Patent Application
20080122563
1. Field of the Invention
The present invention relates to a mould cased circuit breaker, and particularly, to an instantaneous trip mechanism for a mould cased circuit breaker which is capable of adjusting a trip current sensitivity using a simple mechanism and of fabricating a reliable mould cased circuit breaker supplying a constant trip current sensitivity according to products.
2. Background of the Invention
In general, a mould cased circuit breaker denotes one of electrical appliances which automatically breaks a circuit when an over current or short-circuit current is electrically generated on a circuit between a power source and an electrical load.
The mould cased circuit breaker roughly includes a terminal unit connected to a power source or electrical load, a fixed contact and a movable contact which are electrically connected to the terminal unit, a switching mechanism for switching (opening or closing) a circuit by moving the movable contact to a position at which it is contacted with the fixed contact or a position at which it is separated from the fixed contact, and an instantaneous trip mechanism for detecting (sensing) a large current when the large current greater than a normal current flows over the circuit to thus trigger the switching mechanism to be moved to a trip position for opening (switching on) the circuit.
The mould cased circuit breaker having such construction is typically used such that it is connected to the circuit to switch on/off the circuit between a power source and an electrical load or to break the circuit when an abnormal current is generated to thereby protect the electrical load and the circuit.
Unlike manually driving the switching mechanism to the switching position of the circuit, on the other hand, when an abnormal current is generated on the circuit, the mould cased circuit breaker senses the abnormal current generated to thus be moved to a position where the circuit is automatically broken. Such operation is referred to as a trip operation.
When a current corresponding to many times of a rated current flows over the circuit, an instantaneous trip function is required such that the mould cased circuit breaker senses it to instantaneously break the circuit (i.e., perform the trip operation).
The present invention relates to an enhanced mechanism for the instantaneous trip of the mould cased circuit breaker. An instantaneous trip mechanism of a mould cased circuit breaker according to the related art will now be described.
As illustrated in
A detailed construction of the instantaneous trip mechanism 160 according to the embodiment of the related art will now be explained with reference to
As illustrated in
The trip mechanism 160 according to the related art includes a shooter 163 one end of which has a locker arm 153a and another end of which is connected to the switching mechanism 140, a cross bar 164 rotated to a position to lock or unlock the shooter 163, and rotatable to a position for unlocking the shooter by a pushing by the operation unit 162a of the armature 162, and an adjusting dial 166 having a side surface which is implemented as a cam surface, for adjusting a trip current sensitivity of the instantaneous trip mechanism.
The trip mechanism 160 according to the related art further includes a first driving force transfer bar 165 having an upper end contacted with the cam surface 166a of the adjusting dial 166 and a lower end for transferring a driving force, and rotatable according to a displacement of a contact point on the cam surface 166a, the displacement resulting from the rotation of the adjusting dial 166; a second driving force transfer bar 168 rotatably installed at a position at which the upper end 162a of the armature 162 is contacted to thusly transfer the driving force from the first driving force transfer bar 165 to the armature 162; and a spring 167 upper end of which is supported by the first driving force transfer bar 165 and lower end of which is supported by the second driving force transfer bar 168 to thusly transfer the driving force from the first driving force transfer bar 165 to the second driving force transfer bar 168 and simultaneously to maintain a relative position between the adjusting dial 166 and the first driving force transfer bar 165 and a relative position between the second driving force transfer bar 168 and the armature 162 as a set (adjusted) position.
An upper surface of the adjusting dial 166 has a connection groove (not shown) for a screw driver to allow a user to adjust the trip current sensitivity of the mould cased circuit breaker. The side surface of the adjusting dial 166 is implemented as the cam surface 166a having a varying radius such that the first driving force transfer bar 165 which is contacted with the cam surface 166a is rotated according to a contacted position with the cam surface 166a.
The armature 162 is biased by a torsion spring (a reference numeral is not given therefor) disposed at its lower portion thus to receive an elastic force in a direction closer to the fixed electromagnet 161 . The upper end 162a of the armature 162 is stopped by the second driving force bar 168. Accordingly, the armature 162 can continuously be in a state of being spaced apart from the fixed electromagnet 161.
