Switch cabinet partial discharge detection circuit

Abstract

The invention discloses a partial discharge detection circuit for a switch cabinet, and relates to the field of current detection, and the circuit comprises a discharge detection module which is used for detecting ground electric waves generated by partial discharge of the switch cabinet, converting the ground electric waves into stable voltage through a first capacitor, obtaining a detection signal, and outputting the detection signal to an isolation feedback module; compared with the prior art, the method has the advantages that whether partial discharge exists in the switch cabinet or not is detected through ground waves, detection can be conducted when the switch cabinet is in an electrified state, and limitation is small; a ground electric wave which is difficult to judge is changed into a stable voltage signal through the discharge detection module (the first capacitor), and the discharge grade of partial discharge of the switch cabinet can be judged through the discharge digital indication module and the discharge size indication module; the pressure relief control module and the delay driving module are matched to ensure that the discharge detection module can be subjected to pressure relief in time, the circuit is prevented from being damaged, and meanwhile, whether related modules fail or not can be detected according to whether a light-emitting tube emits light or not.

Description

Technical Field

[0001] The invention relates to the field of current detection, in particular to a partial discharge detection circuit for a switch cabinet. Background Art

[0002] Partial discharge of switchgear refers to electrical discharge caused by breakdown of the insulation part of the switchgear. It can occur near the conductor or in other areas. Conventional non-voltage and voltage withstand tests are difficult to detect insulation defects such as partial discharge. Partial discharge will lead to a vicious cycle of insulation degradation and defects in power equipment, and even lead to insulation accidents in severe cases. Therefore, it is necessary to detect partial discharge to avoid sudden insulation damage accidents in power equipment during operation.

[0003] The existing pulse current detection method for detecting partial discharge of switch cabinets is generally used when the switch cabinet is powered off, and cannot be used when the switch cabinet is powered normally. It has great limitations and needs to be improved. Summary of the invention

[0004] The object of the present invention is to provide a partial discharge detection circuit for a switch cabinet to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A switch cabinet partial discharge detection circuit, comprising:

[0007] The discharge detection module is used to detect the ground wave generated by the partial discharge of the switch cabinet, convert it into a stable voltage through the first capacitor, obtain a detection signal, and output it to the isolation feedback module; the stronger the ground wave (the greater the partial discharge intensity of the switch cabinet), the longer the discharge detection module takes to output the detection signal to the isolation feedback module;

[0008] The isolation feedback module is used to charge the second capacitor when receiving the detection signal, and the voltage on the second capacitor is different based on the different charging time of the second capacitor; based on the voltage on the second capacitor, whether to drive the alarm module and the discharge size indication module;

[0009] Alarm module, used to alarm and prompt partial discharge of switch cabinet during operation;

[0010] The discharge size indication module is used to display the local discharge intensity of the switch cabinet by whether the light-emitting tube emits light during operation;

[0011] A discharge digital indication module, used to detect the voltage on the second capacitor;

[0012] A pressure relief control module is used to work when all the light-emitting tubes of the discharge size indication module are lit, and control the pressure relief working module to work;

[0013] The delay driving module is used to directly drive the pressure relief control module to work when the working time of the alarm module reaches the set value;

[0014] A pressure relief working module, used for controlling the first capacitor to be grounded for pressure relief during operation;

[0015] The output end of the discharge detection module is connected to the input end of the isolation feedback module, the output end of the isolation feedback module is connected to the input end of the alarm module, the input end of the discharge size indication module, and the input end of the discharge digital indication module, the output end of the discharge size indication module is connected to the first input end of the pressure relief control module, the output end of the alarm module is connected to the input end of the delay drive module, the output end of the delay drive module is connected to the second input end of the pressure relief control module, the output end of the pressure relief control module is connected to the input end of the pressure relief working module, and the output end of the pressure relief working module is connected to the input end of the discharge detection module.

