DESC:TRIP ENABLER-AMPLIFIER FOR MECHANISM OF CIRCUIT BREAKER

Field of the invention:

The present invention generally relates to a trip mechanism for a circuit breaker and more particularly to a trip enabler-amplifier for a mechanism of a moulded case circuit breaker with a thermal-magnetic release for sensing and tripping.

Background of the invention:

A circuit breaker is a mechanical switching device capable of making, carrying and breaking currents. Under normal circuit conditions, the circuit breaker will make the circuit closed, carry current for a specified time and breaks the circuit under specified abnormal circuit conditions.

Moulded case circuit breakers (MCCB) is employed for current interruption and more particularly, for protecting equipments in downstream from damage during adverse conditions prevailing during the operation of the circuit in which the MCCB is employed. During adverse conditions like short circuit, the current rises to an alarmingly high level. This high current may cause damage to the parts/equipments in the electrical system. Hence, during these conditions the circuit has to be opened to protect the parts/equipments connected after the breaker.

The circuit breaker can be manually opened and closed, as well as automatically opened to protect conductors or equipments from damage caused by excessive heating due to over current in abnormal conditions such as overload or short-circuit by an operating mechanism that plays a vital role in determining the credibility of the circuit breaker. A good operating mechanism should ensure quick and manually independent opening and closing of a contact system of the circuit breaker. The operating mechanism performs five operations such as ‘ON’, ‘OFF’, ‘TRIP’, ‘TRIP FREE’ and ‘RESET’. The first two operations are initiated by an operator. The operator has access to the operating mechanism through a knob that will be projected outwards from a housing of the breaker. The knob is placed over a fork of the operating mechanism. In conventional type MCCBs, the circuit breaker featured three positions in a top cover near the knob to show ON, OFF and TRIP. The trip signal is given by a thermal-magnetic release mechanism that senses the abnormal conditions and gives TRIP command to the operating mechanism, so that the latter opens the circuit. Since, the TRIP command from thermal parts of the thermal-magnetic release mechanism is less in magnitude, there is a need of amplification of the rotation to enable the TRIP.

The thermal-magnetic release helps in protecting the parts/equipments connected in the circuit breaker during adverse conditions by disconnecting the supply downstream. For disconnecting the supply, the thermal-magnetic release depends on the operating mechanism of the breaker; in particular, it depends on the TRIP and TRIP FREE operations of the circuit breaker. The TRIP is the requirement of the tri-state circuit breaker for isolating the circuit breaker from the circuit. And will not become a part of the circuit unless the circuit breaker RESETs. TRIP FREE is a required feature particularly in case of motor operated / interlocked breakers, as the knob will be held at ON condition and cannot come back to TRIP position on its own.

The operating mechanism suffers several drawbacks due to requirement of a minimum of three components including TMR tripper, spring (for providing trip force) and lock for TMR tripper (for holding it ready to TRIP) for tripping when there is a fault occurrence, requirement of at least one more component such as TMR tripper-resetter to reset the release for further operation, requirement of minimum two components including thermal tuning slider and thermal tuning rotary knob in the circuit breaker to make the thermal release as variable.

Accordingly, there is a need of a trip enabler-amplifier for a mechanism of a circuit breaker equipped with a thermal-magnetic release that overcomes the above mentioned drawbacks of the prior art.

Object of the invention:

An object of the present invention is to enable TRIP command to reach an operating mechanism and to amplify the available rotary movement to a desired level with usage of minimum components.

Summary of the invention:

Accordingly, the present invention provides a trip enabler-amplifier for a mechanism of a circuit breaker. The circuit breaker is a molded case circuit breaker. The circuit breaker includes a contact system and a thermal-magnetic release that are operably connected with the mechanism. The contact system includes a drive shaft and a pair of drive shaft pins. The mechanism includes a pair of mounting plates, a latch link, a pair of upper links, a pair of lower links, a fork, a latch bracket, a pair of latch bracket pins, a spacer, a trip plate, a trip biasing spring, a reset pin, a spring pin and a pair of main springs that are operably connected with each other. The pair of the mounting plates includes a pair holding profiles (MP1) configured thereon. The trip plate is configured with a pair of flat mirrored profiles (TP1) and a flat profile (TP2) thereon.

