CN219759505U - Thermomagnetic trip for circuit breaker and circuit breaker - Google Patents

Abstract

A thermomagnetic release for a circuit breaker and a circuit breaker. The thermomagnetic release includes: an actuation unit; a trip actuating member; bimetallic strips; a trip member translatable between a first position in which the trip member is retained against translation by a portion of the trip actuating member, and a second position in which the trip actuating member is disengaged from retaining the trip member upon movement of the trip actuating member, allowing the trip member to translate to the second position; and the tripping transmission piece is abutted with a part of the tripping piece and is configured to pivot along a first direction under the driving of the translation of the tripping piece from the first position to the second position, and is also configured to be abutted with the locking mechanism, and the locking mechanism of the circuit breaker is unlocked when the tripping transmission piece is pivoted, so that the circuit breaker is switched to a tripping state.

Description

Thermomagnetic trip for circuit breaker and circuit breaker

Technical Field

The utility model relates to a thermomagnetic release for a circuit breaker and the circuit breaker.

Background

The trip is a common device for releasing a holding mechanism of a circuit breaker so as to automatically open the circuit breaker, and generally can be divided into a magnetic trip, an electronic trip and a thermomagnetic trip, wherein the thermomagnetic trip has very wide application due to the advantages of low cost, stable performance, long service life and the like.

Along with the continuous promotion of policies such as green low carbon, the development and utilization of new energy become the focus of attention, and corresponding business also rapidly develops. Dc circuit breakers are gaining increasing attention. In a short period of years, the technology of the direct current circuit breaker has been developed from the previous 1000V quadrupole strings to 1200V quadrupole strings, 1500V tripolar strings and 1500V diode strings. Products with the same performance have smaller and smaller volumes and lower cost. Commercialization is difficult to achieve without inheritance of technology and reuse of functionality.

Accordingly, there is a need to retrofit an original standard thermal magnetic trip to a thermal magnetic trip for a dc circuit breaker by adding a few parts. Therefore, the investment and the cost of new products are reduced, and the reliable quality and the excellent performance of the original thermomagnetic release are inherited. Of course, the thermomagnetic release can also be used for an alternating current circuit breaker.

Disclosure of Invention

In view of the above-mentioned drawbacks and disadvantages, it is an object of the present utility model to at least solve the above-mentioned problems with the prior art.

The utility model provides a thermomagnetic release for a circuit breaker, the circuit breaker comprising a locking mechanism which can be switched between a locking state in which the circuit breaker is in an on state and an unlocking state in which the circuit breaker is in a tripped state, the thermomagnetic release comprising: an actuation unit comprising actuation means and arranged to be operated such that said actuation means is not operated when the main circuit of the circuit breaker is operating normally or when an overload occurs and said actuation means is operated when the main circuit of the circuit breaker is short circuited; a trip actuating member having a portion actuatable by the actuating member such that movement occurs by movement of the actuating member; a bimetal arranged such that thermally deformable deflection of the bimetal is capable of touching the trip actuating member to cause movement of the trip actuating member; a trip member translatable between a first position in which the trip member is retained against translation by a portion of the trip actuating member, and a second position in which the trip actuating member is disengaged from retaining the trip member upon movement of the trip actuating member, allowing the trip member to translate to the second position; and the tripping transmission piece is abutted with a part of the tripping piece and is configured to pivot along a first direction under the driving of the translation of the tripping piece from the first position to the second position, and is also configured to be abutted with the locking mechanism, and the locking mechanism of the circuit breaker is unlocked when the tripping transmission piece is pivoted, so that the circuit breaker is switched to a tripping state.

Advantageously, the locking mechanism comprises a locking member and a catch, the catch being pivotable between a locking position, in which the locking member abuts the catch to prevent the catch from pivoting in a second direction opposite to the first direction, whereby the catch holds the circuit breaker in an on-state, and a catch, in which the locking member abuts a portion of the trip transmission member, configured to pivot under the drive of the pivoting of the trip transmission member to disengage from the abutment with the catch, allowing the catch to pivot in the second direction, whereby the circuit breaker is switched from the on-state to the off-state, while the operating handle of the circuit breaker is moved from the on-position to an initial position, the on-position corresponding to the on-state of the circuit breaker, the initial position corresponding to the off-state of the circuit breaker.

