Protective device and circuit of electrical engineering distribution transformer

Abstract

The invention discloses a protection device and circuit for an electrical engineering distribution transformer, the protection device comprises a protection seat and a buckle part, the protection seat is provided with a conductive strip installation structure in an open circuit state, and the buckle part is provided with a power supply and a protection mechanism; after the buckling part is buckled with the protection seat, a circuit of the disconnected bus bar mounting structure can be conducted, and the conducted circuit passes through the protection mechanism; the protection mechanism comprises a conductive rod telescopic assembly and a fusing assembly. The conductive rod telescopic assembly can be in contact with one of the conductive strips after extending into the protective seat; the fusing assembly abuts against and is electrically connected with the conductive rod telescopic assembly so that the conductive rod assembly can stretch into the protection base. The fusing assembly is provided with an over-current fusing and length reducing structure. And a sound-light alarm device is arranged in the protective seat. A two-stage protection structure is adopted to protect the transformer, on one hand, the protection device is installed in the distribution box, and the fuse can be fused after overcurrent of the protection device, so that an access is disconnected; and secondly, a protection circuit is arranged in the distribution box to serve as secondary protection.

Description

Technical Field

[0001] The invention relates to a transformer, in particular to a protection device and a circuit for a distribution transformer in an electrical engineering. Background Art

[0002] Transformer is a device that uses the principle of electromagnetic induction to change AC voltage. Its main components are primary coil, secondary coil and iron core. According to its use, it can be divided into: distribution transformer, combined transformer, dry transformer and oil-immersed transformer, etc. Transformer is one of the most critical equipment in national economic life, especially oil-immersed transformer. Because it carries a wide range of power transmission and transformation tasks, its safety and normal operation are particularly important.

[0003] In the prior art, when a transformer encounters an insulation fault that causes an increase in its internal pressure, a pressure relief valve is usually used to release the pressure. Practice has proven that the pressure relief valve can play a role in the normal pressure rise and fall of the transformer. When an intense arc such as an insulation fault occurs, the internal pressure of the transformer rises very quickly. At this time, due to the inherent mechanical characteristics of the pressure relief valve itself, the pressure cannot be released in time, resulting in the explosion of the transformer. Analysis of the transformers that have exploded shows that these transformers are all equipped with the above-mentioned pressure relief valve, but they still failed to prevent the explosion. This shows that installing a pressure relief valve cannot prevent the explosion of the transformer.

[0004] In view of this, it is necessary to install a protective device on the power supply control box of the distribution transformer to solve the above technical problems. Summary of the invention

[0005] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a protection device and circuit for an electrical engineering distribution transformer. The purpose of designing the protection device is to prevent damage to the transformer caused by excessive current.

[0006] To solve the above technical problems, the present invention is implemented by the following scheme: A protective device for an electrical engineering distribution transformer of the present invention comprises a detachably connected protective seat and a buckle, wherein the protective seat has a conductive strip mounting structure in an off-circuit state, and the buckle has a power supply and a protective mechanism; After the buckle part is buckled with the protection seat, the circuit of the disconnected conductive strip installation structure can be turned on, and the turned-on circuit passes through the protection mechanism; The protection agencies include: A conductive rod telescopic assembly that is telescopic and can be extended into the protective seat, and the conductive rod telescopic assembly can contact one of the conductive strips in the protective seat after being extended into the protective seat; A fuse assembly, which is pressed against and electrically connected to the conductive rod telescopic assembly so that the conductive rod assembly extends into the protective seat, and the fuse assembly has an overcurrent fusing and length shortening structure; The protection seat is provided with an audible and visual alarm device; The buckle portion also has an on-off mechanism capable of conducting the sound and light alarm device, and the on-off mechanism includes: A passive switch is arranged on the buckle part. After the buckle part is inserted into the protective seat, the passive switch is in electrical contact with the sound and light alarm device and can control the on and off of the sound and light alarm device. The passive switch is electrically connected to the power supply. A pressure head is fixed on the conductive rod telescopic assembly. When the pressure head is pressed down, the passive switch can be disconnected, and when the pressure head is raised, the passive switch is automatically turned on.

[0007] Further, the protection seat is a U-shaped structural member, having a U-shaped cavity inside, and the bottom surface of the U-shaped opening of the protection seat is provided with four through holes, which are respectively a first through hole, a second through hole, a third through hole and a fourth through hole; The conductive bar installation structure in the disconnected state includes: A left conductive strip, one end of which is fixed to the left cavity of the U-shaped cavity, and the other end of which extends to just below the first through hole; The right conductive strip has one end fixed to the right cavity of the U-shaped cavity and the other end extending to just below the second through hole.

[0008] Furthermore, the buckle portion includes: A buckle shell, comprising a battery slot, a straight cavity and an end hole, wherein a first end of the straight cavity faces the second through hole, and a second end thereof is connected to an end hole, and a side opening is provided on a side of the straight cavity, and the power source is a rechargeable battery, which is installed in the battery slot; A first elastic electrode, disposed in the side opening, the round end of the first elastic electrode being retractable and located in the straight cavity area; The first terminal is protruding and fixed on the plug end of the buckle shell, and is electrically connected to the first elastic electrode. After the buckle part is buckled on the protective seat, the first terminal passes through the first through hole and contacts with the left conductive strip.

[0009] Furthermore, the conductive rod telescopic assembly comprises a conductive rod and a first compression spring, wherein the thick section of the conductive rod is in the straight cavity, and the thin section thereof extends to the second through hole, and the first compression spring is sleeved on the thin section, with one end thereof abutting against the inner edge of the second through hole, and the other end thereof abutting against the step between the thick section and the thin section; After the conductive rod is pressed against the fuse assembly, its lower end contacts the right conductive bar; The pressure head is an insulating pressure head, and one side of the insulating pressure head is fixed to the conductive rod.

