handle, and wherein the open/close lever includes a blocking protrusion, and the lever restriction part includes a restriction protrusion configured to be caught by the blocking protrusion, wherein the locking plate includes: a rotation prevention part formed in a predetermined length in line with inclination of the shaft pin and configured to restrict movement of the handle to an OFF-position by being in contacting with the indicator; and a rotation permission part, formed at one side of the rotation prevention part, configured to permit the handle to move to an OFF-position by being released from contact with the indicator, and wherein the length of the rotation prevention part is larger than displacement of inclination of the shaft pin.

2. The multi-pole molded case circuit breaker of claim 1, wherein the rotation prevention part is formed in a slit.

3. The multi-pole molded case circuit breaker of claim 1, wherein the rotation permission part comprises a hole.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments and together with the description serve to explain the principles of the invention.

(2) In the drawings:

(3) FIG. 1 is a longitudinal sectional view illustrating a base mold of a multi-pole molded case circuit breaker, according to a conventional art;

(4) FIG. 2 is a perspective view of FIG. 1, with the base mold excluded;

(5) FIG. 3 is a disassembled perspective view illustrating parts including a handle of FIG. 2;

(6) FIG. 4 is a conceptual view illustrating a bending phenomenon of a shaft pin of a multi-pole molded case circuit breaker, according to a conventional art;

(7) FIG. 5 is a partial perspective view illustrating a multi-pole molded case circuit breaker, according to one embodiment of the present invention;

(8) FIG. 6 is a disassembled perspective view illustrating an open/close device of a multi-pole molded case circuit breaker, according to one embodiment of the present invention;

(9) FIG. 7 is a perspective view illustrating a locking plate applied to a multi-pole molded case circuit breaker, according to one embodiment of the present invention;

(10) FIG. 8 is a perspective view illustrating a lower link applied to a multi-pole molded case circuit breaker, according to one embodiment of the present invention;

(11) FIG. 9 is a perspective view illustrating an open/close lever applied to a multi-pole molded case circuit breaker, according to one embodiment of the present invention; and

(12) FIGS. 10 through 15 are views illustrating an ON-state, an OFF-state, a blocking state, a blocking released state, a trip state, and a contact fusing state of a multi-pole molded case circuit breaker, according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(13) Hereinafter, a preferred embodiment of a door interlock device for a power transformer room in accordance with an embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

(14) Referring to FIGS. 5 through 9, the multi-pole molded case circuit breaker, according to one embodiment of the present invention includes a fixed contact 20, a movable contact 25 configured to be in contact with and separated from the fixed contact 20 and a shaft 30 to which the movable contact 25 is fixed, an open/close device configured to operate the shaft 30, and a shaft pin 31 configured to connect the shafts 30, a lower link 40 having an indicator 41 at one surface thereof; and a locking plate 50, rotatably mounted to a side plate 45, configured to allow or release movement of the handle 27 to an OFF-position by contact with the indicator 41, wherein the locking plate 50 includes a rotation prevention part 51 formed in a predetermined length in line with inclination of the shaft pin 31 and configured to restrict movement of the handle 27 to an OFF-position by contacting with the indicator 41; and a rotation permission part 52, formed at one side of the rotation prevention part 51, configured to permit the handle 27 to move to an OFF-position by being released from contact with the indicator 41.

(15) According to a multi-pole molded case circuit breaker according to one embodiment of the present invention, includes a fixed contact 20 and a movable contact 25 configured to open or close a circuit by being in contact with or separated from the fixed contact 20 by each phase. The movable contact 25 is provided to a shaft 30 which is provided in each phase and configured to move according to rotation of the shaft 30. And a shaft pin 31 penetrating through the shaft 30 is provided to convey a rotational force of an open/close device to each shaft 30.

(16) The open/close device includes a toggle link device and a release device which are mounted on a pair of side plates 39. The toggle link device includes a handle 27 and an open/close lever 28 connected to the handle 27 and configured to rotate to ON-OFF positions, and an upper link 35 and a lower link 40 which are connected via a link shaft 38. The upper link 35 is rotatably mounted by a latch 33 and the lower link 40 is rotatably mounted by a shaft pin 31. Here, the open/close lever 28 includes a blocking protrusion 28a at its inner surface.

(17) The lower link 40 includes a shaft hole 40a through which a link shaft 38 is inserted and a pin hole 40b through which the shaft pin 31 is inserted, at its upper and lower ends, respectively. At the center of the lower link 40, an extended surface 40c, on which an indicator 41 is provided, is formed.

(18) The release device includes a latch 33 of the lever type, a latch holder 34 configured to restrict the latch 33, a cross bar 36 and a nail 37 which are configured to move by interworking with an overcurrent release device (not shown), and the latch 33 is released when the cross bar 36, the nail 37 and the latch holder 34 are moved by the overcurrent release device.

(19) Further, between the open/close lever 28 and the link shaft 38 of the toggle link device, a main spring 29 is disposed to maintain the force in the ON-OFF states.

(20) A locking plate 50 is rotatably mounted to a latch shaft 32. The locking plate 50 may be formed in a flat plate and includes a latch shaft hole 55 through which the latch shaft 32 is inserted at one side thereof and a rotation prevention part 51 and a rotation permission part 52 at another side thereof. Further, the locking plate 50 includes a lever restriction part 53 at its one side.