Advantageously, the thermomagnetic trip unit further comprises a reset member, the handle having a driving surface, the driving surface of the handle being in abutment with the reset member when the handle is moved from the initial position to the trip position in the tripped state of the circuit breaker, thereby causing the reset member to pivot in a first direction, thereby causing a portion of the reset member to abut the trip transmission member, causing the trip transmission member to pivot in a second direction, the pivoting of the trip transmission member in the second direction in turn causing the trip member to translate from the second position to the first position and be held in the first position by the trip actuating member.

Advantageously, the thermal magnetic trip unit further comprises a further trip transmission member translatably arranged between the trip member and the trip transmission member and configured to abut the trip member and the trip transmission member for transmitting forces between the trip member and the trip transmission member.

Advantageously, the actuation unit further comprises an electromagnet unit consisting of a moving armature and a stationary armature, the moving armature being carried and fixed on the actuation member such that the moving armature is deactivated when the main circuit of the circuit breaker is operating normally or when an overload occurs, and such that the actuation member is deactivated when the main circuit of the circuit breaker is short-circuited.

Advantageously, the actuation unit further comprises a current carrying plate assembly, the actuation member being connected to a first portion of the current carrying plate assembly, the static armature being fixed to a second portion of the current carrying plate assembly such that the static armature and the moving armature are opposite each other.

Advantageously, the bimetal is fixed to the current carrying plate assembly.

Advantageously, the actuation member is pivotally connected to the first portion of the current carrying plate assembly.

Advantageously, the trip actuating member has a pivotable body and a first arm connected to the body, wherein the first arm is capable of being pressed by the actuating member and abutting the trip member such that pivoting of the actuating member is capable of pressing the first arm to pivot the first arm out of abutment with the trip member, thereby translating the trip member.

Advantageously, the trip actuating member further comprises a second arm connected to the body, the thermally deformable deflection of the bimetal being capable of pressing against the second arm of the trip actuating member to cause a pivoting movement of the trip actuating member, thereby causing the first arm of the trip actuating member to disengage from abutment with the trip piece, thereby translating the trip piece.

Advantageously, the current carrying plate assembly communicates with a main circuit of the direct current circuit breaker.

The utility model also provides a circuit breaker which comprises the thermomagnetic release.

Drawings

The above and other features and advantages of exemplary embodiments of the present utility model will become more apparent from the following detailed description in conjunction with the accompanying drawings, which are provided for illustrative purposes only and do not limit the scope of the present utility model in any way, wherein:

fig. 1 shows a perspective view of a locking mechanism of a thermo-magnetic release and a circuit breaker according to the present utility model.

Fig. 2 shows a schematic plan view of the thermo-magnetic release and locking mechanism when the circuit breaker is in the closed state.

Fig. 3 shows a schematic plan view of the movement of the actuating member of the actuating unit to pivot the trip actuating member.

Fig. 4 shows a schematic plan view of the movement of the bi-metal strip to pivot the trip actuating member.

Fig. 5 shows a schematic plan view of the trip actuating member driving the trip member to pivot through an angle, while the lock member of the locking mechanism is still abutting the shackle.

Fig. 6 is a schematic plan view showing the trip member pivoting the trip transmission member to disengage the latch from abutment with the catch, with the circuit breaker in the tripped condition.

Fig. 7 shows a schematic plan view of the operating handle in the state of fig. 6, simultaneously moving from the closing position to the initial position.

Fig. 8 shows a schematic plan view of a portion of the trip transmission member moving the operating handle from the initial position to the tripped position.

Fig. 9 shows a schematic plan view of the operation handle moved to the open position, with the trip transmission reset.