[0010] Furthermore, a blocking plate for limiting the upward distance of the pressure head is provided on one side of the straight cavity.

[0011] Furthermore, the fuse assembly includes: A lower pole, one end of which is a flat end, the flat end forms a contact-type electrical connection with the conductive rod, the other end of which is provided with an annular retaining ring, the bottom surface of which is provided with first jacks distributed in a ring array; An upper pole, wherein the first surface of the upper pole facing the lower pole is provided with second jacks distributed in a ring array, and after the fuse assembly is positioned, the first elastic electrode contacts the upper pole; A plurality of fuses, wherein the first end pin of the fuse is inserted into the first jack, and the second end pin of the fuse is inserted into the second jack; The insulating member is fixed to the second surface of the upper pole.

[0012] Furthermore, an insulating cover is screwed onto the end hole.

[0013] Furthermore, the fuse also includes a resistance wire assembly; The resistance wire assembly includes: A glass rod, both ends of which are connected to the first end pin and the second end pin respectively, and has a cavity inside; A resistance wire, which is arranged in the cavity, and whose two ends are respectively connected to the first end pin and the second end pin; The easily expandable liquid is filled in the cavity.

[0014] Furthermore, the sound and light alarm device is fixed to the bottom cavity of the U-shaped cavity, and two power supply terminals are provided on the top of the shell, and the two power supply terminals are respectively opposite to the third through hole and the fourth through hole; The passive switch comprises: An insulating bracket, fixed in the buckle portion, provided with a contact terminal connected to the positive electrode of the power source and a spring column cavity; Two electrical pins fixed to the insulating bracket, the two electrical pins can enter the third through hole and the fourth through hole respectively, and contact the two power supply terminals one by one, and a first electrical pin is electrically connected to the negative electrode of the power supply; A second elastic electrode, fixed in the insulating bracket, with a non-retractable end electrically connected to the second electrical pin and a retractable end facing the contact terminal; A second compression spring, disposed in the spring column cavity; A hard terminal, wherein a first end of the hard terminal is fixedly connected to the upper end of the second compression spring, and a second end of the hard terminal extends to the upper end of the telescopic end and is located below the contact terminal; The pressing key is fixed to the first end of the hard terminal, and the outer end of the pressing key extends out of the insulating bracket and faces the pressing head.

[0015] A circuit of the present invention is applied to the electrical engineering distribution transformer, and includes an audible and visual alarm circuit and a secondary protection circuit; The sound and light alarm circuit comprises: Speaker BZ1, positive pole connected to hard terminal; A transistor Q24, the collector of which is connected to the cathode of the speaker BZ1, and the emitter of which is grounded SGND; A resistor R156, wherein a first terminal of the resistor R156 is connected to the negative electrode of the power supply, and a second terminal of the resistor R156 is connected to the base of the transistor Q24; a resistor R157, wherein a first end of the resistor R157 is connected to a base of the transistor Q24, and a second end of the resistor R157 is connected to an emitter of the transistor Q24; A transistor Q25, the emitter of which is connected to the emitter of the diode Q24; a resistor R160, wherein a first terminal of the resistor R160 is connected to the emitter of the transistor Q25, and a second terminal of the resistor R160 is connected to the base of the transistor Q25; A resistor R159, wherein a first terminal of the resistor R159 is connected to the base of the transistor Q25, and a second terminal of the resistor R159 is connected to the cathode of the speaker BZ1; A diode D35, the diode D35 is connected in parallel with the speaker BZ1, wherein the cathode of the diode D35 is connected to the cathode of the speaker BZ1; A resistor R161, wherein a first terminal of the resistor R161 is connected to a positive electrode of the speaker BZ1; The cathode of the light emitting diode LED1 is connected to the collector of the transistor Q25, and the anode is connected to the second end of the resistor R161; The secondary protection circuit includes an output current overload protection circuit and an output short circuit protection circuit; The output current overload protection circuit comprises: A resistor R132 and a capacitor C61, wherein a first end of the resistor R132 is connected to a CT+ pin of the processor, a second end thereof is connected to a first end of the capacitor C61, and a second end of the capacitor C61 is grounded to SGND; A capacitor C64 connected in parallel with the capacitor C61; Capacitor C62, capacitor C65, capacitor C63, resistor R97, the first ends of the capacitor C62, capacitor C65, and capacitor C63 are connected to each other and to the ground SGND, the second end of the capacitor C62 is connected to the CT+ pin of the processor, the second end of the capacitor C63 is connected to the sampling ground SGND, the first end of the resistor R97 is connected to the sampling ground SGND, and the second end thereof is connected to the second end of the capacitor C65; Capacitor C50, resistor R102, resistor R105, resistor R139, resistor R141, the capacitor C50, resistor R102, resistor R105 are connected in sequence to form a first series circuit, the first end of the first series circuit is connected to the second end of the resistor R97, the second end of the first series circuit is the voltage output end VDD, the first end of the resistor R139 is connected to the second end of the capacitor C65, the second end thereof is connected to the node between the resistor R102 and the resistor R105 and the first end of the resistor R141, and the second end of the resistor R141 is connected to the OVER pin of the processor; A comparator U9B, wherein an inverting input terminal of the comparator U9B is connected to a second terminal of the capacitor C65; A second series circuit formed by a resistor R136, a resistor R138, and a resistor R137 connected in series, wherein a first end of the second series circuit is connected to an inverting input end of a comparator U9B, a second end thereof is connected to a ground pin of a capacitor C61, a circuit node between the resistor R136 and the resistor R138 is connected to a second end of a resistor R132, and a circuit node between the resistor R138 and the resistor R137 is connected to a non-inverting input end of the comparator U9B; A capacitor C66 connected in parallel with the resistor R137; A resistor R140, wherein a first terminal of the resistor R140 is connected to the non-inverting input terminal of the comparator U9B, and a second terminal thereof outputs a voltage VDD; Capacitor C68 and capacitor C70, wherein the first terminal of the capacitor C68 is connected to the output terminal of the comparator U9B and the first terminal of the resistor R141, the second terminal of the capacitor C68 is connected to the ground terminal of the capacitor C61, the first terminal of the capacitor C70 is connected to the second terminal of the resistor R141, and the second terminal thereof is connected to the second terminal of the capacitor C68; The output short-circuit protection circuit comprises: A comparator U9A, wherein the positive power pin of the comparator U9A is connected to the second end of the resistor R105, and the negative power pin of the comparator U9A is connected to the second end of the capacitor C68; Resistor R143, capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77, the second ends of the capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77 are connected to each other and to ground SGND, the first end of the resistor R143 is connected to the CT+ pin of the processor, and the second end thereof is connected to the first end of the capacitor C72, the first end of the resistor R145 is connected to the non-inverting input end of the comparator U9A, the first end of the capacitor C74 is connected to the second end of the resistor R105, the first end of the resistor R149 is connected to the inverting input end of the comparator U9A, the inverting input end of the comparator U9A is also connected to the second end of the resistor R143, and the first end of the capacitor C77 is connected to the output end of the comparator U9A; a resistor R144, wherein a first terminal of the resistor R144 is connected to a second terminal of the resistor R105; Resistor R151, a first end of the resistor R151 is connected to a second end of the resistor R105, and a second end of the resistor R151 is connected to a SHORT pin of the processor and an output end of the comparator U9A.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention adopts a two-level protection structure to protect the transformer. First, a protection device is installed in the distribution box, and the protection device will blow the fuse after overcurrent to disconnect the path. Second, a protection circuit is set in the distribution box as a secondary protection.

