CN1041971C - An electro-magnetic device - Google Patents
An electro-magnetic device Download PDFInfo
- Publication number
- CN1041971C CN1041971C CN94102497A CN94102497A CN1041971C CN 1041971 C CN1041971 C CN 1041971C CN 94102497 A CN94102497 A CN 94102497A CN 94102497 A CN94102497 A CN 94102497A CN 1041971 C CN1041971 C CN 1041971C
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- Prior art keywords
- core rod
- mandrel
- pole piece
- circuit breaker
- cavity
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- 239000007788 liquid Substances 0.000 claims abstract description 9
- 238000013016 damping Methods 0.000 claims abstract description 4
- 230000007246 mechanism Effects 0.000 claims description 9
- 230000006835 compression Effects 0.000 claims 1
- 238000007906 compression Methods 0.000 claims 1
- 238000002360 preparation method Methods 0.000 claims 1
- 230000004907 flux Effects 0.000 description 8
- 230000001133 acceleration Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
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Abstract
The present invention relates to an electromagnetic operating device 12 for a breaker 10, which comprises a coil 13, wherein the coil 13 determines a hollow cavity. A first core rod 14 and a second core rod 16 are arranged in the hollow cavity and are adjacent to each other. The first core rod 14 is arranged in a hermetic container 18, and liquid performs a damping function is filled in the hermetic container 18. The first core rod 14 can move in the container 18 in the mode of being damped; the second core rod 16 can also move in the hollow cavity, and the motion of the second core rod 16 is guided by an opening pipe 20. The first core rod 14 and the second core rod 16 are respectively pushed away from a pole shoe 30 of the device 12 by spiral springs 32 and 34.
Description
The invention relates to an electromagnetic actuating device for a circuit breaker.
French patent application No. 2246052 discloses an electromagnetic operating device for a circuit breaker comprising a pair of armatures or core rods arranged coaxially with one another and slidable in a cavity of a coil. The coil is surrounded by a magnetic wheel. The armatures are movable relative to the coil, and each of the armatures acts on a trip mechanism that is operable to release a movable circuit-breaking contact element of the circuit breaker. With the coaxially arranged mandrel, independent rotation of the mandrel is not possible.
It is an object of the present invention to provide an electromagnetic operating device for a circuit breaker that facilitates independent rotation of a core rod, thereby providing more accurate trip characteristics.
According to the present invention, there is provided an electromagnetic operating device for a circuit breaker, the operating device comprising:
a coil defining a cavity;
a first mandrel disposed within the cavity, the mandrel being movable within the cavity in a damped manner between a first normal position and a second position;
a first advancing means for advancing the first core rod from its second position to its first position;
a second mandrel disposed within the cavity and movable within the cavity between a first position, a normal position, and a second position;
a second advancing means for advancing a second mandrel from its second position to its first position; wherein,
the first core rod and the second core rod are arranged adjacent to each other in the cavity;
a magnetic circuit determining device arranged in the vicinity of at least a part of the coil, the magnetic circuit determining device comprising a pole piece, a stator support and an armature movably arranged relative to the stator support, the pole piece and the two core rods being arranged in the following manner: the air gap between the first core rod and the pole piece in the normal position is smaller than the air gap between the second core rod and the pole piece in the normal position, and each core rod is closer to the pole piece in the second position than in the respective first normal position.
The first mandrel may be contained in a sealed container containing a liquid for slowing the movement of the first mandrel.
The first and second urging means may be compressed coil springs, each spring being disposed between its respective core rod and pole piece.
The coil may be circular or elliptical.
The armature may be pivotally disposed relative to the stator support, and the armature may be coupled to a trip mechanism of the circuit breaker.
An air gap may be defined between the stator support and the pole shoe, and a second core rod may then be disposed in the cavity on the side of the air gap between the pole shoe and the stator support.
Those skilled in the art will appreciate that the two core rods in their first position have a portion disposed outside of the stator support, and thus the stator support may need to define two openings. One opening for a first core rod and the other for a second core rod; two mandrels project through the two openings.
