Contactor protection device

Abstract

The utility model discloses a contactor protection device, comprising three temperature detection type alarm trigger circuits which are arranged corresponding to three phases of a contactor and are connected to an alarm assembly, and a temperature detection end of one temperature detection type alarm trigger circuit is correspondingly connected to an upper moving contact and a lower moving contact of one phase of the contactor; the three temperature detection type tripping trigger circuits are arranged corresponding to three phases of the contactor and are connected to a contactor protection tripping normally-closed contact, and the temperature detection end of one temperature detection type tripping trigger circuit is correspondingly connected to an upper moving contact and a lower moving contact of one phase of the contactor.

Description

Technical Field

[0001] The utility model relates to the technical field of contactors, in particular to a contactor protection device. Background Art

[0002] In common AC contactor circuits, prolonged arcing between the moving and static contacts during operation increases contact resistance. If not detected promptly, this can lead to contact oxidation, a sharp increase in contact resistance, and a phase loss in the load that can damage equipment. In severe cases, the contactor can catch fire, causing electrical fires. Mechanical vibration often causes loose connections at the upper and lower terminals, leading to burnout and failure of the contactor. In the early stages of these faults, current and voltage levels appear normal, and they develop rapidly, making them difficult to monitor effectively. Currently, detection relies entirely on regular inspections by electrical inspectors, often by the time they are discovered, serious consequences have already occurred. Utility Model Content

[0003] In view of the above technical problems, the utility model provides a contactor protection device.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present utility model is as follows:

[0005] A contactor protection device, comprising:

[0006] Three temperature detection alarm trigger circuits are provided corresponding to the three phases of the contactor and are connected to the alarm component, wherein the temperature detection end of one temperature detection alarm trigger circuit is correspondingly connected to the upper moving contact and the lower moving contact of one phase of the contactor;

[0007] Three temperature detection trip trigger circuits are provided corresponding to the three phases of the contactor and are connected to the normally closed contacts of the contactor protection trip. Among them, the temperature detection end of one temperature detection trip trigger circuit is correspondingly connected to the upper moving contact and the lower moving contact of one phase of the contactor.

[0008] The temperature detection alarm trigger circuit includes:

[0009] a first alarm temperature control switch and a second alarm temperature control switch;

[0010] Among them, one end of the first alarm temperature control switch and the second alarm temperature control switch are respectively connected to the upper moving contact and the lower moving contact of one phase of the contactor, and the other ends are connected in parallel and then connected to the first coil of the alarm relay through the first dedicated soft connecting wire and the first plug pin. The first coil is connected to the first voltage dividing resistor, the first voltage dividing resistor is connected to the second plug pin, the second plug pin is connected to the second dedicated soft connecting wire, the second dedicated soft connecting wire is connected to the upper moving contact and the lower moving contact of another phase, and so on to form a loop.

[0011] The normally open contacts of the alarm relay on each temperature detection alarm trigger circuit are connected in parallel to the normally open contacts of the contactor protection alarm.

[0012] The temperature detection type trip trigger circuit includes:

[0013] A first trip temperature control switch and a second trip temperature control switch;

[0014] One end of the first trip temperature-controlled switch and the second trip temperature-controlled switch are respectively connected to the upper moving contact and the lower moving contact of one phase of the contactor, and the other ends are connected in parallel and then connected to the second coil of the trip relay through a third dedicated flexible connecting wire and a third plug pin, the second coil is connected to the second voltage-dividing resistor, the second voltage-dividing resistor is connected to the second plug pin, the second plug pin is connected to the second dedicated flexible connecting wire, the second dedicated flexible connecting wire is connected to the upper moving contact and the lower moving contact of the other phase, and so on to form a loop;

[0015] The normally closed contact of the second coil of each temperature detection type trip trigger circuit is connected in series with the normally closed contact of the contactor protection trip.

[0016] The beneficial effects of the utility model are:

[0017] 1. The utility model fixes two sets of temperature-controlled switches above the moving contact of the contactor, one set controlling the alarm circuit and the other controlling the trip circuit, with the voltage between the moving contacts serving as the operating power source. When the contactor is closed and in normal working condition, the moving and static contacts are in good contact, the contact temperature is normal, the two sets of temperature-controlled switches are both in the disconnected state, and the entire circuit is also in the disconnected state; when the contact resistance of the moving and static contacts increases, the temperature of the contact area rises rapidly. When the temperature exceeds the temperature limit of the temperature-controlled switch, the alarm temperature-controlled switch connected in series with the alarm circuit conducts, energizing the alarm relay, which issues an alarm signal. When the temperature continues to rise, the trip temperature-controlled switch connected in series with the trip circuit conducts, energizing the trip relay, and the normally closed contact of the trip relay is disconnected or the normally open contact is connected, disconnecting the contactor control circuit to prevent further development of the accident.