[0017] 2. The present invention has made an improved design for the fuse assembly. According to transformers of different powers, corresponding fuse assemblies can be configured. The multiple fuses on the fuse assembly have the function of overcurrent fusing and also have the function of supporting. After the multiple fuses are blown, the conductive rod can be lifted up by the action of the first compression spring, thereby disconnecting the circuit of the protective device.

[0018] 3. The protection mechanism of the present invention is easy to replace. It only requires opening the insulating cover, taking out the blown fuse component, and then replacing it with a new one.

[0019] 4. The present invention is also provided with an audible and visual alarm device, which is powered by an independent power supply and is controlled by a passive switch, that is, after the conductive rod is retracted, the passive switch can be closed to achieve the purpose of reminding the staff. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a structural diagram of the passage state of the protective device of the present invention.

[0021] Figure 2 It is a schematic diagram of the protection mechanism of the present invention.

[0022] Figure 3 It is a schematic structural diagram of the lower pole of the present invention.

[0023] Figure 4 It is a structural schematic diagram of the fuse of the present invention.

[0024] Figure 5 This is a structural diagram of the protective device of the present invention in the circuit-breaking state.

[0025] Figure 6 It is a schematic diagram of the structure of the fuse assembly after it is fused.

[0026] Figure 7 It is a schematic diagram of the power supply structure of the sound and light alarm of the present invention.

[0027] Figure 8It is the circuit diagram of the sound and light alarm device of the present invention.

[0028] Fig. 9 This is the output current overload protection circuit diagram of the present invention.

[0029] Fig.10 This is the output short-circuit protection circuit diagram of the present invention.

[0030] Markings in the accompanying drawings: buckle 1, fuse assembly 2, conductive rod 3, blocking plate 4, protective seat 5, right conductive strip 6, pressure head 7, first compression spring 8, passive switch 9, power supply terminal 10, sound and light alarm device 11, bottom cavity 12, first terminal 13, snap mechanism 14, left conductive strip 15, strip profile 16, card plate 17, power supply 18, first elastic electrode 19, insulating cover 20, insulating member 21, upper pole 22, fuse 23, annular retaining ring 24, lower pole 25, second jack 26, first jack 27, column 28, insulating block 71, hard terminal 91, second compression spring 92, insulating bracket 93, second elastic electrode 94, press key 95, contact terminal 96, glass rod fragments 211, second end pin 231, glass rod 232, easy-swelling liquid 233, resistance wire 234, first end pin 235. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the protection scope of the present invention. Obviously, the embodiments described in the present invention are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Embodiment 1: The specific structure of the present invention is as follows: Please refer to the attached Figure 1-7 The present invention provides a protection device for an electrical engineering distribution transformer, comprising a detachably connected protection seat 5 and a buckle 1, wherein the protection seat 5 has a conductive strip mounting structure in an off-circuit state, and the buckle 1 has a power supply 18 and a protection mechanism; the protection seat 5 is a U-shaped structural member having a U-shaped cavity therein, and the bottom surface of the U-shaped opening of the protection seat 5 is provided with four through holes, which are respectively a first through hole, a second through hole, a third through hole and a fourth through hole; the conductive strip mounting structure in an off-circuit state comprises: A left conductive strip 15, one end of which is fixed to the left cavity of the U-shaped cavity, and the other end of which extends to just below the first through hole. The left conductive strip 15 is fixed by screws, and a terminal matching hole is provided at the extended end thereof; One end of the right conductive bar 6 is fixed to the right cavity of the U-shaped cavity, and the other end extends to just below the second through hole. The right conductive bar 6 is fixed by screws.