An operation for adjusting a trip current sensitivity of the instantaneous trip mechanism for the mould cased circuit breaker according to the related art having such construction will now be explained.
Sensitivity with respect to a trip current depends on a distance between the fixed electromagnet 161 and the armature 162. That is, a short distance therebetween obtains a high sensitivity, while a long distance therebetween obtains a low sensitivity. Therefore, upon adjusting the distance to be short, the trip mechanism becomes as sensitive as initiating the trip operation even when a normal current, namely, a current close to a rated current flows. Upon adjusting the distance to be long, the trip mechanism performs the trip operation only when a current considerably larger than the rated current flows over the circuit.
Thus, upon rotating the adjusting dial 166 in a clockwise direction to obtain a high sensitivity with respect to the trip current, the upper end of the first driving force transfer bar 165 is contacted with a position where the radius of the cam surface 166a is great and simultaneously the first driving force transfer bar 165 is rotated in the clockwise direction. Accordingly, the spring 167 is descended to release (unlock) the second driving force transfer bar 168 pushed. The second driving force transfer bar 168 is then rotated in the clockwise direction. Consequently, an elastic bias force of the torsion spring is applied to the armature 162 which is thereby moved closely toward the fixed electromagnet 161 by a distance corresponding to a distance that the second driving force transfer bar 168 has been rotated. Hence, the current sensitivity over the circuit by which the trip operation is initiated can be adjusted to be higher,
Contrarily, in order to obtain a low sensitivity with respect to the trip current, namely, to adjust the current on the circuit for initiating the trip operation to be much greater than the rated current, when rotating the adjusting dial 166 in the counterclockwise direction, the upper end of the first driving force transfer bar 165 is contacted with a position where the radius of the cam surface 166a is small and simultaneously the first driving force transfer bar 165 is rotated in the counterclockwise direction, Accordingly, the spring 167 is ascended to push the second driving force transfer bar 168. The second driving force transfer bar 168 is thereby rotated in a counterclockwise direction. Consequently, the armature 162 overcomes the elastic bias force of the torsion spring to thusly be moved away from the fixed electromagnet 161 by a distance corresponding to a distance that the second driving force transfer bar 168 is rotated. Hence, the current sensitivity over the circuit for initiating the trip operation can be adjusted to be lower, namely, to allow the armature 162 to be operated with respect to a great current over the circuit.
The trip operation of the instantaneous trip mechanism according to the related art will now be explained.
After adjusting the current over the circuit that the trip mechanism initiates the trip operation, namely, adjusting the trip sensitivity, if an abnormal current (e.g., a short-circuit current) is generated over the circuit as a large current corresponding to many times of the rated current, the fixed electromagnet 161 is magnetized by the large current to thereby generate a great magnetic attraction force. Here, the magnetic attraction force of the fixed electromagnet 161 is much greater than a brake force of the second driving force transfer bar 168 by the spring 167. Accordingly, the operation unit 162a of the armature 162 pushes out the second driving force transfer bar 168 and is rotated in the counterclockwise direction, thereby hitting the lower end of the cross bar 164. The cross bar 164 is then rotated in the clockwise direction by the hitting of the operation unit 162a of the armature 162. Accordingly, the locker arm is unlocked and thereby the shooter 163 is rotated to thereafter trigger the switching mechanism 140 of
The trip mechanism for the mould cased circuit breaker of the related art has a complex construction, and uses the elastic force of the spring 167 to maintain a gap between the fixed electromagnet 161 and the armature 162. Accordingly, when massively producing the mould cased circuit breaker, since the elasticity of the spring 167 is not constant, the gap between the fixed electromagnet 161 and the armature 162 may be different according to products even if the adjusting dial 166 is rotated by a predetermined angle. Therefore, it is disadvantageously difficult to fabricate a reliable mould cased circuit breaker having a constant current value for initiating the trip operation.