[0018] 2. The utility model can well protect the contactor in operation and reduce the fire accidents caused by contactor ignition due to contact heating;

[0019] 3. The utility model can avoid the problem of phase loss operation of the equipment caused by poor contact due to heating of the contactor contacts.

[0020] 4. This utility model offers high reliability. The alarm and trip temperature switches function as backup contacts. Even if one is damaged while the other remains intact, the circuit can still be connected, generating an alarm or trip signal. In extreme cases, if all the temperature switches attached to the upper contact of a phase's moving contactor fail (i.e., both the alarm and trip temperature switches are disconnected or malfunctioning), and the upper contact of this moving contactor overheats abnormally, the alarm and trip circuits connected to it will not activate properly. However, because the moving contactor is a metal conductor with good thermal conductivity, heat from the upper contact of the moving contactor accumulates and transfers through the middle of the moving contactor to the lower contact. When the temperature reaches a certain level, the alarm and trip temperature switches attached to the lower contact of the moving contactor can still activate the alarm and trip relays, disconnecting the main circuit. Similarly, if the temperature switch attached to the lower contact of the moving contactor fails, the temperature switch attached to the upper contact of the moving contactor will also activate the alarm and trip relays after a delay, thus providing backup for these extreme situations.

[0021] 5. This utility model provides a certain level of early warning for loose connection issues in contactor terminals. Since the other side of the contactor's static contact is directly connected to the terminal, when the terminal is loosely connected and generates heat, the accumulated heat at the terminal is transferred to the contact, causing the contact temperature to rise. This in turn triggers the alarm relay, which issues an alarm signal, notifying the operator to check. In extreme cases, the trip relay can also be triggered, issuing a trip signal.

[0022] 6. The utility model has a simple structure. The protection device is composed of only temperature control switches, ordinary resistors, plugs, relays and other original components. It has a simple structure, is easy to maintain, has strong anti-electromagnetic interference ability, and can work under various harsh conditions.

[0023] 7. This utility model saves energy and has no standby power consumption. When the contactor is disconnected, the protection circuit is simultaneously shut down. After the contactor is closed, when the circuit is operating normally, the temperature control switch is in the off state and no current flows. The circuit is put into operation only when the contactor contacts generate abnormal heat, and after a period of operation, it shuts down along with the faulty main circuit.

[0024] 8. This utility model offers excellent safety. Even if the temperature control switch breaks down and shorts, the voltage in the protection circuit will not flow into the control circuit, thus ensuring the safety of the control circuit components. (If the temperature control switch breaks down and shorts, the alarm relay or trip relay may malfunction. If the contactor temperature is tested on-site and no abnormalities are found, simply short-circuit the alarm or trip signal circuit, start the contactor normally, and replace the temperature control switch after shutdown.) BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0026] Figure 1It is a principle diagram of the present utility model. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. Furthermore, descriptions of known structures and technologies are omitted in the following description to avoid unnecessary confusion regarding the concepts of the present invention.

[0028] like Figure 1 As shown, a contactor protection device includes: three temperature detection alarm trigger circuits, which are provided corresponding to the three phases of the contactor and connected to the alarm component, wherein the temperature detection end of one temperature detection alarm trigger circuit is correspondingly connected to the upper moving contact 3 and the lower moving contact 4 of one phase of the contactor; three temperature detection trip trigger circuits, which are provided corresponding to the three phases of the contactor and connected to the contactor protection trip normally closed contact 20, wherein the temperature detection end of one temperature detection trip trigger circuit is correspondingly connected to the upper moving contact 3 and the lower moving contact 4 of one phase of the contactor.

[0029] Wherein, the temperature detection type alarm trigger circuit includes: a first alarm temperature control switch 5-2 and a second alarm temperature control switch 6-2;

[0030] Among them, one end of the first alarm temperature control switch 5-2 and the second alarm temperature control switch 6-2 are respectively connected to the upper moving contact 3 and the lower moving contact 4 of one phase of the contactor, and the other ends are connected in parallel and then connected to the first coil 13 of the alarm relay 10 through the first dedicated soft connecting line 7 and the first plug pin 9-1. The first coil 13 is connected to the first voltage dividing resistor 16, the first voltage dividing resistor 16 is connected to the second plug pin 9-3, the second plug pin 9-3 is connected to the second dedicated soft connecting line 18, and the second dedicated soft connecting line 18 is connected to the upper moving contact 3 and the lower moving contact 4 of another phase, and so on to form a loop.