[0016] As a further solution of the present invention: the discharge detection module includes a detection head, a first resistor, a second resistor, a first transistor, a second transistor, a first diode, a first capacitor, and a second diode. The detection head is connected to the base of the first transistor, the collector of the first transistor is connected to one end of the first resistor, the other end of the first resistor is connected to the power supply voltage, the emitter of the first transistor is connected to the base of the second transistor, the collector of the second transistor is connected to one end of the second resistor, the other end of the second resistor is connected to the power supply voltage, the emitter of the second transistor is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the first capacitor, the positive electrode of the second diode, and the output end of the pressure relief working module, the other end of the first capacitor is grounded, and the negative electrode of the second diode is connected to the input end of the isolation feedback module.

[0017] As a further solution of the present invention: the isolation feedback module includes a third resistor, an optocoupler, a fourth resistor, a fifth resistor, a third MOS tube, a seventh resistor, and a second capacitor. One end of the third resistor is connected to the output end of the discharge detection module, one end of the third resistor is connected to the first end of the optocoupler, the second end of the optocoupler is grounded, the third end of the optocoupler is connected to one end of the fourth resistor and the G pole of the third MOS tube, the fourth end of the optocoupler is grounded, the other end of the fourth resistor is connected to the power supply voltage, the S pole of the third MOS tube is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the power supply voltage, the D pole of the third MOS tube is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the second capacitor, the input end of the alarm module, the input end of the discharge size indication module, and the input end of the discharge digital indication module, and the other end of the second capacitor is grounded.

[0018] As a further solution of the present invention: the alarm module includes a sixth resistor, a buzzer, a fourth transistor, and a third diode, one end of the sixth resistor is connected to the power supply voltage, the other end of the sixth resistor is connected to one end of the buzzer, the other end of the buzzer is connected to the collector of the fourth transistor, the emitter of the fourth transistor is connected to the anode of the third diode, the cathode of the third diode is grounded, the base of the fourth transistor is connected to the output end of the isolation feedback module, and the third diode is a light emitting diode.

[0019] As a further solution of the present invention: the discharge size indication module includes a plurality of discharge size indication units, and the plurality of discharge size indication units are connected in parallel.

[0020] As a further solution of the present invention: the discharge size indication unit includes a fourth diode, an eighth resistor, a first voltage-stabilizing diode, and a seventh diode. The positive electrode of the fourth diode is connected to the output end of the isolation feedback module, the negative electrode of the fourth diode is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to the negative electrode of the first voltage-stabilizing diode, the positive electrode of the first voltage-stabilizing diode is connected to the positive electrode of the seventh diode, and the negative electrode of the seventh diode is grounded. The rated voltages of the voltage-stabilizing diodes of different discharge size indication units are different, and the seventh diode is a light-emitting diode.

[0021] As a further solution of the present invention: the discharge digital indication module includes a tenth diode and a voltmeter, the anode of the tenth diode is connected to the output end of the isolation feedback module, the cathode of the tenth diode is connected to one end of the voltmeter, and the other end of the voltmeter is grounded.

[0022] As a further solution of the present invention: the pressure relief control module includes an eleventh resistor, a first relay, an eleventh diode, and a plurality of transistors, wherein the transistors are photosensitive transistors, the number of the transistors corresponds to the discharge size indication unit, the base of each transistor only receives the light of the light-emitting diode corresponding to the discharge size indication unit, and the emitter of the previous transistor is connected to the collector of the next transistor;

[0023] One end of the eleventh resistor is connected to the power supply voltage, the other end of the eleventh resistor is connected to one end of the first relay and the cathode of the eleventh diode, the other end of the first relay is connected to the anode of the eleventh diode, the output end of the delay drive module, the collector of the first transistor, and the emitter of the last transistor is grounded.