[0034] Terminal holes are provided on both sides of the shell of the protection seat 5. The two terminal holes are opposite to the screws on both sides. The copper terminals are connected to the screws and fastened by the screws.

[0035] After the buckle portion 1 is buckled with the protective seat 5, the circuit of the disconnected conductive strip installation structure can be turned on, and the turned-on circuit passes through the protective mechanism; The protection agencies include: A conductive rod telescopic assembly that is telescopic and can be inserted into the protective seat 5. After the conductive rod telescopic assembly is inserted into the protective seat 5, it can contact one of the conductive strips therein. Figure 1 As shown, the conductive rod telescopic assembly extends into the protective seat 5 and contacts the right conductive bar 6; The fuse assembly 2 is pressed against and electrically connected to the conductive rod telescopic assembly so that the conductive rod assembly extends into the protective seat 5, and the fuse assembly has an overcurrent fuse and a length shortening structure; The protection seat 5 is provided with an audible and visual alarm device 11 .

[0036] The buckle portion 1 also has an on-off mechanism capable of conducting the sound and light alarm device 11, and the on-off mechanism includes: A passive switch 9 is provided on the buckle portion 1. After the buckle portion 1 is inserted into the protective seat 5, the passive switch 9 is in electrical contact with the sound and light alarm device 11 and can control the on and off of the sound and light alarm device 11. The passive switch 9 is electrically connected to a power source. The pressure head 7 is fixed on the conductive rod telescopic assembly. When the pressure head 7 is pressed down, the passive switch 9 can be disconnected, and when the pressure head 7 is raised, the passive switch 9 is automatically turned on. The lower end of the pressure head 7 is an insulating block 71.

[0037] The buckle portion 1 comprises: The buckle shell has a battery slot, a straight cavity and an end hole, the first end of the straight cavity is opposite to the second through hole, the second end is connected to the end hole, the side of the straight cavity is provided with a side opening, the power source 18 is a rechargeable battery, and the rechargeable battery is installed in the battery slot; A first elastic electrode 19, disposed in the side opening, the round end of the first elastic electrode 19 is retractable, and the round end is in the straight cavity area; The first terminal 13 is protruding and fixed on the plug end of the buckle shell, and is electrically connected to the first elastic electrode 19. After the buckle part 1 is buckled into the protective seat 5, the first terminal 13 passes through the first through hole and contacts the left conductive strip 15.

[0038] The conductive rod telescopic assembly comprises a conductive rod 3 and a first compression spring 8. The thick section of the conductive rod 3 is in the straight cavity, and the thin section thereof extends to the second through hole. The first compression spring 8 is sleeved on the thin section, with one end thereof abutting against the inner edge of the second through hole, and the other end thereof abutting against the step between the thick section and the thin section. After the conductive rod 3 is pressed against the fuse assembly, its lower end contacts the right conductive bar 6; The pressure head 7 is an insulating pressure head, and one side of the insulating pressure head is fixed to the conductive rod 3 .

[0039] A blocking plate 4 is provided on one side of the straight cavity to limit the upward distance of the pressure head 7. The blocking plate 4 is used to block the pressure head 7 and also blocks the conductive rod 3 from moving upward.

[0040] The fuse assembly comprises: A lower pole 25, one end of which is a flat end, and the flat end forms a contact-type electrical connection with the conductive rod 3, and the other end of the lower pole 25 is provided with an annular retaining ring 24, and the bottom surface of the annular retaining ring 24 is provided with a first jack 27 distributed in a ring array, and a column 28 perpendicular to the flat end is provided at the center of the flat end of the lower pole 25, and the height of the column 28 is less than the annular retaining ring 24; An upper pole 22, the first surface of the upper pole 22 facing the lower pole 25 is provided with second plug holes 26 distributed in a ring array, and after the fuse assembly is positioned, the first elastic electrode 19 contacts the upper pole 22; A plurality of fuses 23, wherein the first end pin 235 of the fuse 23 is inserted into the first plug hole 27, and the second end pin 231 thereof is inserted into the second plug hole 26. When the fuse is blown, when the upper pole 22 is taken out, if the lower pole 25 cannot be taken up, the pole 28 is clamped by pliers to take out the lower pole 25; The insulating member 21 is fixed to the second surface of the upper pole 22 .

[0041] An insulating cover 20 is screwed onto the end hole, and the provision of the insulating cover 20 facilitates replacement of the fuse assembly 2 .

[0042] The fuse 23 also includes a resistance wire assembly; The resistance wire assembly includes: A glass rod 232, both ends of which are connected to the first end pin 235 and the second end pin 231 respectively, and has a cavity inside; The resistance wire 234 is disposed in the cavity, and its two ends are respectively connected to the first end pin 235 and the second end pin 231; The expandable liquid 233 is filled in the cavity. When a normal current passes through the resistance wire 234, the resistance wire 234 generates a low amount of heat, which is insufficient to expand the expandable liquid 233. When a large current passes through the resistance wire 234, it generates a large amount of heat, which is absorbed by the expandable liquid 233. The expandable liquid 233 expands and bursts the glass rod 232. The glass rod 232 breaks, and the glass rod debris 211 formed by the breakage falls into the annular retaining ring 24, preventing the glass rod debris 211 from entering the straight cavity.