The two core rods can be moved towards the pole shoe when moving from their first position to their second position, and can abut against the pole shoe when the core rods are in their second position.
The end of the second core rod remote from the pole shoe may be provided with a coupling piece for mechanically coupling the second core rod to the movable contact base of the circuit breaker. The connecting piece is an idle stroke connecting piece, and the movable contact seat can move independently of the second core rod, and the second core rod can also move independently of the movable contact seat within a preset range. The movable contact block is movable between an "on" position in which the circuit breaker electrical path is on and an "off" position in which the circuit breaker electrical path is off. The idle stroke link can thus have the effect that: when the movable contact base is in the "on" position, the second core rod can move from the first position to the second position under the condition that the movable contact base is not moved; when the second mandrel is in its first position, the movable contact base can move from its "on" position to its "off" position without changing the position of the second mandrel.
When current flows through the coils, a magnetic flux is generated in each core rod, the magnitude of which is inversely proportional to the air gap between the core rod and the pole piece. The force produced by the magnetic flux acting on the core rod in the direction of the pole shoes against the corresponding compressed spring is proportional to the square of the magnetic flux.
Accordingly, it can also be appreciated that if a first, relatively small predetermined current is passed through the coil, the force acting on the first core rod tends to move the first core rod in the direction of the pole piece. The first core rod is larger than the second core rod because the air gap between the first core rod and the pole piece is smaller than the air gap between the second core rod and the pole piece in the absence of current. The movement of the first mandrel within its housing is slowed by the liquid within the vessel, the degree of which is determined by several factors, including the viscosity of the liquid. When the first core rod reaches the pole piece, the reluctance of the magnetic circuit formed by the armature, a portion of the stator support and pole piece, and the first core rod is significantly reduced, thereby increasing the electromagnetic force acting on the pivoted armature, which is of sufficient magnitude to bring the armature into contact with the stator support and pole piece, thereby tripping the circuit breaker.
In medium or heavy overload, i.e. when the current is significantly greater than the first current, the force on the first mandrel is greater than the force on the second mandrel, but the closing speed of the first mandrel is significantly slower than that of the second mandrel due to the slowing of the liquid. The force on the second mandrel is of a magnitude sufficient to compress a spring associated with the second mandrel, which is moved almost instantaneously into contact with the pole piece. Due to the action of the relatively large current, the armature is attracted to the pole shoe, tripping the circuit breaker even before the second core rod is completely closed. When the armature is closed, the reluctance of the magnetic circuit through the second core rod is reduced, causing a sharp increase in the magnetic flux therein, further accelerating the movement of the second core rod.
Because the movable contact seat and the second core rod are connected by the unloaded stroke connecting piece, the second core rod can not start the movement of the contact seat when starting to move in an accelerated way. The armature closes almost immediately and in any case before the second core rod has moved to a position sufficient to bring the link. Although the armature is closed, the movable contact base is closed even though the armature is closed due to the inherent time delay of the tripping mechanism. However, when the armature is closed, the magnetic resistance is significantly reduced and the second core rod moves with a greater acceleration. Accordingly, the movable contact block is also moved extremely rapidly to the open position.
The high-speed opening of the moving contact block in the event of a short circuit gives the electrical circuit a high resistance which limits the current flow and the clearing time.
By proper matching of the initial air gaps of the spring and the core rod, the following properties can be achieved:
the precise trip point and typical time delay of a liquid-magnetic circuit breaker;
a positive, accurate and easily preset instantaneous trip independent of the delay of the damped first mandrel;
effective acceleration of the moving contact block during a short circuit, which may provide proper current limiting; and
the possibility of contact sticking during overload is significantly reduced.
The invention also extends to a circuit breaker comprising an electromagnetically operated device as described above.
In use, the coil of the electromagnetic operating device may carry the load current of the circuit breaker.
