Electric leakage lockout parallel operation device of coal mine explosion-proof vacuum starter

Abstract

The utility model belongs to the technical field of parallel operation of starters, and aims to solve the problem that when the starters are used in parallel, leakage latching protection loops of two parallel starters must be cut off at the same time, otherwise, the parallel hot standby operation of the two starters cannot be ensured. According to the leakage lockout parallel operation device of the coal mine explosion-proof vacuum starter, carrier frequency signals generated by a self-excited oscillator on a circuit board I are output through two paths, one path is processed and then coupled with a three-phase power grid, and the other path is amplified and then controls a relay J1 on the circuit board I to be closed; a carrier frequency signal generated by a self-excited oscillator on the circuit board II is output through two paths, one path is processed and then coupled with a three-phase power grid, and the other path is amplified and then controls a relay J2 on the circuit board II to be closed. After the starter is normally started, the earth leakage lockout loop of the starter is cut off while the earth leakage lockout loop of the starter is cut off, and it can be guaranteed that earth leakage lockout protection does not need to be thrown away in the parallel state of the starters.

Description

Technical Field

[0001] This utility model belongs to the field of parallel operation technology of starters, specifically relating to a leakage current interlocking parallel operation device for explosion-proof vacuum starters in coal mines. Background Technology

[0002] In underground coal mines, some key equipment has long adopted a starter-on-standby mode to ensure its safe and efficient operation.

[0003] While this operating mode can promptly start another starter if one starter malfunctions, it also has a drawback: the leakage current interlocking protection cannot function properly. The current solution is to add a feeder switch upstream as leakage current protection, but this conflicts with coal mine safety regulations and must be reformed.

[0004] By analyzing the starter's operating principle diagram, it was discovered that the fundamental reason for the loss of leakage current interlock is that the leakage current interlock protection circuit must be disconnected after the starter starts. This task is accomplished by the vacuum contactor in the starter, which assists in the normally closed contact. However, in the parallel starter configuration, one starter can only disconnect its own leakage current interlock, not the leakage current interlock protection circuit of the starter connected in parallel, and vice versa. This means that if starters are to be used in parallel, the leakage current interlock protection circuits of both parallel starters must be disconnected simultaneously; otherwise, the normal operation of both starters cannot be guaranteed.

[0005] In this situation, after one starter starts, it only disconnects its own leakage current blocking circuit, while the leakage current blocking circuit of the other starter connected in parallel remains connected. This will cause the upstream power supply switch to trip. Utility Model Content

[0006] In order to solve at least one of the above-mentioned technical problems in the prior art, this utility model provides a leakage current interlocking parallel operation device for explosion-proof vacuum starters in coal mines.

[0007] This utility model is achieved using the following technical solution: a parallel operation device for leakage current interlocking of a coal mine explosion-proof vacuum starter, comprising a starter I and a starter II arranged in parallel, with circuit boards I and II respectively added inside starter I and starter II, and circuit boards I and II connected in parallel to a three-phase power grid; circuit boards I and II have self-excited oscillators, wherein the carrier frequency signal generated by the self-excited oscillator on circuit board I is output through two paths, one of which is processed and coupled to the three-phase power grid, and the other is amplified and used to control the relay J1 on circuit board I to activate; The carrier frequency signal generated by the self-excited oscillator on circuit board II is output through two paths. One path is processed and coupled to the three-phase power grid, while the other path is amplified and used to control the relay J2 on circuit board II to engage. The normally open contact of relay J1 is connected in series with the leakage protection circuit of starter I, and the normally open contact of relay J2 is connected in series with the leakage protection circuit of starter II. The series circuit I consisting of the normally open contact KM1 of the vacuum contactor of starter I and a capacitor, and the series circuit II consisting of the normally open contact KM2 of the vacuum contactor of starter II and a capacitor are both connected to the three-phase power grid.

[0008] Preferably, the self-excited oscillator includes a transistor BG, an inductor L1, capacitors C5 and C6, and a resistor R2. The self-excited oscillator provides stable voltage through the voltage regulation circuit of the three-phase power grid. The self-excited oscillator is a three-point self-excited oscillator used to generate a 20KHz carrier frequency signal. When the isolation reversing switch of the starter is powered on, the corresponding self-excited oscillator generates a carrier frequency signal.

[0009] Preferably, one of the carrier frequency signals is coupled to a 660V / 1140V three-phase power grid via a circuit consisting of inductor L2, resistors R3 and R4, and capacitors C7 and C8.