On the other hand, an arrangement for double installing a mould cased circuit breaker (i.e., a main mould cased circuit breaker) for switching and protecting a main circuit (i.e., an upper circuit close to a power source) and a mould cased circuit breaker (i.e., a sub mould cased circuit breaker) for switching and protecting a sub circuit (i.e., a lower circuit which is divided from the upper circuit to be close to an electrical load appliance) is frequently being used even in a power distribution line in home as well as in industries. In the circuit protecting arrangement for double installing the upper and lower circuits, assuming that trip sensitivities for the mould cased circuit breakers having the instantaneous trip mechanism have been adjusted to be about the same, the mould cased circuit breakers of the upper and lower circuits are tripped at the same time or even only the mould cased circuit breaker of the upper circuit is tripped, with respect to an abnormal current much greater than the rated current.
It is not preferable in view of priorities of circuit protection that the load appliance on the lower circuit is preferentially protected with respect to the abnormal current and then the upper circuit is protected. Therefore, the mould cased circuit breaker installed on the upper circuit is required so that the instantaneous trip could be delayed as compared to the mould cased circuit breaker installed on the lower circuit.
Therefore, an object of the present invention is to provide an instantaneous trip mechanism for a mould cased circuit breaker which is capable of adjusting a trip current sensitivity using a simple mechanism and of fabricating a reliable mould cased circuit breaker by supplying a constant sensitivity of the trip current.
Another object of the present invention is to provide an instantaneous trip mechanism for a mould cased circuit breaker, in a mould cased circuit breaker installed on an upper circuit, which capable of delaying an instantaneous trip.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided an instantaneous trip mechanism for a mould cased circuit breaker comprising: a fixed electromagnet for generating a magnetic force which is variable depending upon a current flowing on a circuit, an armature disposed to face the fixed electromagnet and rotatable to a position at which the mould cased circuit breaker is tripped by the magnetic force from the fixed electromagnet when a large current exceeding a normal current flows over the circuit; a spring for elastically biasing the armature in a direction of being separated from the fixed electromagnet; an adjusting dial member having a cam surface for adjusting a gap between the armature and the fixed electromagnet; and an adjusting bar having one end contacted with the cam surface of the adjusting dial member and the other end contacted with the armature, and rotatable to change the gap by pushing (pressurizing) the armature according to the position contacted with the cam surface of the adjusting dial member,
According to another object of the present invention, the instantaneous trip mechanism for the mould cased circuit breaker may further comprise a delay unit connected to the armature for delaying the instantaneous trip using a stationary inertia when a large current exceeding a normal current flows over the circuit.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
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 embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
wherein
wherein
Description will now be given in detail of the present invention, with reference to the accompanying drawings.
A preferred embodiments of an instantaneous trip mechanism for a mould cased circuit breaker according to the present invention will now be explained with reference to the accompanying drawings. The instantaneous trip mechanism for the mould cased circuit breaker according to the present invention may refer to a mould cased circuit breaker shown in
First,
As illustrated in
In
The instantaneous trip mechanism for the mould cased circuit breaker according to the present invention illustrated in
The armature 262 receives a moment which is changed in proportion to a tangent value of an angle between the spring 267 and the armature 262 based upon an elastic force of the spring 267. That is, the armature 262 receives the moment of a direction of being separated from the fixed electromagnet 261 (e.g., a clockwise direction in
For example, upon rotating the adjusting screw 268a in a clockwise direction by using a screw driver, the adjusting screw 268a is moved forward through the through hole in which the threaded portion is disposed. Accordingly, the angle between the spring 267 and the armature 262 becomes wider. The armature 262 thusly receives a great moment of a direction of being separated from the fixed electromagnet 261, namely, of the clockwise direction in
Now, an operation of adjusting a trip sensitivity of the instantaneous trip mechanism for the mould cased circuit breaker in accordance with the one embodiment of the present invention having such construction will now be explained with reference to
First, a screw driver is inserted into a screw driver inserting groove (not having a reference number designated) formed on a top surface of the adjusting dial 266, and then rotated in a clockwise direction. The one end 265a of the adjusting bar 265, as illustrated in
Contrarily, the screw driver is inserted into the screw driver inserting groove to be rotated in a counterclockwise direction. Then, the one end 265a of the adjusting bar 265, as illustrated in
A trip operation of the instantaneous trip mechanism for the mould cased circuit breaker in accordance with the one embodiment of the present invention will now be explained with reference to
After adjusting the current over the circuit for initiating the trop operation of the trip mechanism, namely, after adjusting the trip sensitivity, for example, when an abnormal current (e.g., short-circuit current) is generated on the circuit as a great current corresponding to several times of the rated current, the fixed electromagnet 261 is magnetized by the great current to thereby generate a great magnetic attraction force. Here, the magnetic attraction force of the fixed electromagnet 261 is much greater than the elastic force of the spring 267. Accordingly, the armature 262 is rotated in a counterclockwise direction in the drawing. The driving force transfer unit 264b of the cross bar 264 is then rotated in a clockwise direction by the pushing of the armature 262. The latch portion of the cross bar 264 is then released from the shooter 263. Thereafter, the shooter 263 triggers the switching mechanism 140 of
As illustrated in
In
The instantaneous trip mechanism for the mould cased circuit breaker according to the present invention illustrated in
The instantaneous trip mechanism for the mould cased circuit breaker according to the present invention may further include delay units 269 and 269a connected to the armature 262 and using a stationary inertia to delay an instantaneous trip when a great current exceeding a normal current flows on a circuit.