[0043] The sound and light alarm device 11 is fixed to the bottom cavity 12 of the U-shaped cavity, and two power supply terminals 10 are arranged on the top of the shell, and the two power supply terminals 10 are respectively opposite to the third through hole and the fourth through hole; The passive switch 9 comprises: An insulating bracket 93 is fixed in the buckle portion 1 and is provided with a contact terminal 96 connected to the positive pole of the power source 18 and a spring column cavity; Two electrical pins fixed to the insulating bracket 93, the two electrical pins can enter the third through hole and the fourth through hole respectively, and make one-to-one contact with the two power supply terminals, and a first electrical pin is electrically connected to the negative electrode of the power supply 18; A second elastic electrode 94 is fixed in the insulating bracket 93, with its non-retractable end electrically connected to the second electrical pin and its retractable end facing the contact terminal 96; A second compression spring 92, disposed in the spring column cavity; A hard terminal 91, wherein a first end of the hard terminal 91 is fixed to an upper end of the second compression spring 92, and a second end of the hard terminal 91 extends to an upper end of the telescopic end and is located below the contact terminal 96; The pressing key 95 is fixed to the first end of the hard terminal 91 , and its outer end extends out of the insulating bracket 93 and faces the pressing head 7 . Embodiment 2:

[0044] The following is the working principle of the protective device of the electrical engineering distribution transformer of the present invention: like Figure 1-7 As shown, Figure 1 The assembled protection device is in the initial state, at which the conductive rod 3 contacts the right conductive strip 6 to form a path, the insulating block 71 on the pressure head 7 is pressed down, so that the pressing key 95 is pressed down, and the pressing key 95 brings the hard terminal 91 to press down the second compression spring 92 and the telescopic end of the second elastic electrode 94, and the hard terminal 91 is disconnected from the contact terminal 96. At this time, the sound and light alarm device 11 is in the disconnected state.

[0045] Specifically, the current enters from the right conductive strip 6 , passes through the conductive rod 3 , the lower pole 25 , the plurality of fuses 23 , the upper pole 22 , the first elastic electrode 19 , the first terminal 13 , and is finally led out from the left conductive strip 15 .

[0046] When the current entering the right conductive strip 6 exceeds the upper limit of the fuses 23, the fuses 23 generate a large amount of heat, which is transferred to the easily expandable liquid 233. The easily expandable liquid 233 expands due to the heat, and the glass rod 232 is broken and falls into the bottom surface of the annular retaining ring 24. At this time, the resistance wire 234 is not enough to support the lower pole 25. The conductive rod 3 is lifted by the first compression spring 8, and the conductive rod 3 is disconnected from the right conductive strip 6, breaking the circuit.

[0047] After the lower pole 25 is lifted up, the annular retaining ring 24 thereon abuts against the lower end of the upper pole 22 .

[0048] As the conductive rod 3 rises, it brings the pressure head 7 up synchronously. After the pressure head 7 rises, the second compression spring 92 lifts the hard terminal 91. After the hard terminal 91 rises, it contacts the contact terminal 96. At the same time, the telescopic end of the second elastic electrode 94 rises and keeps contacting the hard terminal 91. The sound and light alarm device 11 forms a passage, and the speaker and the light emitting diode work synchronously to emit an alarm sound and flashing light, reminding the surrounding staff to handle it.

[0049] Correspondingly, the protection seat 5 is provided with a light-transmitting area for the light of the light emitting diode to pass through. Implementation:3:

[0050] A buckle mechanism 14 is provided at the bottom end of the protection seat 5. The buckle mechanism 14 is used to clamp the mounting plate after the buckle is opened by the action of a return spring.

[0051] The outer corners of both ends of the protection seat 5 are provided with sliding grooves, and a plurality of protection seats 5 are joined together by sliding the strip profiles 16 into the sliding grooves.

[0052] Buckle grooves are provided on both sides of the outer side of the buckle shell, and a clamping plate 17 is provided on the upper end of the protective seat 5. After the buckle part 1 is inserted into the protective seat 5, the clamping plate 17 is clamped into the buckle groove to fix the buckle part 1. Implementation:4:

[0053] The present invention also includes a circuit, which uses the electrical engineering distribution transformer of embodiment 1 to embodiment 3, and includes an audible and visual alarm circuit and a secondary protection circuit; The sound and light alarm circuit comprises: Speaker BZ1, positive pole connected to hard terminal 91; A transistor Q24, the collector of which is connected to the cathode of the speaker BZ1, and the emitter of which is grounded SGND; a resistor R156, wherein a first terminal of the resistor R156 is connected to the negative electrode of the power source 18, and a second terminal of the resistor R156 is connected to the base of the transistor Q24; a resistor R157, wherein a first end of the resistor R157 is connected to a base of the transistor Q24, and a second end of the resistor R157 is connected to an emitter of the transistor Q24; A transistor Q25, the emitter of which is connected to the emitter of the diode Q24; a resistor R160, wherein a first terminal of the resistor R160 is connected to the emitter of the transistor Q25, and a second terminal of the resistor R160 is connected to the base of the transistor Q25; A resistor R159, wherein a first terminal of the resistor R159 is connected to the base of the transistor Q25, and a second terminal of the resistor R159 is connected to the cathode of the speaker BZ1; A diode D35, the diode D35 is connected in parallel with the speaker BZ1, wherein the cathode of the diode D35 is connected to the cathode of the speaker BZ1; A resistor R161, wherein a first terminal of the resistor R161 is connected to a positive electrode of the speaker BZ1; The cathode of the light emitting diode LED1 is connected to the collector of the transistor Q25, and the anode is connected to the second end of the resistor R161; The secondary protection circuit includes an output current overload protection circuit and an output short circuit protection circuit; The output current overload protection circuit comprises: A resistor R132 and a capacitor C61, wherein a first end of the resistor R132 is connected to a CT+ pin of the processor, a second end thereof is connected to a first end of the capacitor C61, and a second end of the capacitor C61 is grounded to SGND; A capacitor C64 connected in parallel with the capacitor C61; Capacitor C62, capacitor C65, capacitor C63, resistor R97, the first ends of the capacitor C62, capacitor C65, and capacitor C63 are connected to each other and to the ground SGND, the second end of the capacitor C62 is connected to the CT+ pin of the processor, the second end of the capacitor C63 is connected to the sampling ground SGND, the first end of the resistor R97 is connected to the sampling ground SGND, and the second end thereof is connected to the second end of the capacitor C65; Capacitor C50, resistor R102, resistor R105, resistor R139, resistor R141, the capacitor C50, resistor R102, resistor R105 are connected in sequence to form a first series circuit, the first end of the first series circuit is connected to the second end of the resistor R97, the second end of the first series circuit is the voltage output end VDD, the first end of the resistor R139 is connected to the second end of the capacitor C65, the second end thereof is connected to the node between the resistor R102 and the resistor R105 and the first end of the resistor R141, and the second end of the resistor R141 is connected to the OVER pin of the processor; A comparator U9B, wherein an inverting input terminal of the comparator U9B is connected to a second terminal of the capacitor C65; A second series circuit formed by a resistor R136, a resistor R138, and a resistor R137 connected in series, wherein a first end of the second series circuit is connected to an inverting input end of a comparator U9B, a second end thereof is connected to a ground pin of a capacitor C61, a circuit node between the resistor R136 and the resistor R138 is connected to a second end of a resistor R132, and a circuit node between the resistor R138 and the resistor R137 is connected to a non-inverting input end of the comparator U9B; A capacitor C66 connected in parallel with the resistor R137; A resistor R140, wherein a first terminal of the resistor R140 is connected to the non-inverting input terminal of the comparator U9B, and a second terminal thereof outputs a voltage VDD; Capacitor C68 and capacitor C70, wherein the first terminal of the capacitor C68 is connected to the output terminal of the comparator U9B and the first terminal of the resistor R141, the second terminal of the capacitor C68 is connected to the ground terminal of the capacitor C61, the first terminal of the capacitor C70 is connected to the second terminal of the resistor R141, and the second terminal thereof is connected to the second terminal of the capacitor C68; The output short-circuit protection circuit comprises: A comparator U9A, wherein the positive power pin of the comparator U9A is connected to the second end of the resistor R105, and the negative power pin of the comparator U9A is connected to the second end of the capacitor C68; Resistor R143, capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77, the second ends of the capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77 are connected to each other and to ground SGND, the first end of the resistor R143 is connected to the CT+ pin of the processor, and the second end thereof is connected to the first end of the capacitor C72, the first end of the resistor R145 is connected to the non-inverting input end of the comparator U9A, the first end of the capacitor C74 is connected to the second end of the resistor R105, the first end of the resistor R149 is connected to the inverting input end of the comparator U9A, the inverting input end of the comparator U9A is also connected to the second end of the resistor R143, and the first end of the capacitor C77 is connected to the output end of the comparator U9A; a resistor R144, wherein a first terminal of the resistor R144 is connected to a second terminal of the resistor R105; Resistor R151, a first end of the resistor R151 is connected to a second end of the resistor R105, and a second end of the resistor R151 is connected to a SHORT pin of the processor and an output end of the comparator U9A.

[0054] The circuit of the present invention is a secondary protection circuit, that is, when a problem occurs in the protection device of embodiments 1-3, the secondary protection circuit can respond in time to prevent the transformer from being damaged.

[0055] In summary, the present invention adopts a two-level protection structure to protect the transformer. First, a protective device is installed in the distribution box. The protective device will blow the fuse after overcurrent to disconnect the path. Second, a protective circuit is set in the distribution box as a secondary protection. The present invention has made an improved design for the fuse assembly. According to the transformers of different powers, corresponding fuse assemblies can be configured. The multiple fuses on the fuse assembly have the function of overcurrent blowing and also have the function of supporting. After the multiple fuses are blown, the conductive rod can be lifted up by the action of the first compression spring, thereby disconnecting the circuit of the protective device. The protective mechanism of the present invention is easy to replace. It only needs to open the insulating cover, take out the fuse assembly after the fuse is blown, and then replace the new fuse assembly. The present invention is also provided with an audible and visual alarm device. The audible and visual alarm device is powered by an independent power supply. The audible and visual alarm device is controlled by a passive switch, that is, after the conductive rod is retracted, the passive switch can be closed to achieve the purpose of reminding the staff.