[0024] As a further solution of the present invention: the delay driving module includes a twelfth resistor, a ninth transistor, a thirteenth resistor, a third capacitor, an eighth MOS tube, and a twelfth diode, one end of the twelfth resistor is connected to the power supply voltage, the other end of the twelfth resistor is connected to the collector of the ninth transistor, the ninth transistor is a photosensitive transistor, the base of the ninth transistor only receives light from the third diode, the emitter of the ninth transistor is connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is connected to one end of the third capacitor and the G pole of the eighth MOS tube, the other end of the third capacitor is grounded, the D pole of the eighth MOS tube is connected to the second input end of the pressure relief control module, the S pole of the eighth MOS tube is connected to the positive pole of the twelfth diode, the negative pole of the twelfth diode is grounded, and the twelfth diode is a light-emitting diode.

[0025] As a further solution of the present invention: the pressure relief working module includes a first switch and a second switch, one end of the first switch is connected to one end of the second switch and an input end of the discharge detection module, the other end of the first switch is grounded, and the other end of the second switch is grounded.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention detects whether there is partial discharge in the switch cabinet through ground waves, and the switch cabinet can be detected when it is in a energized state, with less restrictions; the ground waves that are difficult to determine are converted into stable voltage signals through the discharge detection module (first capacitor), and the discharge level of the partial discharge of the switch cabinet can be judged through the discharge digital indication module and the discharge size indication module; the provided pressure relief control module and the delay drive module cooperate to ensure that the pressure can be relieved to the discharge detection module in time to avoid damage to the circuit, and at the same time, whether the related module is faulty can be detected by whether the light-emitting tube emits light. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a schematic diagram of a partial discharge detection circuit for a switch cabinet.

[0028] Figure 2 This is a schematic diagram of the discharge size indication module.

[0029] Figure 3 It is the circuit diagram of the discharge detection module, isolation feedback module and alarm module.

[0030] Figure 4 This is the circuit diagram of the discharge size indication module.

[0031] Figure 5 This is the circuit diagram of the discharge digital indication module.

[0032] Figure 6 It is the circuit diagram of the pressure relief control module and the delay drive module.

[0033] Figure 7 This is the circuit diagram of the pressure relief working module. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of 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.

[0035] See also Figure 1 , a switch cabinet partial discharge detection circuit, comprising:

[0036] The discharge detection module 1 is used to detect the ground wave generated by the partial discharge of the switch cabinet, convert it into a stable voltage through the first capacitor C1, obtain a detection signal, and output it to the isolation feedback module 2; the stronger the ground wave (the greater the partial discharge intensity of the switch cabinet), the longer the discharge detection module 1 outputs the detection signal to the isolation feedback module 2;

[0037] The isolation feedback module 2 is used to charge the second capacitor C2 when receiving the detection signal. The voltage on the second capacitor C2 varies depending on the charging time of the second capacitor C2. The alarm module 3 and the discharge size indication module 4 are selected based on the voltage on the second capacitor C2.

[0038] Alarm module 3, used to alarm and prompt partial discharge of the switch cabinet during operation;

[0039] The discharge magnitude indication module 4 is used to display the magnitude of the local discharge intensity of the switch cabinet by indicating whether the light-emitting tube emits light during operation;

[0040] A discharge digital indication module 5 is used to detect the voltage on the second capacitor C2;

[0041] The pressure relief control module 6 is used to work when all the light-emitting tubes of the discharge size indication module 4 are emitting light, and control the pressure relief working module 8 to work;

[0042] The time-delay driving module 7 is used to directly drive the pressure relief control module 6 to work when the working time of the alarm module 3 reaches a set value;

[0043] A pressure relief working module 8, used for controlling the first capacitor C1 to be grounded for pressure relief during operation;

[0044] The output end of the discharge detection module 1 is connected to the input end of the isolation feedback module 2, the output end of the isolation feedback module 2 is connected to the input end of the alarm module 3, the input end of the discharge size indication module 4, and the input end of the discharge digital indication module 5, the output end of the discharge size indication module 4 is connected to the first input end of the pressure relief control module 6, the output end of the alarm module 3 is connected to the input end of the delay drive module 7, the output end of the delay drive module 7 is connected to the second input end of the pressure relief control module 6, the output end of the pressure relief control module 6 is connected to the input end of the pressure relief working module 8, and the output end of the pressure relief working module 8 is connected to the input end of the discharge detection module 1.