[0031] The normally open contacts 12 of the alarm relay 10 on each temperature detection alarm trigger circuit are connected in parallel to the normally open contact 19 of the contactor protection alarm.

[0032] Wherein, the temperature detection type trip trigger circuit includes: a first trip temperature controlled switch 5-1 and a second trip temperature controlled switch 6-1;

[0033] Among them, one end of the first trip temperature-controlled switch 5-1 and the second trip temperature-controlled switch 6-1 are respectively connected to the upper moving contact 3 and the lower moving contact 4 of one phase of the contactor, and the other ends are connected in parallel and then connected to the second coil 15 of the trip relay 11 through the third dedicated flexible connecting line 8 and the third plug pin 9-2. The second coil 15 is connected to the second voltage-dividing resistor 17, the second voltage-dividing resistor 17 is connected to the second plug pin 9-3, the second plug pin 9-3 is connected to the second dedicated flexible connecting line 18, and the second dedicated flexible connecting line 18 is connected to the upper moving contact 3 and the lower moving contact 4 of the other phase, and so on to form a loop;

[0034] The normally closed contact 14 of the second coil 15 of each temperature detection type trip trigger circuit is connected in series with the normally closed contact 20 of the contactor protection trip.

[0035] When the utility model is in use:

[0036] When the protection circuit is in the energized state, the working principle of the A phase protection circuit is:

[0037] Under normal circumstances, there is good contact between the upper static contact 1 and the upper moving contact 3 of phase A, and between the lower static contact 2 and the lower moving contact 4, and there is no heat generation. Although there is a line voltage UAB between the first tripping temperature-controlled switch 5-1, the first alarm temperature-controlled switch 5-2, the second tripping temperature-controlled switch 6-1, the second alarm temperature-controlled switch 6-2 connected to the moving contact of phase A and the second dedicated soft connecting line 18 connected to the moving contact of phase B, due to the room temperature, the first tripping temperature-controlled switch 5-1, the first alarm temperature-controlled switch 5-2, the second tripping temperature-controlled switch 6-1 and the second alarm temperature-controlled switch 6-2 at the moving contact of phase A are all in the disconnected state, and the protection circuit is also in the disconnected state.

[0038] When the upper moving contact 3 of phase A and the upper static contact 1 of phase A have poor contact or increased contact resistance, both the upper moving contact 3 and the upper static contact 1 begin to heat up, causing the temperature of the upper moving contact 3 to rise. As the temperature continues to rise, when the temperature rises to a certain value (adjustable), the first alarm temperature control switch 5-2 is turned on first. Under the action of the line voltage UAB, current flows from the upper moving contact 3 of phase A through the first alarm temperature control switch 5-2 and the first dedicated flexible connecting line 7 into the first plug pin 9-1, and then the first plug pin 9-1 leads the current to the external circuit and connects to the first coil 13 of the alarm relay 10. The first coil 13 is energized, and the current flows out of the first coil 13, is divided by the first voltage divider resistor 16, and flows into the second plug pin 9-3. Then, it flows back to the internal circuit from the second plug pin 9-3 and flows into the moving contact of phase B through the second dedicated flexible connecting line 18. Because the first coil 13 is energized, the alarm relay 10 is attracted, its normally open contact 12 (dry node) is closed, and an alarm signal is issued.

[0039] If the temperature continues to rise to the limit value (adjustable), the first tripping temperature-controlled switch 5-1 is turned on. Under the action of the line voltage UAB, the current flows from the upper moving contact 3 of phase A through the first tripping temperature-controlled switch 5-1 and the third dedicated flexible connecting line 8 into the third plug pin 9-2, and then the third plug pin 9-2 leads the current to the external circuit, the second coil 15 of the tripping relay 11, the second coil 15 is energized, and the current flows out from the second coil 15 and is divided by the second voltage-dividing resistor 17, and flows into the second plug pin 9-3, and then flows back to the internal circuit from the second plug pin 9-3, and flows into the B phase moving contact through the second dedicated flexible connecting line 18; because the second coil 15 is energized, the tripping relay 11 is energized, and its normally closed contact 14 (dry node) is disconnected, and a tripping signal is issued.

[0040] Similarly, when the lower moving contact 4 of phase A and the lower static contact 2 of phase A have poor contact or increased contact resistance, causing the temperature to continue to rise, the second alarm temperature-controlled switch 6-2 and the second trip temperature-controlled switch 6-1 fixed at the lower moving contact 4 are turned on successively, and the alarm relay 10 and the trip relay 11 are energized and attracted in turn, issuing alarm and trip signals.