Fig. 10 shows a perspective view of the trip transmission.

Fig. 11 shows a schematic view of the abutment of the lock of the locking mechanism of the circuit breaker against the shackle.

Fig. 12 shows a schematic view of the lock out of abutment with the shackle.

Detailed Description

Exemplary embodiments of the present utility model will be described below with reference to the accompanying drawings.

The foregoing and other features, aspects and advantages of the present utility model will become more apparent from the following detailed description of the embodiments, read in conjunction with the accompanying drawings. The directional terms mentioned in the following embodiments are, for example: upper, lower, left, right, front or rear, etc., are merely references to the directions of the drawings. Thus, directional terminology is used for the purpose of illustration and is not intended to be limiting of the utility model, and furthermore, like reference numerals refer to like elements throughout the embodiments.

It is first of all noted that the terms "overload", "overload current" or "overload fault" mentioned above and below denote the situation in which the circuit is overloaded, for example, the situation in which the current is 140% -300% of the rated current; the terms "short circuit", "short circuit current" or "short circuit fault" mean a situation in which a short circuit occurs in the circuit, for example, a situation in which the current is greater than 300% of the rated current. In other words, although in a special sense a short circuit may be regarded as a very special overload situation, in this context both are of different fault types, having different meanings, including a range of currents that do not overlap, an overload current being a relatively small current exceeding the rated current, and a short circuit current being a relatively large current exceeding the rated current, i.e. the short circuit current is not an overload current, also not referred to or regarded as an overload current.

Referring now to fig. 1-12, a thermal magnetic trip in accordance with the present utility model is described.

Reference is first made to fig. 1, which is a perspective view of a latching mechanism of a thermo-magnetic release and circuit breaker according to the present utility model when overload and short circuit faults do not occur. Fig. 2 is a schematic side view of the thermal magnetic trip and locking mechanism in the absence of overload and short circuit faults, in which the housing containing the internal components of the thermal magnetic trip is not shown to better illustrate the internal structure of the thermal magnetic trip.

The thermomagnetic trip for a circuit breaker according to the present utility model includes: an actuating unit comprising an actuating member 20 and arranged to act when the actuating member is not active and the main circuit of the circuit breaker is short-circuited when the main circuit of the circuit breaker is operating normally or when an overload occurs; a trip actuating member 50, the trip actuating member 50 having a portion that can be actuated by the actuating member 20 such that movement occurs by movement of the actuating member 20; a trip piece 70, the trip piece 70 being in abutment with a portion of the trip actuating member 50 and being configured to translate under the actuation of the trip promoting member, the trip piece 70 being translatable between a first position (as shown in fig. 2) in which the trip piece 70 is retained against translation by a portion of the trip actuating member 50 (e.g., a portion of the trip actuating member hooks the trip piece 70 as shown by circle a), and a second position in which the trip actuating member is disengaged from retaining the trip piece in the event of movement of the trip actuating member 50, allowing the trip piece to translate to the right in fig. 2; and a bimetal 60, the bimetal 60 being arranged such that thermally deformed deflection of the bimetal 60 can contact the trip actuating member 50 to cause the trip actuating member to pivot; a trip transmission member 80, the trip transmission member 80 being abutted with a portion of the trip member 70 and configured to be pivotable in a first direction (clockwise direction) under the drive of translation of the trip member 70 from the first position to the second position, the trip transmission member 80 being further configured to be abutted with a locking mechanism 90 (shown in fig. 11 and 12) to unlock the locking mechanism of the circuit breaker upon pivoting, thereby switching the circuit breaker to the tripped state. How the locking mechanism switches the circuit breaker to the tripped state is well known to those skilled in the art and will be described only briefly hereinafter.