The delay units 269 and 269a include a spring element 269a one end of which is fixed to the armature 262 for charging an elastic energy when the armature 262 is rotated and then discharging the charged elastic energy after a certain time delay, and a weight 269 fixed to the other end of the spring element 269a for providing a stationary inertia force to the spring element when the armature is rotated thus to allow the spring element to charge the elastic energy and to discharge the elastic energy after a predetermined delay, the weight 269 rotatable together with the spring element 269a by the elastic energy of the spring element 269a.
Here, a passing recess 262b is provided at a position corresponding to an upper portion of the armature 262 to thus allow a rotational movement of the weight 269. Preferably, the spring element 269a is constructed as a plate spring, and more particularly of a thin stainless-steel plate.
The spring element 269a may be formed of a typical coil spring rather than the plate spring.
The weight 269 may constructed of a roughly hexahedral weight support member (for which a reference number is not designated), which may be formed of a synthetic resin, having a hole for inserting therein the other end of the spring element 268a and fixed and supported by a fixing unit such as and a rivet for fixedly supporting the inserted the other end of the spring element 269a, and a metallic weight member (not shown) fixedly supported by being inserted in the weight support member. A weight of the metallic weight member may be determined according to a delay time which is required such that a tripping time point of the mould cased circuit breaker installed on the main circuit could preferably be later than that of the mould cased circuit breaker installed on the sub circuit.
The weight 269 is disposed at a position facing a central driving force transfer unit of three driving force transfer units 264b of the cross bar 264 of
As illustrated in
As illustrated in
As illustrated in
The armature 262 is provided with a passing recess 262b to thus allow the rotational movement of the weight 269. The weight 269 passed through the passing recess 262b hits the driving force transfer unit 264b of the cross bar 264 to rotate the cross bar 264 in a clockwise direction in the drawing. Consequently, the mould cased circuit breaker, which has the instantaneous trip mechanism according to the another embodiment of the present invention and is installed on the main circuit close to the power source, performs the instantaneous trip operation later than the mould cased circuit breaker installed on the sub circuit close to the load. Here, the mould cased circuit breaker installed on the sub circuit denotes the mould cased circuit breaker having the typical instantaneous trip mechanism or the instantaneous trip mechanism according to the one embodiment of the present invention other than the instantaneous trip mechanism according to the another embodiment of the present invention.
As described above, the present invention can provide the instantaneous trip mechanism for the mould cased circuit breaker so as to effectively fabricate the instantaneous trip mechanism for the mould cased circuit breaker which is capable of simply adjusting the trip current sensitivity using the simple mechanism and fabricating a reliable mould cased circuit breaker by providing a constant trip current sensitivity for each of products.
In addition, upon double installing the mould cased circuit breakers at the main circuit close to the power source and the sub circuit close to the load, it is effective to obtain the instantaneous trip mechanism for the mould cased circuit breaker in the mould cased circuit breaker installed on the upper circuit (i.e., the main circuit) so as to perform the instantaneous trip with more delay as compared to the mould cased circuit breaker installed on the lower circuit (i.e., the sub circuit).
As the present invention may be embodied in several forms without departing from the spirit or essential 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 spirit and 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.