[0045] In a specific embodiment: When partial discharge occurs in the insulation layer of the switch cabinet, electromagnetic waves will be generated. Since the metal shell of the switch cabinet has a shielding effect, most of the electromagnetic waves will be blocked, but a small amount of electromagnetic waves will still propagate through the joints of the metal shell or the gas-insulated switch liner, and generate a ground wave that passes through the outer surface of the metal shell of the equipment to the ground. The range of this ground wave is usually between a few millivolts and a few volts, and the rise time is extremely short. Therefore, the ground wave can be used to detect whether there is partial discharge in the switch cabinet.

[0046] In this example: See Figure 3 The discharge detection module 1 includes a detection head X, a first resistor R1, a second resistor R2, a first triode V1, a second triode V2, a first diode D1, a first capacitor C1, and a second diode D2. The detection head X is connected to the base of the first triode V1, the collector of the first triode V1 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the power supply voltage VCC, the emitter of the first triode V1 is connected to the base of the second triode V2, the collector of the second triode V2 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the power supply voltage VCC, the emitter of the second triode V2 is connected to the positive electrode of the first diode D1, the negative electrode of the first diode D1 is connected to one end of the first capacitor C1, the positive electrode of the second diode D2, and the output end of the pressure relief working module 8, the other end of the first capacitor C1 is grounded, and the negative electrode of the second diode D2 is connected to the input end of the isolation feedback module 2.

[0047] Since the range of ground wave is usually between several millivolts and several volts, and the rise time is extremely short, it is necessary to convert it into a measurable voltage signal. Therefore, a discharge detection module 1 is designed. The detection head X is placed on the metal panel on the surface of the switch cabinet. The ground wave is introduced through the detection head X. Since the ground wave has several millivolts, the first transistor V1 and the second transistor V2 are designed to perform two-stage amplification to amplify the ground wave signal. After passing through the first diode D1, it is stored in the first capacitor C1. The first capacitor C1 stores the electric energy of the amplified ground wave and outputs it through the second diode D2. The stronger the ground wave, the longer the time for the first capacitor C1 to output the voltage through the second diode D2. The weaker the ground wave, the shorter the time for the first capacitor C1 to output the voltage through the second diode D2, so that the strength of the ground wave can be measured.

[0048] In another embodiment, two triodes are used to amplify the ground wave signal, and the ground wave signal can also be amplified by an amplifier or other device.

[0049] In this example: See Figure 3 The isolation feedback module 2 includes a third resistor R3, an optocoupler U1, a fourth resistor R4, a fifth resistor R5, a third MOS tube V3, a seventh resistor R7, and a second capacitor C2. One end of the third resistor R3 is connected to the output end of the discharge detection module 1, one end of the third resistor R3 is connected to the first end of the optocoupler U1, the second end of the optocoupler U1 is grounded, the third end of the optocoupler U1 is connected to one end of the fourth resistor R4 and the G pole of the third MOS tube V3, the fourth end of the optocoupler U1 is grounded, the other end of the fourth resistor R4 is connected to the power supply voltage VCC, the S pole of the third MOS tube V3 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the power supply voltage VCC, the D pole of the third MOS tube V3 is connected to one end of the seventh resistor R7, the other end of the seventh resistor R7 is connected to one end of the second capacitor C2, the input end of the alarm module 3, the input end of the discharge size indication module 4, and the input end of the discharge digital indication module 5, and the other end of the second capacitor C2 is grounded.