[0041] Among them, the working principle of the B-phase and C-phase protection circuits is the same as the working principle of the above-mentioned A-phase protection circuit.

[0042] Alarm output: The normally open contacts 12 of the alarm relays for phases A, B, and C are connected in parallel to form a contactor alarm output. Abnormal heating of any phase's moving contact generates a contactor alarm output signal (dry contact). An external alarm circuit is connected to generate an alarm message.

[0043] Trip output: The normally closed contacts 14 of the trip relays for phases A, B, and C are connected in series to form a contactor trip output. Abnormal heating of the moving contact of any phase generates a contactor trip output signal (dry contact). Disconnect the main circuit after connecting to an external control circuit.

[0044] Note 1: The setting values ​​of the first alarm temperature control switch 5-2 and the second alarm temperature control switch 6-2 should be lower than the setting values ​​of the first trip temperature control switch 5-1 and the second trip temperature control switch 6-1.

[0045] Note 2: The first voltage-dividing resistor 16 and the second voltage-dividing resistor 17 are used to reduce the voltage borne by the coil and should be matched according to the impedance of the relay coil.

[0046] Note 3: The temperature control switch can be fixed to the surface of the moving contact with a high-temperature resistant adhesive, or it can be fixed to the moving contact with a corresponding size by reserving a position in the moving contact while ensuring electrical and mechanical strength, and using a snap to embed the temperature control switch in the moving contact.

[0047] Note 4: For small contactors, trip temperature control switches can be installed only on both sides of the moving contact to save costs and reduce the size of the protection circuit.

[0048] It should be understood that the above-described specific embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the scope of protection of the present invention. In addition, the appended claims of the present invention are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A contactor protection device, characterized in that: include: Three temperature detection alarm trigger circuits are provided corresponding to the three phases of the contactor and are connected to the alarm component, wherein the temperature detection end of one temperature detection alarm trigger circuit is connected to the upper moving contact (3) and the lower moving contact (4) of one phase of the contactor; Three temperature detection type trip trigger circuits are provided corresponding to the three phases of the contactor and are connected to the contactor protection trip normally closed contact (20), wherein the temperature detection end of one temperature detection type trip trigger circuit is correspondingly connected to the upper moving contact (3) and the lower moving contact (4) of one phase of the contactor.

2. A contactor protection device according to claim 1, characterized in that: The temperature detection alarm trigger circuit includes: A first alarm temperature control switch (5-2) and a second alarm temperature control switch (6-2); One end of the first alarm temperature control switch (5-2) and the second alarm temperature control switch (6-2) are respectively connected to the upper moving contact (3) and the lower moving contact (4) of one phase of the contactor, and the other ends are connected in parallel and then connected to the first coil (13) of the alarm relay (10) through the first dedicated soft connecting wire (7) and the first plug pin (9-1), the first coil (13) is connected to the first voltage dividing resistor (16), the first voltage dividing resistor (16) is connected to the second plug pin (9-3), the second plug pin (9-3) is connected to the second dedicated soft connecting wire (18), the second dedicated soft connecting wire (18) is connected to the upper moving contact (3) and the lower moving contact (4) of the other phase, and so on to form a loop; The normally open contacts (12) of the alarm relay (10) on each temperature detection alarm trigger circuit are connected in parallel to the normally open contact (19) of the contactor protection alarm.

3. A contactor protection device according to claim 1, characterized in that: The temperature detection type trip trigger circuit includes: A first tripping temperature control switch (5-1) and a second tripping temperature control switch (6-1); One end of the first trip temperature control switch (5-1) and the second trip temperature control switch (6-1) are respectively connected to the upper moving contact (3) and the lower moving contact (4) of one phase of the contactor, and the other ends are connected in parallel and then connected to the second coil (15) of the trip relay (11) through the third dedicated soft connecting wire (8) and the third plug pin (9-2), the second coil (15) is connected to the second voltage dividing resistor (17), the second voltage dividing resistor (17) is connected to the second plug pin (9-3), the second plug pin (9-3) is connected to the second dedicated soft connecting wire (18), the second dedicated soft connecting wire (18) is connected to the upper moving contact (3) and the lower moving contact (4) of the other phase, and so on to form a loop; The normally closed contact (14) of the second coil (15) of each temperature detection type trip trigger circuit is connected in series with the normally closed contact (20) of the contactor protection trip.

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