The trip enabler-amplifier comprises a pair of receiving profile (T1), a plurality of protruding inclined profiles (T2), a pair of flat mirrored profiles (T3), a flat profile (T4) and a sliding profile (T5) configured thereon. The pair of receiving profile (T1) the trip enabler-amplifier is mounted on the pair holding profiles (MP1) of the pair of the mounting plates. The plurality of protruding inclined profile (T2) is configured to receive a trip command from interacting parts of the thermal-magnetic release. The pair of flat mirrored profiles (T3) is configured to rotate in a clock-wise direction upon receiving the trip command. The pair of flat mirrored profiles (T3) interacts with a pair of flat mirrored profiles (TP1) of the trip plate for rotating the trip plate in an anti-clockwise direction and completes a first stage of a tripping operation. The flat profile (T4) is configured to interact with the flat profile (TP2) of the trip plate for completely rotating the trip plate in an anti-clockwise direction thereby completing the tripping operation and delatching of the latch bracket. The sliding profile (T5) is capable of being slided to vary a distance between the plurality of a protruding inclined profile (T2) and the interacting parts of the thermal-magnetic release enabling variation in a thermal setting thereof. The trip enabler-amplifier enables the trip command from the thermal-magnetic release and amplifies magnitude of rotation produced by the thermal-magnetic release by two times to perform the tripping operation.

Brief description of the drawings:

Other features as well as the advantages of the invention will be clear from the following description. In the appended drawings:

Figures 1 and 2 show isometric views of a circuit breaker, in accordance with the present invention;

Figure 3 shows an isometric view of a thermal magnetic release, in accordance with the present invention;

Figures 4 and 5 show isometric views of a mechanism of the circuit breaker, in accordance with the present invention;

Figure 6 shows an exploded view of the mechanism of the circuit breaker, in accordance with the present invention;

Figure 7 shows a mounting plate, in accordance with the present invention;
Figures 8 and 9 show a trip enabler-amplifier, in accordance with the present invention;

Figure 10 shows a trip plate, in accordance with the present invention;

Figure 11 shows an assembly procedure of the trip enabler-amplifier, in accordance with the present invention;

Figure 12 shows a top view of the circuit breaker showing the adjustment for variable thermal settings, in accordance with the present invention;

Figure 13 shows a front view of the circuit breaker at ON position, in accordance with the present invention;

Figure 14 shows a cross-sectional view of the circuit breaker at ON position, in accordance with the present invention;

Figure 15 shows a front view of tripping parts in ON/OFF position, in accordance with the present invention;

Figure 16 shows a cross-sectional view of the tripping parts in ON/OFF position, in accordance with the present invention;

Figure 17 is a cross-sectional view showing a first stage of tripping, in accordance with the present invention;

Figure 18 shows a rear view of the mechanism showing a pair of flat mirrored profiles of the trip plate and a pair of flat mirrored profiles of the trip enabler-amplifier, in accordance with the present invention;

Figure 19 shows an isometric view of the mechanism showing the pair of flat mirrored profiles of the trip plate and the pair of flat mirrored profiles of the trip enabler-amplifier, in accordance with the present invention.

Figure 20 shows an end of the first stage and initiation of a second stage of tripping, in accordance with the present invention;

Figure 21 shows the amplification principle used for the trip enabler-amplifier, in accordance with the present invention;

Figure 22 show a cross-sectional view illustrating end of the second stage of tripping, in accordance with the present invention;

Figure 23 shows a front view of the circuit breaker at TRIP position, in accordance with the present invention;

Figure 24 shows a cross-sectional view of the circuit breaker at TRIP position, in accordance with the present invention; and

Figure 25 shows a cross-sectional view illustrating resetting direction of the trip plate and the trip enabler / amplifier, in accordance with the present invention.