[0050] When the first capacitor C1 outputs a voltage through the second diode D2, it passes through the third resistor R3, so that the light-emitting diode inside the optocoupler U1 emits light, and the photosensitive transistor inside the optocoupler U1 is turned on, so that the G pole of the third MOS tube V3 (PMOS) changes from a high level to a low level, and the third MOS tube V3 is turned on. The power supply voltage VCC charges the second capacitor C2 through the fifth resistor R5, the third MOS tube V3, and the seventh resistor R7. The stronger the ground wave, the longer the charging time of the second capacitor C2, and the greater the voltage on the second capacitor C2. Therefore, the voltage on the second capacitor C2 reflects the strength of the ground wave.

[0051] In another embodiment, the optocoupler U1 may be omitted. The optocoupler U1 is provided for isolation, and the output signal will not affect the input signal, thereby ensuring the stability and independence of the signal.

[0052] In this example: See Figure 3 The alarm module 3 includes a sixth resistor R6, a buzzer BUZZ, a fourth transistor V4, and a third diode D3. One end of the sixth resistor R6 is connected to the power supply voltage VCC, the other end of the sixth resistor R6 is connected to one end of the buzzer BUZZ, the other end of the buzzer BUZZ is connected to the collector of the fourth transistor V4, the emitter of the fourth transistor V4 is connected to the anode of the third diode D3, the cathode of the third diode D3 is grounded, the base of the fourth transistor V4 is connected to the output end of the isolation feedback module 2, and the third diode D3 is a light emitting diode.

[0053] When the voltage on the second capacitor C2 is sufficient to turn on the fourth transistor V4, it indicates that partial discharge exists in the current switch cabinet. After the fourth transistor V4 is turned on, the buzzer BUZZ sounds for prompting, and the third diode D3 lights up for indication.

[0054] In another embodiment, the BUZZ buzzer can be replaced by a voice prompt device such as a voice chip.

[0055] In this example: See Figure 2 and Figure 4 The discharge size indication module 4 includes a plurality of discharge size indication units 41, and the plurality of discharge size indication units 41 are connected in parallel.

[0056] In this example: See Figure 4 The discharge size indicating unit 41 includes a fourth diode D4, an eighth resistor R8, a first voltage stabilizing diode Z1, and a seventh diode D7. The anode of the fourth diode D4 is connected to the output end of the isolation feedback module 2, the cathode of the fourth diode D4 is connected to one end of the eighth resistor R8, the other end of the eighth resistor R8 is connected to the cathode of the first voltage stabilizing diode Z1, the anode of the first voltage stabilizing diode Z1 is connected to the anode of the seventh diode D7, and the cathode of the seventh diode D7 is grounded. The rated voltages of the voltage stabilizing diodes of different discharge size indicating units 41 are different, and the seventh diode D7 is a light emitting diode.

[0057] In order to clearly indicate the magnitude of the ground wave (the intensity of the partial discharge of the switch cabinet), a discharge magnitude indication module 4 is provided. The discharge magnitude indication module 4 is provided with a plurality of discharge magnitude indication units 41. Figure 2 , Figure 4There are three discharge size indicating units 41, and here the three discharge size indicating units 41 are used as examples. It should be noted that the second capacitor C2 is directly connected to the base of the fourth transistor V4, so the alarm module 3 works before the discharge size indicating unit 41.

[0058] As the charging progresses, the voltage of the second capacitor C2 gradually rises, and the voltage of the common point A1 rises. The rated voltage of the first voltage zener diode Z1 is less than the rated voltage of the second voltage zener diode Z2 and less than the rated voltage of the third voltage zener diode Z3. Therefore, the first voltage zener diode Z1 will be turned on first, and as the charging progresses, the second voltage zener diode Z2 will be turned on. As the charging progresses further, the third voltage zener diode Z3 will also be turned on. After the voltage zener diode is turned on, its series-connected light-emitting diodes (the seventh diode D7, the eighth diode D8, and the ninth diode D9) will also emit light. Therefore, by observing the number of light-emitting diodes, the size of the current ground wave can be determined.