[0056] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A protective device for a power distribution transformer in an electrical engineering project, comprising a detachably connected protective seat (5) and a buckle (1), wherein the protective seat (5) has a conductive strip mounting structure in an open circuit state, and is characterized in that: The buckle part (1) has a power source (18) and a protection mechanism; After the buckle portion (1) is buckled with the protective seat (5), the circuit of the disconnected conductive strip installation structure can be switched on, and the switched-on circuit passes through the protective mechanism; The protection agencies include: A conductive rod telescopic assembly which is telescopic and can be extended into the protection seat (5), and after the conductive rod telescopic assembly is extended into the protection seat (5), it can contact one of the conductive strips therein; a fuse assembly, which is pressed against and electrically connected to the conductive rod telescopic assembly so that the conductive rod assembly extends into the protective seat (5), and the fuse assembly has an overcurrent fusing and length shortening structure; The protection seat (5) is provided with an audible and visual alarm device (11); The buckle portion (1) also has an on-off mechanism capable of turning on the sound and light alarm device (11), the on-off mechanism comprising: A passive switch (9) is arranged on the buckle portion (1); after the buckle portion (1) is inserted into the protective seat (5), the passive switch (9) is in electrical contact with the sound and light alarm device (11) and can control the on and off of the sound and light alarm device (11); and the passive switch (9) is electrically connected to a power source; A pressure head (7) is fixed laterally to the conductive rod telescopic assembly, and the passive switch (9) can be disconnected when the pressure head (7) is pressed down, and the passive switch (9) is automatically turned on when the pressure head (7) is raised.

2. The protection device for an electrical engineering distribution transformer according to claim 1, characterized in that: The protective seat (5) is a U-shaped structural member having a U-shaped cavity therein, and the bottom surface of the U-shaped opening of the protective seat (5) is provided with four through holes, the four through holes being respectively a first through hole, a second through hole, a third through hole and a fourth through hole; The conductive bar installation structure in the disconnected state includes: A left conductive strip (15), one end of which is fixed to the left cavity of the U-shaped cavity, and the other end of which extends to just below the first through hole; A right conductive strip (6) has one end fixed to the right cavity of the U-shaped cavity and the other end extending to just below the second through hole.

3. The protection device for an electrical engineering distribution transformer according to claim 2, characterized in that: The buckle portion (1) comprises: A buckle shell having a battery slot, a straight cavity and an end hole, wherein a first end of the straight cavity faces the second through hole, and a second end thereof is connected to the end hole, and a side opening is provided on a side of the straight cavity, wherein the power source (18) is a rechargeable battery, and the rechargeable battery is installed in the battery slot; A first elastic electrode (19) is arranged in the side opening, the round end of the first elastic electrode (19) is retractable, and the round end is located in the straight cavity area; The first terminal (13) is protruding and fixed on the plug end of the buckle shell, and is electrically connected to the first elastic electrode (19). After the buckle portion (1) is buckled into the protective seat (5), the first terminal (13) passes through the first through hole and contacts the left conductive strip (15).

4. The protection device for an electrical engineering distribution transformer according to claim 3, characterized in that: The conductive rod telescopic assembly comprises a conductive rod (3) and a first compression spring (8), wherein the thick section of the conductive rod (3) is located in the straight cavity, and the thin section thereof extends to the second through hole, and the first compression spring (8) is sleeved on the thin section, with one end of the first compression spring abutting against the inner edge of the second through hole, and the other end of the first compression spring abutting against the step between the thick section and the thin section; After the conductive rod (3) is pressed against the fuse assembly, its lower end contacts the right conductive bar (6); The pressure head (7) is an insulating pressure head, and one side of the insulating pressure head is fixed to the conductive rod (3).

5. The protection device for an electrical engineering distribution transformer according to claim 4, characterized in that: A blocking plate (4) is provided on one side of the straight cavity for limiting the upward distance of the pressure head (7).

6. The protection device for an electrical engineering distribution transformer according to claim 4, characterized in that: The fuse assembly comprises: A lower pole (25), one end of the lower pole (25) being a flat end, the flat end forming a contact-type electrical connection with the conductive rod (3), the other end of the lower pole (25) being provided with an annular retaining ring (24), the bottom surface of the annular retaining ring (24) being provided with first jacks (27) distributed in a ring array; an upper pole (22), wherein the first surface of the upper pole (22) facing the lower pole (25) is provided with second plug holes (26) distributed in a ring array, and after the fuse assembly is positioned, the first elastic electrode (19) contacts the upper pole (22); A plurality of fuses (23), wherein the first end pin (235) of the fuse (23) is inserted into the first plug hole (27), and the second end pin (231) of the fuse (23) is inserted into the second plug hole (26); An insulating member (21) is fixed to the second surface of the upper pole (22).

7. The protection device for an electrical engineering distribution transformer according to claim 6, characterized in that: An insulating cover (20) is screwed onto the end hole.

8. The protection device for an electrical engineering distribution transformer according to claim 6, characterized in that: The fuse (23) also includes a resistance wire assembly; The resistance wire assembly includes: A glass rod (232), two ends of which are respectively connected to the first end pin (235) and the second end pin (231), and an interior of which has a cavity; A resistance wire (234), the resistance wire (234) being disposed in the cavity, and having two ends respectively connected to a first end pin (235) and a second end pin (231); The easily expandable liquid (233) is filled in the cavity.

9. The protection device for an electrical engineering distribution transformer according to claim 2, characterized in that: The sound and light alarm device (11) is fixed to the bottom cavity of the U-shaped cavity, and two power supply terminals are provided on the top of the shell, and the two power supply terminals are respectively opposite to the third through hole and the fourth through hole; The passive switch (9) comprises: An insulating bracket (93) is fixed in the buckle portion (1), and is provided with a contact terminal (96) connected to the positive electrode of the power source (18) and a spring column cavity; two electrical pins fixed to the insulating bracket (93), the two electrical pins being capable of respectively entering the third through hole and the fourth through hole and making one-to-one contact with the two power supply terminals, wherein a first electrical pin is electrically connected to the negative electrode of the power supply (18); A second elastic electrode (94) is fixed in the insulating bracket (93), a non-retractable end thereof is electrically connected to the second electrical pin, and a retractable end thereof faces the contact terminal (96); A second compression spring (92) is disposed in the spring column cavity; a hard terminal (91), wherein a first end of the hard terminal (91) is fixedly connected to the upper end of the second compression spring (92), and a second end of the hard terminal (91) extends to the upper end of the telescopic end and is located below the contact terminal (96); A pressing key (95) is fixed to the first end of the hard terminal (91), and an outer end thereof extends out of the insulating bracket (93) and faces the pressing head (7).