The invention will now be illustrated with reference to the following figures:
fig. 1 is a schematic sectional view of a part of a circuit breaker employing an electromagnetically operated device of the present invention. The circuit breaker is in a normal working state, the tripping mechanism is locked, and the movable contact base is closed;
fig. 2 is a further schematic cross-sectional view of the circuit breaker showing how the circuit breaker responds to moderate overload currents;
fig. 3 is a further schematic cross-sectional view of the circuit breaker, further illustrating how the circuit breaker responds to moderate overload currents;
fig. 4 is a further schematic cross-sectional view of the circuit breaker illustrating how the circuit breaker responds to severe overload currents; and
fig. 5 is a further schematic cross-sectional view of the circuit breaker further illustrating how the circuit breaker responds to severe overload currents.
Referring first to fig. 1 of the drawings, a portion of a circuit breaker is generally indicated by reference numeral 10. The circuit breaker 10 comprises an electromagnetically operated device 12 according to the invention. The operating device 12 comprises a coil 13 defining a cavity. A first mandrel 14 and a second mandrel 16 are disposed within the cavity, with the two mandrels adjacent. The first mandrel 14 is contained in a sealed container 18, and the container 18 is filled with a damping fluid. The mandrel 14 may move within the vessel 18 in a damped manner. The second mandrel 16 is also movable within the cavity, the movement of which is guided by an open tube 20.
The coil 13 is wound on a bobbin 22 defining a cavity, the coil 13 being circular or elliptical.
The bobbin 22 is mounted on an "L" shaped stator support 24, the stator support 24 having a base 26 and a post 28 extending from the base 26.
As can be seen in FIG. 1, container 18 passes through a first opening of column 28, and second mandrel 16 passes through a second opening of column 28.
One pole piece 30 is disposed on a side of the bobbin 22 opposite the post 28. An air gap 31 separates the pole piece 30 from the base 26 of the stator support 24. The first core rod 14 is urged away from the pole piece 30 by a first coil spring 32 and the second core rod 16 is urged away from the pole piece 30 by a second coil spring 34. The first mandrel 14 and the second mandrel 16 are segmented and have thinner ends that extend into springs 32 and 34, respectively. Note that one end 36 of first core rod 14 is closer to pole piece 30 than one end 38 of second core rod 16 when coil 13 is not energized. The air gap between the first core rod 14 and the pole piece 30 is smaller than the air gap between the second core rod 16 and the pole piece 30. Those skilled in the art will appreciate that coil 13 will, in use, generate a magnetic flux tending to move mandrels 14 and 16 toward the pole pieces against springs 32 and 34.
The circuit breaker 10 also has an armature 40 which is pivotally movable into contact with the free end of the post 28 and the upper end of the pole piece 30. The armature 40 is connected to the trip mechanism (not shown) of the circuit breaker 10 in a conventional manner.
Further, the circuit breaker 10 has a fixed contact 42 and a movable contact 44. The movable contacts 44 are carried by a movable contact base 46, the movable contact base 44 being movable between an on or "on" position in which the contacts 42 and 44 are both electrically and mechanically in contact with each other, and an off or "open" position in which the contacts 42 and 44 are separated from each other.
The movable contact block 46 is mechanically connected to the second mandrel 16 by a connecting rod 50. The connecting rod 50 is connected to the second mandrel 16 in an idle stroke manner, the second mandrel 16 defining an empty slot 52 therein. The connecting piece 50 has a predetermined length and the slot 52 is arranged such that the end of the connecting rod 50 connected to the second core rod is approximately in the center of the slot 52 when the movable contact block 46 is in its closed position and there is no current in the coil 13. Thus, if the second core rod 16 is in the non-energized position, the movable contact block 46 is free to move from its closed position to its open position, and when the movable contact block 46 is in the closed position, the second core rod 16 can move within a certain range toward the pole piece 30 without entraining the contact block 46.
Note that coil 13 carries the load current of circuit breaker 10.
Referring now to fig. 2 and 3, the manner in which the circuit breaker 10 responds to a medium-range load current is shown. Since the initial air gap between first core rod 14 and pole piece 30 is smaller than the air gap between second core rod 16 and pole piece 30, a moderate overload current will cause first core rod 14 to move toward pole piece 30. Because the movement of first core rod 14 is slowed by the liquid in container 18, it takes a predetermined amount of time for the first core rod to move into contact with pole piece 30 (shown in FIG. 2). The amount of time depends on a number of factors including the viscosity of the liquid and the magnitude of the overload current.