[0059] In another embodiment, three discharge size indicating units 41 are used as an example, and the number of the discharge size indicating units 41 is not limited in actual use.

[0060] In this example: See Figure 5 The discharge digital indication module 5 includes a tenth diode D10 and a voltmeter V, wherein the anode of the tenth diode D10 is connected to the output end of the isolation feedback module 2, the cathode of the tenth diode D10 is connected to one end of the voltmeter V, and the other end of the voltmeter V is grounded.

[0061] Also, in order to clearly indicate the magnitude of the ground wave (the intensity of the partial discharge of the switch cabinet), a discharge digital indication module 5 is provided, and the magnitude of the ground wave can be observed through the pointer reading of the voltmeter V.

[0062] In another embodiment: the common point A1 can also be connected to a single-chip microcomputer, and the single-chip microcomputer is connected to a display screen. After the voltage signal of the common point A1 is processed by the single-chip microcomputer, specific numbers are displayed on the display screen to show the size of the ground wave, thereby replacing the voltmeter V.

[0063] In this example: See Figure 6 The pressure relief control module 6 includes an eleventh resistor R11, a first relay J1, an eleventh diode D11, and a plurality of transistors, wherein the transistors are photosensitive transistors, and the number of the transistors corresponds to the discharge size indication unit 41. The base of each transistor only receives the light of the light-emitting diode corresponding to the discharge size indication unit 41 (not affected by other light-emitting diodes), and the emitter of the previous transistor is connected to the collector of the next transistor;

[0064] One end of the eleventh resistor R11 is connected to the power supply voltage VCC, the other end of the eleventh resistor R11 is connected to one end of the first relay J1 and the cathode of the eleventh diode D11, the other end of the first relay J1 is connected to the anode of the eleventh diode D11, the output end of the delay driving module 7, the collector of the first transistor, and the emitter of the last transistor is grounded.

[0065] The range of ground waves is usually between a few millivolts and a few volts, and the rise time is extremely short. Therefore, the first transistor V1 and the second transistor V2 are designed for two-stage discharge to ensure that the voltage on the first capacitor C1 is sufficient to drive the optocoupler U1 to work when the ground wave is a few millivolts. However, when the ground wave is large (several volts), in order to ensure the collection of the ground wave, the first capacitor C1 only has a third resistor R3 set on the output side. When the voltage is continuously input, the electric energy cannot be consumed in time, and there is a possibility that the voltage on the first capacitor C1 accumulates to a large extent, destroying the circuit.

[0066] Still taking the three discharge size indicating units 41 as an example, when the first capacitor C1 continuously drives the optocoupler U1, so that the voltage of the second capacitor C2 continues to rise, causing the seventh diode D7, the eighth diode D8, and the ninth diode D9 to all emit light (it is determined that the voltage accumulation on the first capacitor C1 is large), the corresponding phototransistors (the fifth transistor V5, the sixth transistor V6, and the seventh transistor V7, respectively) are all turned on. When the light-emitting diodes of all the discharge size indicating units 41 are all lit, all the phototransistors of the pressure relief control module 6 are also turned on, the first relay J1 is energized to work, and the pressure relief working module 8 is controlled to work, so as to discharge the voltage on the first capacitor C1, so as to prevent the voltage accumulation of the first capacitor C1 from damaging the circuit.

[0067] In another embodiment: the power supply voltage VCC is a stable voltage, which can be obtained through a device such as a voltage stabilizer.