10. A circuit, characterized in that: The circuit is applied to the electrical engineering distribution transformer according to any one of claims 1 to 9, and the circuit includes an audible and visual alarm circuit and a secondary protection circuit; The sound and light alarm circuit comprises: Speaker BZ1, positive pole connected to hard terminal (91); A transistor Q24, the collector of which is connected to the cathode of the speaker BZ1, and the emitter of which is grounded SGND; a resistor R156, wherein a first terminal of the resistor R156 is connected to the negative electrode of the power supply (18), and a second terminal of the resistor R156 is connected to the base of the transistor Q24; a resistor R157, wherein a first end of the resistor R157 is connected to a base of the transistor Q24, and a second end of the resistor R157 is connected to an emitter of the transistor Q24; A transistor Q25, the emitter of which is connected to the emitter of the diode Q24; a resistor R160, wherein a first terminal of the resistor R160 is connected to the emitter of the transistor Q25, and a second terminal of the resistor R160 is connected to the base of the transistor Q25; A resistor R159, wherein a first terminal of the resistor R159 is connected to the base of the transistor Q25, and a second terminal of the resistor R159 is connected to the cathode of the speaker BZ1; A diode D35, the diode D35 is connected in parallel with the speaker BZ1, wherein the cathode of the diode D35 is connected to the cathode of the speaker BZ1; A resistor R161, wherein a first terminal of the resistor R161 is connected to a positive electrode of the speaker BZ1; The cathode of the light emitting diode LED1 is connected to the collector of the transistor Q25, and the anode is connected to the second end of the resistor R161; The secondary protection circuit includes an output current overload protection circuit and an output short circuit protection circuit; The output current overload protection circuit comprises: A resistor R132 and a capacitor C61, wherein a first end of the resistor R132 is connected to a CT+ pin of the processor, a second end thereof is connected to a first end of the capacitor C61, and a second end of the capacitor C61 is grounded to SGND; A capacitor C64 connected in parallel with the capacitor C61; Capacitor C62, capacitor C65, capacitor C63, resistor R97, the first ends of the capacitor C62, capacitor C65, and capacitor C63 are connected to each other and to the ground SGND, the second end of the capacitor C62 is connected to the CT+ pin of the processor, the second end of the capacitor C63 is connected to the sampling ground SGND, the first end of the resistor R97 is connected to the sampling ground SGND, and the second end thereof is connected to the second end of the capacitor C65; Capacitor C50, resistor R102, resistor R105, resistor R139, resistor R141, the capacitor C50, resistor R102, resistor R105 are connected in sequence to form a first series circuit, the first end of the first series circuit is connected to the second end of the resistor R97, the second end of the first series circuit is the voltage output end VDD, the first end of the resistor R139 is connected to the second end of the capacitor C65, the second end thereof is connected to the node between the resistor R102 and the resistor R105 and the first end of the resistor R141, and the second end of the resistor R141 is connected to the OVER pin of the processor; A comparator U9B, wherein an inverting input terminal of the comparator U9B is connected to a second terminal of the capacitor C65; A second series circuit formed by a resistor R136, a resistor R138, and a resistor R137 connected in series, wherein a first end of the second series circuit is connected to an inverting input end of a comparator U9B, a second end thereof is connected to a ground pin of a capacitor C61, a circuit node between the resistor R136 and the resistor R138 is connected to a second end of a resistor R132, and a circuit node between the resistor R138 and the resistor R137 is connected to a non-inverting input end of the comparator U9B; A capacitor C66 connected in parallel with the resistor R137; A resistor R140, wherein a first terminal of the resistor R140 is connected to the non-inverting input terminal of the comparator U9B, and a second terminal thereof outputs a voltage VDD; Capacitor C68 and capacitor C70, wherein the first terminal of the capacitor C68 is connected to the output terminal of the comparator U9B and the first terminal of the resistor R141, the second terminal of the capacitor C68 is connected to the ground terminal of the capacitor C61, the first terminal of the capacitor C70 is connected to the second terminal of the resistor R141, and the second terminal thereof is connected to the second terminal of the capacitor C68; The output short-circuit protection circuit comprises: A comparator U9A, wherein the positive power pin of the comparator U9A is connected to the second end of the resistor R105, and the negative power pin of the comparator U9A is connected to the second end of the capacitor C68; Resistor R143, capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77, the second ends of the capacitor C72, resistor R145, capacitor C74, capacitor C149 and capacitor C77 are connected to each other and to ground SGND, the first end of the resistor R143 is connected to the CT+ pin of the processor, and the second end thereof is connected to the first end of the capacitor C72, the first end of the resistor R145 is connected to the non-inverting input end of the comparator U9A, the first end of the capacitor C74 is connected to the second end of the resistor R105, the first end of the resistor R149 is connected to the inverting input end of the comparator U9A, the inverting input end of the comparator U9A is also connected to the second end of the resistor R143, and the first end of the capacitor C77 is connected to the output end of the comparator U9A; a resistor R144, wherein a first terminal of the resistor R144 is connected to a second terminal of the resistor R105; Resistor R151, a first end of the resistor R151 is connected to a second end of the resistor R105, and a second end of the resistor R151 is connected to a SHORT pin of the processor and an output end of the comparator U9A.

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