Detailed description of the embodiments:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides a trip enabler- amplifier for a mechanism of a circuit breaker equipped with thermal - magnetic release. The trip enabler-amplifier enables the TRIP command from the thermal - magnetic release to reach an operating mechanism and amplifies the available rotary movement of the trip enabler- amplifier produced by the linear movement of thermal parts of the thermal - magnetic release to a desired level with usage of minimum components.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.

Referring to figures 1-25, a trip enabler- amplifier (20) for a mechanism (50) of a circuit breaker (100) in accordance with the present invention is shown. Specifically, the circuit breaker (100) is a moulded case circuit breaker (MCCB). The MCCB has a modular construction to help the customer/manufacturer to replace only the module(s) damaged during the occurrence of fault. The circuit breaker (100) includes a contact system (30), a mechanism (50) (refer figures 4-6) and a thermal-magnetic release (herein after ‘the release’) (60) (refer figure 3).

The contact system comprises a drive shaft (21), a pair of drive shaft pins (22) (herein after ‘the drive shaft pins (22)’) and few other components which are well known in the art, so are not discussed in detail herein.

The mechanism (50) comprises a pair of mounting plates (1) (herein after ‘the mounting plates (1)’), a latch link (2), a pair of upper links (3) (herein after ‘the upper links (3)’), a pair of upper link rivets (4), a pair of lower links (5) (herein after ‘the lower links (5)’), a fork (6), a latch bracket (7), a pair of latch bracket pins (8), a fork spring pin (9), a latch link pin (10), a pair of fork rivets (11), a spacer (12), a trip plate pin (13), a trip plate (14), a trip biasing spring (15), a reset pin (16), a spring pin (17), a pair of main springs (18) (herein after ‘the main springs (18)’), a knob (19) and the trip enabler-amplifier (20).

The mounting plates (1) include a pair holding profiles (MP1) (refer figure 7) configured thereon. The fork (6) is mounted on the mounting plates (1) with the help of the pair of fork rivets (11). The knob (19) is mounted on the fork (6). The knob (19) operates the fork (6) for mobilizing the circuit breaker (100) to a desired position selected from any one of ON, OFF and TRIP positions.

The upper links (3) and the main springs (18) are placed in their respective positions in the spring pin (17) and the assembly thereof is connected to each side of the latch link (2) with the help of the pair of upper link rivets (4) to form a latch link assembly (not numbered). The latch link assembly is hinged to the mounting plates (1) with the help of the latch link pin (10). The latch link assembly is responsible for the operation of the circuit breaker (100). The lower links (5) are attached to each side of the latch link assembly in the spring pin (17) and are used for transmitting the power from the mechanism (50) to the drive shaft (21) through the drive shaft pins (22) of the circuit breaker (100).

The latch bracket (7) is hinged to the mounting plates (1) with the help of the pair of latch bracket pins (8). The latch bracket (7) is responsible for holding the latch link assembly in latched condition that is a pre-requisite for the mechanism (50) to be switched ON/OFF.

The trip plate (14) is hinged along with the trip biasing spring (15) to the mounting plates (1) with the help of the trip plate pin (13) and is responsible for holding the latch bracket (7) in latched condition and to trip the mechanism (50) by allowing the latch bracket (7) to delatch. The trip plate (14) is configured with a pair of flat mirrored profiles (TP1) and a flat profile (TP2) thereon (refer figure10).

The rollable reset pin (16) is assembled with the latch link (2) to reset the mechanism (50) back to the OFF position as partially indicated in the figure 25 and to stop the fork (6) in the TRIP position as indicated in the figure 23. The main springs (18) is mounted to the spring pin (17) and the fork (6) with the help of a fork spring pin (9) to provide the force required to operate the circuit breaker (100).