Further, referring to fig. 2, the above-mentioned actuating unit includes: current carrying plate assembly 10 (only a portion shown); an actuating member 20, the actuating member 20 being connected to a first portion of the current carrying plate assembly 10; a moving armature 30, the moving armature 30 being carried and fixed on the actuating member 20; a static armature 40, the static armature 40 being secured to the second portion of the current carrying plate assembly 10 such that the static armature 40 and the moving armature 30 oppose each other to collectively form an electromagnet unit configured to operate when the main circuit of the circuit breaker is normally operated or when an overload occurs and when the main circuit of the circuit breaker is shorted. It should be noted that although the actuating unit is described and illustrated herein as a unit actuated by an electromagnet, the present utility model is not limited thereto, but the actuating unit may be of other forms as long as the actuating unit has a member for actuating the trip actuating member and is operated when the main circuit is normally operated or overload occurs and the actuating member is not operated and the main circuit of the circuit breaker is short-circuited.

Meanwhile, it should be noted that although in the drawings, the actuating member 20 and the trip actuating member 50 are shown as pivotable members (described in further detail below), it should be apparent that the present utility model is not limited to the case shown in the drawings, i.e., the actuating member 20 or the trip actuating member 50 may be other movement forms of members, such as members that can translate or translate plus rotate. That is, the present general inventive concept is that when an overload occurs (as shown in fig. 4), the bimetal 60 moves, thereby moving the trip actuating member, thereby actuating the trip member to pivot; and upon occurrence of a short circuit (as shown in fig. 3), the actuating member 20 moves, thereby moving the trip actuating member 50 (which is typically earlier than the bimetal moves the trip actuating member because the magnetic response of the electromagnet unit is faster than the thermal response of the bimetal), thereby actuating the trip pivot. It can be seen that the trip element can be moved, for example, by sliding/translating the moving armature toward the stationary armature, as long as the movement of the actuating member is capable of moving the trip element, regardless of the form of movement of the actuating member.

In addition, it should be noted that although in this description the trip member 70 is shown as a translationally moving component, it should be apparent that the present utility model is not limited to the situation shown in the drawings, i.e., the trip member 70 may be a component of other movement patterns, such as pivoting or translating plus pivoting. That is, the present general inventive concept is that when an overload (shown in fig. 4) or a short circuit (shown in fig. 3) occurs, the trip actuating member moves, thereby releasing the trip member and driving the trip member 70 to move, as long as the trip member can be driven by the trip actuating member regardless of the movement form of the trip member.

Referring now also to fig. 2 to 5, wherein fig. 2 is a schematic side view showing the internal structure of the thermo-magnetic release in the absence of a short circuit or overload fault; FIG. 3 is a schematic side view showing the internal structure of the thermal magnetic release in the event of a short circuit fault; FIG. 4 is a schematic side view showing the internal structure of the thermal magnetic release in the event of an overload fault; FIG. 5 is a schematic side view (reference may be made to FIG. 11 together) showing the disengagement member translated to a second position such that the locking member of the locking mechanism is not completely out of abutment with the shackle; fig. 6 is a schematic side view showing the trip translation driving trip transmission pivoted so that the lock of the locking mechanism is completely out of abutment with the shackle (fig. 12 may be referenced together).

With respect to the design of the actuating member and its associated components, in a preferred embodiment of the present utility model, the actuating member 20 is pivotally connected to a first portion of the current carrying plate assembly 10, the moving armature 30 is attached to the actuating member 20, the static armature 40 is connected to a second portion of the current carrying plate assembly 10, the moving armature 30 and the static armature 40 are opposed to each other to form an electromagnet unit, and the current carrying plate assembly 10 is in communication with the main circuit of the circuit breaker, whereby the electromagnet unit may be energized by the current carrying plate assembly 10. It can be seen that in the preferred embodiment of the present utility model, the current carrying plate assembly serves to both energize and support the electromagnet unit, thereby facilitating structural simplicity. Of course, the electromagnet unit may be energized in other ways as long as the current energized to the electromagnet unit is related to the current of the main circuit of the circuit breaker (e.g., without limitation, there is a proportional relationship between the energized current and the main circuit current) such that the action of the electromagnet unit is related to the current of the main circuit (e.g., overload current and short circuit current).