[0010] Preferably, another path of the carrier frequency signal is amplified by three sets of amplifying elements and then output to the corresponding relay J1 or relay J2.

[0011] Preferably, the series circuit I consisting of the normally open contact KM1 of the vacuum contactor of starter I and the capacitor, and the series circuit II consisting of the normally open contact KM2 of the vacuum contactor of starter II and the capacitor are both used to short-circuit the oscillation circuit where the self-excited oscillator is located, so that relays J1 and J2 are disconnected, thereby cutting off the leakage current lockout protection circuit of starter I and starter II.

[0012] Compared with the prior art, the beneficial effects of this utility model are:

[0013] After the starter of this application starts normally, it cuts off its own leakage current lockout circuit while simultaneously cutting off the leakage current lockout circuit of another starter, which can ensure that the leakage current lockout protection does not have to be disconnected when the starters are connected in parallel. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram showing the positions of the normally open contacts of relays J1 and J2 in this embodiment;

[0016] Figure 2 This is a schematic diagram of the oscillation circuit in this embodiment. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described in conjunction with the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other implementation methods obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0018] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this utility model can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should fall within the scope of the technical content disclosed in this utility model. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0019] This utility model provides an embodiment:

[0020] like Figure 1 , Figure 2As shown, a parallel operation device for leakage current interlocking of explosion-proof vacuum starters in coal mines includes starter I and starter II arranged in parallel. Circuit boards I and II are respectively added inside starter I and starter II, and circuit boards I and II are connected in parallel to a three-phase power grid. Circuit boards I and II have self-excited oscillators. The carrier frequency signal generated by the self-excited oscillator on circuit board I is output through two paths: one path is processed and coupled to the three-phase power grid, and the other path is amplified and used to control the relay J1 on circuit board I to activate; the circuit board II has... The carrier frequency signal generated by the self-excited oscillator is output through two channels. One channel is processed and coupled to the three-phase power grid, while the other channel is amplified and used to activate relay J2 on circuit board II. The normally open contact of relay J1 is connected in series with the leakage protection circuit of starter I, and the normally open contact of relay J2 is connected in series with the leakage protection circuit of starter II. The series circuit I consisting of the normally open contact KM1 of the vacuum contactor of starter I and a capacitor, and the series circuit II consisting of the normally open contact KM2 of the vacuum contactor of starter II and a capacitor are both connected to the three-phase power grid.

[0021] In this embodiment, to ensure the normal operation of the leakage current interlocking of the two starters in parallel operation mode, a circuit is designed to guarantee normal operation. Its normally open contact closes to connect the leakage current interlocking circuit. After a starter starts normally, it not only disconnects its own leakage current interlocking circuit but also disconnects the leakage current interlocking circuit of the other starter. This ensures that the leakage current interlocking protection is not tripped in the parallel operation of the starters. Under power-on conditions, the relay normally engages, connecting the leakage current interlocking circuit. The starter normally performs leakage current detection on the load side. As long as one starter engages, its vacuum contactor's normally open contact will close, shorting the capacitor in the oscillation circuit. The corresponding relays for both starters will then disconnect, disconnecting the leakage current interlocking of both starters and ensuring normal starter operation.

[0022] The self-excited oscillator includes transistor BG, inductor L1, capacitors C5 and C6, and resistor R2. The oscillator receives stable voltage from the three-phase power grid's voltage regulation circuit. It is a three-point self-excited oscillator used to generate a 20kHz carrier frequency signal. When the starter's isolation reversing switch is energized, the corresponding self-excited oscillator generates the carrier frequency signal. One path of the carrier frequency signal is coupled to the 660V / 1140V three-phase power grid via a circuit composed of inductor L2, resistors R3 and R4, and capacitors C7 and C8. The other path of the carrier frequency signal is amplified by three sets of amplifier elements and output to the corresponding relay J1 or relay J2.

[0023] The series circuit I consisting of the normally open contact KM1 of the vacuum contactor of starter I and the capacitor, and the series circuit II consisting of the normally open contact KM2 of the vacuum contactor of starter II and the capacitor, are both used to short-circuit the oscillation circuit where the self-excited oscillator is located, so that relays J1 and J2 are disconnected, thereby cutting off the leakage current lockout protection circuit of starter I and starter II.