The trip enabler-amplifier (20) comprises a pair of receiving profile (T1), a plurality of protruding inclined profiles (T2), a pair of flat mirrored profiles (T3), a flat profile (T4) and a sliding profile (T5) configured thereon (refer figures 8 and 9). The trip enabler-amplifier (20) is assembled on the mounting plates (1) as depicted in figure 11. The pair of receiving profile (T1) of the trip enabler-amplifier (20) is inserted into the pair holding profiles (MP1) of the mounting plates (1) at certain angle in a way that the plurality of protruding inclined profiles (T2) faces the bottom. Thereinafter, the trip enabler-amplifier (20) is rotated in clockwise direction as shown in figure 11 to achieve final assembled position thereof. In an embodiment, the final assembled position represents the position of TRIP of the trip enabler-amplifier (20).

The trip enabler-amplifier (20) enables the TRIP operation by executing the TRIP command from interacting parts (not numbered) of the release (60) and amplifies the rotation available from the parts of the release (60). In an embodiment, the interacting parts include screws attached to a bimetal strip in case of the thermal release and an I-core in case of the magnetic release. The plurality of protruding inclined profiles (T2) is adapted to receive a trip command from the release (60).

Upon receiving the trip command, the trip enabler-amplifier (20) starts rotating in a clockwise direction such that the pair of flat mirrored profiles (T3) of the trip enabler-amplifier (20) interacts with the pair of flat mirrored profiles (TP1) of the trip plate (14) thus rotating the trip plate (14) in an anti-clockwise direction as shown in the figures 15 to 17, thereby completing a first stage of a tripping operation.

Once the stage 1 tripping is complete, the pair of flat mirrored profiles (T3) of the trip enabler-amplifier (20) stops interacting with the pair of flat mirrored profiles (TP1) of the trip plate (14) and the flat profile (T4) of the trip enabler-amplifier (20) starts interacting with the flat profile (TP2) of the trip plate (14) as shown in the figures 18 to 20. The tripping or delatching operation completes as the flat profile (T4) of the trip enabler-amplifier (20) rotates the trip plate (14) completely to a desired rotation with the help of the flat profile (TP2) of the trip plate (14) as shown in the figure 22. Specifically, the desired rotation is the rotation required to delatch the latch bracket (7). The trip enabler-amplifier (20) amplifies the magnitude of rotation obtained from the release (60) by two times to perform the tripping operation as depicted in the figure 21.

For adjusting the thermal settings of the release (60), the trip enabler-amplifier (20) is slided. Specifically, the sliding profile (T5) of the trip enabler-amplifier (20) is slided such that the distance between the plurality of protruding inclined profiles (T2) of the trip enabler-amplifier (20) and the interacting parts of the release varies (both increases or decreases as required) enabling a thermal setting variation of the release (60) as shown in the figure 12. The mechanism (50) further includes an adjuster (not shown) configured thereon for converting the circuit breaker (100) into a breaker with variable thermal release.

The circuit breaker (100) is resetted by moving the knob (19) towards the OFF position from the TRIP position. This movement loads the main spring (18) and latches the latch link (2) to the latch bracket (7). As the latch bracket (7) holds the latch link (2), the trip plate (14) resets the position by rotating in anti-clockwise direction as shown in the figure 25 with the help of the trip biasing spring (15). Also, the trip enabler-amplifier (20) is reset by lifting the flat profile (T4) and the pair of flat mirrored profiles (T3) of the trip enabler-amplifier (20) with the help of the flat profile (TP2) and the pair of flat mirrored profiles (TP1) of the trip plate (14) and the reset position is shown in the figure 15.

Advantages of the invention:

1. Unlike other products, which require more components such as TMR tripper, spring (for providing trip force) and lock for TMR tripper (for holding it ready to TRIP) for achieving this requirement, this concept requires only one component, the trip enabler-amplifier (20), connected to the conventional mechanism assembly that can efficiently trip the mechanism (50) when there is a fault occurrence.
2. And unlike other breakers which have a plastic component riveted/attached directly to the trip plate with fixed thermal settings, the trip enabler-amplifier (20) is a standalone/separate plastic component interacting with the mechanism (50) after the input come from release unit. The trip enabler-amplifier (20) is capable of being adjusted for desired range of thermal settings of the release (60) with the inclusion of another component (an adjusting knob) thus converting a fixed thermal trip unit/ fixed thermal fixed magnetic type of release to a variable thermal trip unit/ variable thermal fixed magnetic type of release. Thus, one component is enough in the circuit breaker to make the thermal release as variable.
3. The trip plate (14) is capable of resetting the trip enabler-amplifier (20) making it suitable for further operation eliminating the requirement of minimum one component (retaining spring).
4. The trip enabler-amplifier (20) trips the mechanism to complete the tripping operation in two stages. In the first stage, the TRIP command is initiated by the Trip Enabler-Amplifier (20) and in the second stage; the TRIP command is amplified and completed.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.
,CLAIMS:We Claim:

1. A trip enabler-amplifier (20) for a mechanism (50) of a circuit breaker (100), the circuit breaker (100) being a molded case circuit breaker, the circuit breaker (100) having a contact system having a drive shaft (21) and a pair of drive shaft pins (22) and a thermal-magnetic release (60) being operably connected with the mechanism (50), the mechanism (50) having a pair of mounting plates (1), a latch link (2), a pair of upper links (3), a pair of upper link rivets (4), a pair of lower links (5), a fork (6), a latch bracket (7), a pair of latch bracket pins (8), a pair of fork rivets (11), a spacer (12), a trip plate pin (13), a trip plate (14), a trip biasing spring (15), a reset pin (16), a spring pin (17), a pair of main springs (18) and a knob (19) being operably connected with each other, the trip enabler-amplifier (20) comprising:
• a pair of receiving profile (T1) being configured for mounting in a pair holding profiles (MP1) of the pair of mounting plates (1);
• a plurality of protruding inclined profile (T2) being configured to receive a trip command from interacting parts of the thermal-magnetic release;
• a pair of flat mirrored profiles (T3) being configured to rotate in a clock-wise direction upon receiving the trip command and to interact with a pair of flat mirrored profiles (TP1) of the trip plate (14) for rotating the trip plate (14) in an anti-clockwise direction thereby completing a first stage of a tripping operation;
• a flat profile (T4) being configured to interact with a flat profile (TP2) of the trip plate (14) for completely rotating the trip plate (14) in an anti-clockwise direction thereby completing the tripping operation and delatching of the latch bracket (7); and
• a sliding profile (T5) capable of being slided to vary a distance between the plurality of a protruding inclined profile (T2) and the interacting parts of the thermal-magnetic release enabling variation in a thermal setting thereof;
wherein, the trip enabler-amplifier (20) executes the trip command in two stages and amplifies magnitude of rotation produced by the thermal-magnetic release by two times, thus amplifying the trip force almost twice to trip the circuit breaker (100).

2. The trip enabler-amplifier (20) as claimed in claim 1, wherein the trip enabler-amplifier (20) is assembled by inserting the pair of receiving profile (T1) into the pair holding profiles (MP1) of the mounting plates (1) at an angle with the plurality of protruding inclined profiles (T2) facing towards bottom, thereby rotating the trip enabler-amplifier (20) in clockwise direction to achieve final assembled position representing TRIP position thereof.

3. The trip enabler-amplifier (20) as claimed in claim 1, wherein the interacting parts includes screws attached to a bimetal strip in case of the thermal release and an I-core in case of the magnetic release.

4. The trip enabler-amplifier (20) as claimed in claim 1, wherein the trip biasing spring (15) resets the the trip plate (14) and the trip enabler-amplifier (20), the trip biasing spring (15) rotates the trip plate (14) in anti-clockwise direction to lift the flat profile (TP2) and the pair of flat mirrored profiles (TP1) thereof thereby resetting the trip plate (14) and thus lifting the flat profile (T4) and the pair of flat mirrored profiles (T3) of the trip enabler-amplifier (20) to reset the position thereof.

5. The trip enabler-amplifier (20) as claimed in claim 1, wherein an adjuster is configured for converting the circuit breaker (100) into a breaker with variable thermal release.

Dated this 19th day of August 2016
Prafulla Wange
(Agent for Applicant)
IN-PA/2058