Further, as shown in fig. 1-3, the actuating member 20 extends upwardly such that the uppermost end of the actuating member 20 is higher than the lowermost end of the trip actuating member 50, such that pivotal movement of the actuating member 20 can actuate the trip actuating member 50. The pivoting movement can realize actuation of corresponding components in a smaller space, thereby being beneficial to miniaturization of the whole thermomagnetic release. Furthermore, actuation of the pivoting movement is also advantageous for improving the operational stability and the service life.

With respect to the design of the trip actuating member and its associated components, in a preferred embodiment of the present utility model, referring to fig. 3, the trip actuating member 50 has a pivotable body and first and second arms 501 and 502 connected to the body, the first arm 501 simultaneously functioning to hold the trip member 70, e.g., hooking the trip member 70, and the pivoting of the actuating member 20 can contact the first arm 501 to pivot the first arm 501, thereby disengaging the first arm 501 from the hold of the trip member 70. As previously mentioned, the structural design of the pivotal movement of the trip actuating member has advantages such as miniaturization, simple structure, reliable operation, and long service life of the thermo-magnetic trip.

With respect to the design of the bi-metallic strip and its associated components, in a preferred embodiment of the present utility model, with reference to fig. 4, bi-metallic strip 60 is attached to the current carrying plate assembly and, when an overload occurs to the circuit, it is heated by the components of the current carrying plate assembly that are attached thereto, thereby deforming and deflecting, thereby depressing second arm 502 of trip actuating member 50 to cause first arm 501 to move out of abutment with trip member 70 in translation.

Therefore, a threshold value can be set for the current of the action of the electromagnet unit, and the threshold value corresponds to the minimum short-circuit current, namely, when the current is smaller than the threshold value, namely, when no short-circuit fault occurs (including normal operation of the circuit and overload fault), the electromagnet unit does not act; and when the current is greater than the threshold value, namely when a short circuit fault occurs, the electromagnet unit acts. More specifically, the electromagnet unit is configured to be energized by the current carrying plate assembly 10 and is configured to not act when the main circuit of the circuit breaker is operating normally or is overloaded, but to act to move the moving armature 30 toward the static armature 40 when the main circuit of the circuit breaker is shorted, such that the actuating member 20 rotates to contact the trip actuating member 50 to cause translational movement of the trip unit 70.

On the other hand, the bimetal 60 is configured to be heated by the current carrying plate assembly 10, and is configured such that the thermally deformable deflection of the bimetal 60 is insufficient to contact the trip actuating member 50 to cause movement of the trip actuating member 50 when the main circuit of the circuit breaker is operating normally, and the thermally deformable deflection of the bimetal 60 contacts the trip actuating member 50 to cause translational movement of the trip member 70 when the main circuit of the circuit breaker is overloaded.

In addition to trip transmission member 80, the thermal magnetic trip unit may include another trip transmission member 200 translatably disposed between trip unit 70 and trip transmission member 80 for transmitting force between trip unit 70 and trip transmission member 80. It should be appreciated that the other trip transmission member 200 is not required and that the other trip transmission member 200 may be omitted if the trip member 70 is sufficiently long.

Specifically, during tripping, the other trip transmission member 200 is translated by abutment of the trip member 70 and further abuts the trip transmission member 80 to rotate it; during reset, the other trip transmission member 200 is translated by abutment of the trip transmission member 80 and further translates against the trip member 70.

The process of the circuit breaker from the closed state to the tripped state will be described below by taking a short-circuit fault as an example, and a process when an overload fault occurs will be easily understood by those skilled in the art.