When the first core rod 14 abuts against the pole piece 30, the magnetic properties of the magnetic circuit formed by the armature 40, the column 28, the first core rod 14 and the pole piece 30 are significantly reduced, so that the electromagnetic force acting on the armature 40 is increased. The electromagnetic force may be large enough to move the armature into contact with the post 28 and pole piece 30 (as shown in fig. 3), thereby actuating the trip mechanism of the circuit breaker 10. The trip mechanism acts on the contact block 46 to move it from the closed position to the open position (as shown in figure 3). The second mandrel 16 remains substantially in its first, normal position because the current is not sufficient to move the second mandrel a significant distance. However, due to the no-load stroke characteristic of the connecting rod 50 and the slot 52, the movable contact 46 can move from its closed position to its open position (as shown in fig. 3).
Referring now to fig. 4 and 5, the manner in which the circuit breaker 10 responds to severe overload currents is illustrated.
When the overload current is sufficiently high, the force on second core rod 16 is sufficient to move it into contact with pole piece 30. It will be appreciated that although initially the force on first mandrel 14 is greater than the force on second mandrel 16, second mandrel 16 will be closer to pole piece 30 than first mandrel 14 due to the damping effect of the liquid in vessel 18. When this occurs, the magnetic flux through the second mandrel 16 will be greater than the magnetic flux through the first mandrel 14, and thus the force on the second mandrel 16 will be greater than the force on the first mandrel 14, since the magnetic flux is inversely proportional to the air gap.
Further, because the overload current is very high, the armature 40 will move into contact with the post 28 and the pole piece 30 before the second core rod 16 contacts the pole piece 30 (as shown in FIG. 4), and the trip mechanism is therefore essentially instantaneous.
It will be appreciated that when the movable contact block 46 is in the closed position, the second core rod 16 is accelerating toward the pole piece 30. The slot 52 and the connecting rod 50 are designed such that the connecting rod 50 will reach the end of the cavity 52 before the second core rod 16 reaches the end of its travel, so that continued movement of the second core rod 16 towards the pole piece 30 will cause the contact block 46 to move away from the stationary contact 42 (as shown in fig. 4). When the second core rod 16 reaches the pole piece 30, the contact block 46 is also free to move toward the fully open position, at which time the connecting rod 50 will move within the slot 52.
The high speed opening of the moving contact block 46 in the presence of a large overload current causes the electrical circuit to have a high resistance that limits the current through and clearing time of the circuit breaker 10.
Those skilled in the art will appreciate that the characteristics of circuit breaker 10 will vary with the strength of springs 32 and 34 and the air gap between mandrels 14 and 16 and pole piece 30.
The invention thus has the advantage that the following can be achieved:
accurate trip point and typical time delay of a liquid-magnetic circuit breaker:
a forward, accurate and easily pre-adjusted instantaneous trip independent of the delay of the damped first mandrel;
effective acceleration of the moving contact block during a short circuit, which may provide proper current limiting; and
the possibility of contact sticking during overload is significantly reduced.
Claims (9)
1. An electromagnetic operator (12) for a circuit breaker (10), the operator (12) comprising:
a coil (13) defining a cavity;
a first mandrel (14) disposed within the cavity, the first mandrel (14) being movable in a damped manner within the cavity between a first, normal position and a second position;
a first advancing means (32) for advancing the first mandrel (14) from its second position to its first position;
a second mandrel (16) disposed within the cavity and movable within the cavity between a first, normal position and a second position;
a second advancing device (34) for advancing the second mandrel (16) from its second position to its first position; it is characterized in that the preparation method is characterized in that,
a first mandrel (14) and a second mandrel (16) are disposed adjacent to each other in the cavity;
a magnetic circuit defining device arranged adjacent at least a portion of the coil (13), the magnetic circuit defining device comprising a pole piece (30), a stator support (24) and an armature (40) movably arranged relative to the stator support (24), the pole piece (30) and said core rods (14, 16) being arranged such that the air gap between the first core rod (14) and the pole piece (30) in its normal position is smaller than the air gap between the second core rod (16) and the pole piece (30) in its normal position, and such that the second position of each core rod (14, 16) is closer to the pole piece (30) than the first, normal position of each core rod (14, 16).