[0068] In this example: See Figure 6The delay driving module 7 includes a twelfth resistor R12, a ninth transistor V9, a thirteenth resistor R13, a third capacitor C3, an eighth MOS transistor V8, and a twelfth diode D12. One end of the twelfth resistor R12 is connected to the power supply voltage VCC, and the other end of the twelfth resistor R12 is connected to the collector of the ninth transistor V9. The ninth transistor V9 is a photosensitive transistor. The base of the ninth transistor V9 only receives the light of the third diode D3 (not affected by other light-emitting diodes). The emitter of the ninth transistor V9 is connected to one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is connected to one end of the third capacitor C3 and the G pole of the eighth MOS transistor V8. The other end of the third capacitor C3 is grounded, the D pole of the eighth MOS transistor V8 is connected to the second input end of the pressure relief control module 6, the S pole of the eighth MOS transistor V8 is connected to the positive pole of the twelfth diode D12, the negative pole of the twelfth diode D12 is grounded, and the twelfth diode D12 is a light-emitting diode.

[0069] Under normal conditions, when the accumulated voltage on the first capacitor C1 is too large, all the light-emitting diodes of the discharge size indication unit 41 are illuminated, all the phototransistors of the pressure relief control module 6 are also turned on, and the first relay J1 is energized to work to relieve the pressure on the first capacitor C1. However, there is a possibility of failure of the discharge size indication unit 41 and failure of the phototransistor of the pressure relief control module 6. At this time, the voltage on the first capacitor C1 accumulates, and there is a possibility of damaging the circuit. Therefore, a delay drive module 7 is set.

[0070] When the alarm module 3 is working, the third diode D3 emits light, so that the ninth transistor V9 is turned on, and the third capacitor C3 is charged. When the accumulated voltage on the first capacitor C1 is too large; under normal conditions (the light-emitting diodes of the discharge size indication unit 41 are all illuminated, and all the photosensitive transistors of the pressure relief control module 6 are also turned on), the first capacitor C1 discharges the voltage after the first relay J1 works, and when the alarm module 3 does not work, the voltage on the third capacitor C3 is also gradually consumed; under abnormal conditions (when at least one of the discharge size indication unit 41 fails and the photosensitive transistor of the pressure relief control module 6 fails), the third capacitor C3 continues to charge. When it is charged to a level sufficient to turn on the eighth MOS tube V8 (NMOS), the first relay J1 forms a loop through the eighth MOS tube V8 and the twelfth diode D12, and the first relay J1 is energized to work, and the pressure relief working module 8 is controlled to discharge the pressure on the first capacitor C1, thereby playing a protective role.

[0071] In another embodiment: the twelfth diode D12 can be omitted, where the twelfth diode D12, the third diode D3, the seventh diode D7, the eighth diode D8, and the ninth diode D9 serve as indicators for each other, facilitating the determination of whether the circuit has a fault;

[0072] When the accumulated voltage on the first capacitor C1 is normal, the third diode D3 emits light, and at most the seventh diode D7 and the eighth diode D8 among the seventh diode D7, the eighth diode D8 and the ninth diode D9 emit light;

[0073] When the accumulated voltage on the first capacitor C1 is too large and the first capacitor C1 is working normally, the third diode D3 emits light, and the seventh diode D7, the eighth diode D8, and the ninth diode D9 all emit light;

[0074] When the accumulated voltage on the first capacitor C1 is too large and works abnormally, the third diode D3 emits light, the seventh diode D7, the eighth diode D8, and the ninth diode D9 do not all emit light, and the twelfth diode D12 emits light, which can indicate that the discharge size indication unit 41 is faulty;

[0075] When the accumulated voltage on the first capacitor C1 is too large and works abnormally, the third diode D3 emits light, the seventh diode D7, the eighth diode D8, and the ninth diode D9 all emit light, and the twelfth diode D12 emits light, which can indicate that the phototransistor of the pressure relief control module 6 is faulty;

[0076] The third diode D3 does not emit light, while the seventh diode D7, the eighth diode D8, and the ninth diode D9 emit light, indicating that the alarm module 3 is faulty. The alarm module 3 can be processed in time to avoid the inability to drive the delay drive module 7 to work for protection when at least one of the photosensitive transistors of the discharge size indication unit 41 and the pressure relief control module 6 fails.