Fig. 2 shows the circuit breaker in a closed state, when a short circuit fault occurs, the moving armature 30 rotates toward the stationary armature 40, so that the actuating member 20 rotates together with the moving armature 30 under the driving of the moving armature 30. As shown in fig. 3, the actuating member 20 abuts the first arm 501 of the trip actuating member 501, thereby pivoting the trip actuating member 501 in a counterclockwise direction in the drawing (i.e., a second direction opposite the first direction), which causes the first arm 501 of the trip actuating member 501 to disengage from the retention of the trip member 70, such that the trip member 70 translates rightward in the drawing under the influence of its own spring (not shown). Translation of the trip member 70 in turn causes translation of the other trip transmission member 200, translation of the other trip transmission member 200 causes pivoting of the trip transmission member 80, as shown in fig. 5, at which time the lock 901 of the locking mechanism 90 remains against the catch 902, as shown in fig. 11, maintaining the circuit breaker in the closed state without trip. As the trip transmission member 80 continues to pivot, the latch 901 pivots counterclockwise in the figure, as shown in fig. 6, thereby disengaging the abutment against the catch 902, which causes the catch 902 to also pivot counterclockwise, thereby tripping the breaking unit of the circuit breaker. It is well known to those skilled in the art how the pivoting of the catch 902 causes the breaking unit of the circuit breaker to trip, and will not be described in detail herein.

In addition, in the state switching from fig. 6 to fig. 7, in addition to the trip of the circuit breaker, the operating handle 100 of the circuit breaker is also switched from the closing position to the initial position, which is also well known to those skilled in the art. The switching of the operating handle from the closing position to the starting position is only briefly described here, the specific structure of which is known to the person skilled in the art and is not relevant to the focus of the utility model and will not be described in detail here.

After tripping, the moving armature is reset away from the stationary armature, which resets the actuating member as well, thereby resetting the trip actuating member. To reset the thermal magnetic release, as shown in fig. 8, the operating handle 100 is rotated in a counterclockwise direction in the drawing from the initial position to the release position, which causes a portion of the driving portion 101 of the operating handle 100 to abut the reset member 300, causing the reset member 300 to pivot in a first direction, and thus a portion of the reset member 300 to abut the trip transmission member 80 to pivot in a second direction, causing the other trip transmission member 200 to translate leftward, and thus the trip member 70 to translate leftward to the first position. Finally, the trip member 70 is again held by abutment of the first arm 501 of the trip actuating member, as shown in fig. 9.

Fig. 10 shows a perspective view of the trip transmission member 80. The trip transmission member 80 has a first surface 801 for abutting and being driven by the trip member 70 to pivot the trip transmission member during tripping and a second surface 802 for abutting and being driven by a portion of the operating handle to pivot the trip transmission member during resetting.

In a preferred embodiment of the present utility model, there is also provided a circuit breaker including: according to the thermomagnetic release as described above.

According to the circuit breaker disclosed by the utility model, the original standard thermomagnetic release is transformed into the thermomagnetic release for the direct-current circuit breaker by only adding the release transmission piece. Therefore, the investment and the cost of new products are reduced, and the reliable quality and the excellent performance of the original thermomagnetic release are inherited.

Although the utility model has been described in the specification and illustrated in the accompanying drawings on the basis of various embodiments, it will be understood by those skilled in the art that the above embodiments are merely preferred implementations, and that certain technical features in the embodiments may not be necessary to solve a particular technical problem so that these technical features may be omitted or omitted without affecting the solution of the technical problem or the formation of the technical solution; furthermore, the features, elements, and/or functions of one embodiment may be combined, or otherwise matched as appropriate with the features, elements, and/or functions of other one or more embodiments, unless such combination, or match is clearly impractical.

Claims (12)

1. A thermo-magnetic release for a circuit breaker, the circuit breaker comprising a locking mechanism, the locking mechanism being switchable between a locked state in which the circuit breaker is in an on state and an unlocked state in which the circuit breaker is in a tripped state, the thermo-magnetic release comprising:

an actuation unit comprising actuation means and arranged to be operated such that said actuation means is not operated when the main circuit of the circuit breaker is operating normally or when an overload occurs and said actuation means is operated when the main circuit of the circuit breaker is short circuited;

a trip actuating member having a portion actuatable by the actuating member such that movement occurs by movement of the actuating member;

a bimetal arranged such that thermally deformable deflection of the bimetal is capable of touching the trip actuating member to cause movement of the trip actuating member;

a trip member translatable between a first position in which the trip member is retained against translation by a portion of the trip actuating member, and a second position in which the trip actuating member is disengaged from retaining the trip member upon movement of the trip actuating member, the trip member translating to the second position;

and the tripping transmission piece is abutted with one part of the tripping piece and the locking mechanism, and is configured to be pivoted along a first direction under the driving of the pivoting of the tripping piece from the first position to the second position, so that the locking mechanism of the circuit breaker is unlocked, and the circuit breaker is switched to a tripping state.