(21) The rotation prevention part 51 may be formed in a slit (a sliding hole) of a predetermined length. The indicator 41 of the lower link 40 may be slidably inserted into the rotation prevention part 51. Here, the length of the rotation prevention part 51 may be preferably set to be larger than an inclination displacement, considering an inclination (bending) of the shaft pin 31. When the handle 27 is in an ON-state, the shaft 30 is rotated in an anticlockwise direction, and the indicator 41 is located at a lower part of the rotation prevention part 51. When the movable contact 25 is fused into the fixed contact 20 so that the shaft 30 is insufficiently rotated, the indicator 41 may not be escaped from the rotation prevention part 51 even though the handle 27 is arbitrarily rotated.

(22) The rotation permission part 52 is a part to permit the shaft 30 to rotate. In a case where the movable contact 25 and the fixed contact 20 are not fused, the shaft 30 may be freely rotated so that the indicator 41 may be escaped from the rotation prevention part 51 and then moved into a region of the rotation permission part 52.

(23) The rotation prevention part 51 and the rotation permission part 52 may be formed in single hole.

(24) The lever restriction part 53 may be formed in a hole. The lever restriction part 53 may be a space where the blocking protrusion 28a of the open/close lever 28 is moved. The lever restriction part 53 includes a restriction protrusion 53a with which the blocking protrusion 28a contacts. When the indicator 41 is in contact with a connection spot of the rotation prevention part 51 and the rotation permission part 52, the blocking protrusion 28a is caught by the rotation restriction protrusion 53a, thereby limiting rotation of the open/close lever 28. In this instance, the handle 27 can not move to an OFF-position. When the indicator 41 approaches to the rotation permission part 52 after passing through the rotation prevention part 51, the blocking protrusion 28a is released from the restriction protrusion 53a, thereby permitting the open/close lever 28 to rotate. In this instance, the handle 27 may move to an OFF-position.

(25) FIGS. 10 through 15 are views illustrating an ON-state, an OFF-state, a blocking state, a blocking released state, a trip state, and a contact fusing state of a multi-pole molded case circuit breaker, according to one embodiment of the present invention.

(26) Hereinbelow, an open/close operation of the multi-pole molded case circuit breaker, according to one embodiment of the present invention will now be described.

(27) When the handle 27 is manipulated to move to an OFF-state in a closing state (ON), as shown in FIG. 10, the upper link 35 and lower link 40 of the toggle link device rotate the shaft 30, while being bent in a > shape by an elastic force of the main spring 28, so that the movable contact 25 is separated from the fixed contact 20, thereby opening the circuit, as can be seen in FIG. 11.

(28) Referring to FIGS. 12 and 13, an intermediate state between an ON-state and an OFF-state will be described.

(29) While the handle 27 is rotated at a certain range, the indicator 41 passes through the rotation prevention part 51, and in this state when a force applied to the handle 27 is removed, the handle 27 returns to an ON-position without moving to an OFF-state, and thus the movable contact 25 returns to an original position to contact with the fixed contact 20. When the handle 27 is sufficiently rotated, the indicator 41 enters into the rotation permission part 52 after passing through the rotation prevention part 51. In this instance, the blocking protrusion 28a is released from the restriction protrusion 53a so that the handle 27 may move to an OFF-position.

(30) Referring to FIG. 14, when an overcurrent flows in a conductive state and as a result, an overcurrent release device (not shown) is operated, the cross bar 36 and nail 37 are operated by the output thereof to release the latch 33 which is caught by the latch holder 34. As a result, the latch 33 is rotated in an anticlockwise direction and an open/close device is tripped to open the movable contact 25, thus cutting off a current flow. Further, the handle 27 is moved by the trip operation to an intermediate position between an ON-position and an OFF-position together with the open/close lever 28 to indicate the trip operation. Further, when the circuit breaker is reclosed after the trip operation, the release devices 33, 34, 36 and 37 are reset by moving the handle 27 to an OFF-position and then moving to an ON-position, the movable contact 25 is closed.

(31) Referring to FIG. 15, when the fixed contact 20 and the movable contact 25 are fused due to an abnormal current flowing through a main circuit in a state that the contacts of a main circuit are closed, the movable contact 25 is not opened or closed even though an overcurrent release device (not shown) is normally operated, and contacts of the main circuit are maintained in a contact state. In this instance, since the indicator 41 is not escaped from the rotation prevention part 51 even though a user moves the handle 27 to an OFF-position, the blocking protrusion 28a is caught by the restriction protrusion 53a so that the handle 27 is not rotated any more to an OFF-position. In this instance, though a displacement of the shaft pin 31 occurs due to an inclination of each phase, movement of the handle 27 is restricted unless the handle 27 is rotated more than a range set by the rotation prevention part 51. That is, since length of the rotation prevention part 51 is formed larger than a displacement of the shaft pin 31 which is set by an inclination between each phase, an operation of the indicator 41 due to fusion of contacts is not included in a rotation permission range of the handle 27. That is, there is an advantage in that an isolation function is operated by compensating for displacement of the shaft 30 due to an inclination (bending) of the shaft pin 31.

(32) In accordance with one embodiment of the present invention, there is provided an effect in that it is possible to restrict the manipulation handle to move to an OFF-position in a state that contacts of the main circuit are fused by an abnormal current.

(33) Further, there is also an advantage in that an isolation function is not released within a predetermined range of gap by compensating for inclination of a shaft pin.

(34) As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.