[0024] Working principle:

[0025] This circuit employs carrier frequency protection. Its principle is that as long as the starter isolation reversing switch is energized, a fixed frequency carrier signal is always present in its circuit: the relay operates, connecting the leakage current interlocking circuit; once either of the two starters operates, the carrier signal is first short-circuited through the starter's KM1 or KM2 contacts. At this point, the detection section determines the disappearance of the carrier signal, the relay stops operating, and the leakage current interlocking circuit of both starters is disconnected. The specific process is as follows:

[0026] The self-excited oscillator generates a 20kHz carrier frequency signal, which is output in two ways: one is coupled to a 660V / 1140V three-phase power grid via inductors L2, R3, R4, C7, and C8; the other is amplified by components 339, 324, and 324 before being output as a sampling signal for the detection system circuit. Under normal circumstances, the system circuit has a high level of network insulation due to the absence of any open circuit, the load on the oscillator is very small, and the output voltage across C9 is relatively high. After amplification by components 339, 324, and 324, this provides sufficient voltage to relay J1 or J2, causing the relay to engage. When either of the two starters starts, that is, when KM1 or KM2 closes, the main circuit is connected through a capacitor, causing the oscillator to stop working, the relay to stop working, and the leakage current lockout circuit to be disconnected.

[0027] Because the two circuit boards are connected in parallel in the circuit, as long as one starter is engaged, both oscillation circuits will stop working, ensuring the normal operation of the starters. Even if one starter is not powered, the corresponding relay will not be engaged, and the leakage current interlocking circuit will not be connected, so it will not affect the operation of the other starter. More importantly, this function can be implemented without wiring between the starters; only a normally open contact of a relay J1 or J2 needs to be connected inside starter I or II, which greatly simplifies the operation.

[0028] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A coal mine explosion-proof vacuum starter leakage lock parallel operation device, characterized in that: comprising a starter I and a starter II arranged in parallel, a circuit board I and a circuit board II are additionally arranged in the starter I and the starter II respectively, and the circuit board I and the circuit board II are connected in parallel in a three-phase power grid; the circuit board I and the circuit board II are provided with self-oscillators, wherein the carrier frequency signal generated by the self-oscillator on the circuit board I is output through two paths, one of which is coupled with the three-phase power grid after processing, and the other is amplified to control the relay J1 on the circuit board I to be attracted; the carrier frequency signal generated by the self-oscillator on the circuit board II is output through two paths, one of which is coupled with the three-phase power grid after processing, and the other is amplified to control the relay J2 on the circuit board II to be attracted; the normally open contact of the relay J1 is connected in series with the leakage protection circuit of the starter I, and the normally open contact of the relay J2 is connected in series with the leakage protection circuit of the starter II; the series circuit I composed of the normally open contact KM1 of the vacuum contactor of the starter I and a capacitor, and the series circuit II composed of the normally open contact KM2 of the vacuum contactor of the starter II and a capacitor are connected in the three-phase power grid.

2. The coal mine explosion-proof vacuum starter leakage lock parallel operation device according to claim 1, characterized in that: the self-oscillator comprises a triode BG, an inductor L1, capacitors C5 and C6, and a resistor R2, the self-oscillator is provided with stable voltage by a voltage stabilizing circuit of the three-phase power grid, the self-oscillator is a three-point self-oscillator, and is used to generate a carrier frequency signal of 20KHz, and when the isolation commutating switch of the starter is powered, the corresponding self-oscillator generates a carrier frequency signal.

3. The parallel operation device of the coal mine explosion-proof vacuum starter leakage lockout according to claim 1, characterized in that: one of the carrier frequency signals is coupled with the three-phase power grid of 660V / 1140V through a circuit composed of an inductor L2, resistors R3 and R4, and capacitors C7 and C8.

4. The parallel operation device of the coal mine explosion-proof vacuum starter leakage lockout according to claim 1, characterized in that: the other carrier frequency signal is amplified by three groups of amplifying elements and then output to the corresponding relay J1 or relay J2.

5. The parallel operation device of the coal mine explosion-proof vacuum starter leakage lockout according to claim 1, characterized in that: the series circuit I composed of the normally open contact KM1 of the vacuum contactor of the starter I and a capacitor, and the series circuit II composed of the normally open contact KM2 of the vacuum contactor of the starter II and a capacitor are used to short the oscillation circuit where the self-oscillator is located, so as to disconnect the relay J1 and the relay J2, and then cut off the leakage lock protection circuit of the starter I and the starter II.

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