2. Electromagnetic operating device for circuit breaker according to claim 1, characterized in that the first core rod (14) is contained in a sealed container (18), the container (18) being filled with a liquid for damping the movement of the first core rod (14).
3. Electromagnetic operating device for circuit breakers according to claim 1 or claim 2, characterized in that the first and second thrusting means (32, 34) are both helical springs under compression, each spring (32, 34) being arranged between its respective core rod (14, 16) and pole shoe (30).
4. Electromagnetic operating device for circuit breakers according to claim 1, characterized in that the coil (13) is circular or elliptical.
5. Electromagnetic operating device for circuit breaker according to claim 1, characterized in that the armature (40) is arranged in a pivotal manner with respect to the stator support (24), the armature (40) being connectable to a trip mechanism of the circuit breaker (10).
6. Electromagnetic actuating device for circuit breakers according to claim 5, characterized in that between the stator support (24) and the pole shoe (30) an air gap (31) is defined.
7. Electromagnetic actuating device for circuit breakers according to claim 6, characterized in that the second core rod (14) is located in the cavity on the side where there is an air gap (31) between the pole piece (30) and the stator frame (24).
8. The electromagnetic actuating device for circuit breakers according to claim 5, characterized in that the stator support (24) defines two openings, one for the first core rod (14) and one for the second core rod (16), through which the two core rods (14, 16) pass.
9. An electromagnetic actuating device for circuit breaker according to claim 1, characterized in that the end of the second core rod (16) remote from the pole piece (30) is provided with a connecting rod (50) for mechanically connecting the second core rod (16) to the movable contact block (46) of the circuit breaker (10), the connecting rod (50) being an idle stroke connecting rod, so that the movable contact block (46) can move independently of the second core rod (16), the second core rod (16) being movable independently of the movable contact block (46) within a predetermined range.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102497A CN1041971C (en) | 1994-02-28 | 1994-02-28 | An electro-magnetic device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102497A CN1041971C (en) | 1994-02-28 | 1994-02-28 | An electro-magnetic device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1107606A CN1107606A (en) | 1995-08-30 |
| CN1041971C true CN1041971C (en) | 1999-02-03 |
Family
ID=5030685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94102497A Expired - Fee Related CN1041971C (en) | 1994-02-28 | 1994-02-28 | An electro-magnetic device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1041971C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100392787C (en) * | 2005-07-26 | 2008-06-04 | 陈景正 | Electromagnetic breaker tripping mechanism |
| CN101894713A (en) * | 2009-05-21 | 2010-11-24 | 上海良信电器股份有限公司 | Movement mechanism of magnetic loop in hydraulic electromagnetic type breaker |
| AT511791A2 (en) * | 2011-08-12 | 2013-02-15 | Eaton Gmbh | SHUTTER FOR A PROTECTION SWITCH |
| CN103515162A (en) * | 2012-06-18 | 2014-01-15 | 北京人民电器厂有限公司 | Miniature circuit breaker |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3914720A (en) * | 1973-09-27 | 1975-10-21 | Siemens Ag | Automatic protective circuit breaker |
| GB2117973A (en) * | 1982-04-06 | 1983-10-19 | Matsushita Electric Works Ltd | Circuit protecting sensor |
-
1994
- 1994-02-28 CN CN94102497A patent/CN1041971C/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3914720A (en) * | 1973-09-27 | 1975-10-21 | Siemens Ag | Automatic protective circuit breaker |
| GB2117973A (en) * | 1982-04-06 | 1983-10-19 | Matsushita Electric Works Ltd | Circuit protecting sensor |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1107606A (en) | 1995-08-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 19990203 Termination date: 20100228 |