2. The thermal-magnetic trip unit of claim 1, wherein the locking mechanism includes a lock member and a catch, the catch being pivotable between a locked position in which the lock member abuts the catch to prevent the catch from pivoting in a second direction opposite the first direction, such that the catch holds the circuit breaker in the on state, and a catch abutting a portion of the trip transmission member, the catch being configured to pivot under the urging of the pivot of the trip transmission member to disengage from the catch, allowing the catch to pivot in the second direction, thereby switching the circuit breaker from the on state to the trip state, while the operating handle of the circuit breaker moves from the on position to the initial position, the on position corresponding to the on state of the circuit breaker, the trip position corresponding to the trip state of the circuit breaker.

3. The thermal magnetic trip unit of claim 2, wherein the thermal magnetic trip unit further comprises a reset member, the handle having a drive surface, the drive surface of the handle abutting the reset member when the handle is moved from the initial position to the tripped position in the tripped state of the circuit breaker, thereby pivoting the reset member in a first direction, thereby causing a portion of the reset member to abut the trip transfer member, causing the trip transfer member to pivot in a second direction, the pivoting of the trip transfer member in the second direction in turn causing the trip member to translate from the second position to the first position and be retained in the first position by the trip actuating member.

4. A thermal magnetic trip unit according to any one of claims 1 to 3 further comprising a further trip transmission member translatably disposed between the trip member and the trip transmission member and configured to be capable of abutment with the trip member and the trip transmission member to thereby transmit force therebetween.

5. The thermal-magnetic trip unit according to claim 2, wherein said actuating unit further comprises an electromagnet unit consisting of a moving armature and a static armature, said moving armature being carried and fixed on said actuating member such that said moving armature is deactivated and said actuating member is deactivated when the main circuit of the circuit breaker is operating normally or when an overload occurs, and said moving armature is activated and said actuating member is activated when the main circuit of the circuit breaker is shorted.

6. The thermal-magnetic release of claim 2, wherein the actuation unit further comprises a current-carrying plate assembly, the actuation member being coupled to a first portion of the current-carrying plate assembly, the stationary armature being secured to a second portion of the current-carrying plate assembly such that the stationary armature and the movable armature oppose each other.

7. The thermomagnetic trip unit according to claim 6, wherein the bi-metallic strip is secured to the current carrying plate assembly.

8. The thermal magnetic release of claim 7, wherein the actuating member is pivotally connected to the first portion of the current carrying plate assembly.

9. The thermal magnetic trip unit of any one of claims 1-3, wherein the trip actuating member has a pivotable body and a first arm connected to the body, wherein the first arm is capable of being depressed by the actuating member and is in abutment with the trip member such that pivoting of the actuating member is capable of depressing the first arm to pivot the first arm out of abutment with the trip member and thereby translate the trip member.

10. The thermomagnetic trip unit according to claim 9, wherein the trip actuating member further comprises a second arm connected to the body, the thermally deformable deflection of the bimetal being capable of contacting the second arm of the trip actuating member to cause pivotal movement of the trip actuating member to disengage the first arm of the trip actuating member from abutment with the trip member to translate the trip member.

11. The thermomagnetic trip unit according to claim 6, wherein the current carrying plate assembly is in communication with a main circuit of a dc circuit breaker.

12. A circuit breaker, characterized in that it comprises a thermomagnetic trip as claimed in any one of claims 1 to 11.