[0077] In this example: See Figure 7 The pressure relief working module 8 includes a first switch S1 and a second switch S2. One end of the first switch S1 is connected to one end of the second switch S2 and the input end of the discharge detection module 1. The other end of the first switch S1 is grounded, and the other end of the second switch S2 is grounded.

[0078] When the first relay J1 is working, the first switch S1 is closed, the common point A2 is grounded, and the first capacitor C1 quickly discharges electricity to prevent voltage accumulation from damaging the circuit. The second switch S2 is a manual switch, and the user manually controls the protection circuit.

[0079] In another embodiment: the first capacitor C1 is automatically discharged by controlling the first switch S1 to be closed by the first relay J1, or the first capacitor C1 can be controlled to discharge electricity by controlling a switch tube (transistor, MOS tube, IGBT tube, etc.) through an electrical signal.

[0080] The working principle of the present invention is: the discharge detection module 1 is used to detect the ground wave generated by the partial discharge of the switch cabinet, and converts it into a stable voltage through the first capacitor C1 to obtain a detection signal, which is output to the isolation feedback module 2; the stronger the ground wave (the greater the local discharge intensity of the switch cabinet), the longer the time for the discharge detection module 1 to output the detection signal to the isolation feedback module 2; the isolation feedback module 2 is used to charge the second capacitor C2 when receiving the detection signal, and the voltage on the second capacitor C2 is different based on the different charging time of the second capacitor C2; based on the voltage on the second capacitor C2, it is selected whether to drive the alarm module 3, discharge Size indication module 4; alarm module 3 is used to alarm and prompt partial discharge of switch cabinet during operation; discharge size indication module 4 is used to display the size of partial discharge intensity of switch cabinet by whether the light-emitting tube is emitting light during operation; discharge digital indication module 5 is used to detect the voltage size on the second capacitor C2; pressure relief control module 6 is used to work when all the light-emitting tubes of discharge size indication module 4 are emitting light, and control the pressure relief working module 8 to work; delay drive module 7 is used to directly drive the pressure relief control module 6 to work when the working time of alarm module 3 reaches the set value; pressure relief working module 8 is used to control the first capacitor C1 to be grounded for pressure relief during operation.

[0081] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered as exemplary and non-restrictive in all respects.

[0082] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A switch cabinet partial discharge detection circuit, characterized in that: The switch cabinet partial discharge detection circuit includes: The discharge detection module is used to detect the ground wave generated by the partial discharge of the switch cabinet, convert it into a stable voltage through the first capacitor, obtain a detection signal, and output it to the isolation feedback module; the stronger the ground wave, the longer the time it takes for the discharge detection module to output the detection signal to the isolation feedback module; The isolation feedback module is used to charge the second capacitor when receiving the detection signal, and the voltage on the second capacitor is different based on the different charging time of the second capacitor; based on the voltage on the second capacitor, whether to drive the alarm module and the discharge size indication module; Alarm module, used to alarm and prompt partial discharge of switch cabinet during operation; The discharge size indication module is used to display the local discharge intensity of the switch cabinet by whether the light-emitting tube emits light during operation; A discharge digital indication module, used to detect the voltage on the second capacitor; A pressure relief control module is used to work when all the light-emitting tubes of the discharge size indication module are lit, and control the pressure relief working module to work; The delay driving module is used to directly drive the pressure relief control module to work when the working time of the alarm module reaches the set value; A pressure relief working module, used for controlling the first capacitor to be grounded for pressure relief during operation; The output end of the discharge detection module is connected to the input end of the isolation feedback module, the output end of the isolation feedback module is connected to the input end of the alarm module, the input end of the discharge size indication module, and the input end of the discharge digital indication module, the output end of the discharge size indication module is connected to the first input end of the pressure relief control module, the output end of the alarm module is connected to the input end of the delay drive module, the output end of the delay drive module is connected to the second input end of the pressure relief control module, the output end of the pressure relief control module is connected to the input end of the pressure relief working module, and the output end of the pressure relief working module is connected to the input end of the discharge detection module.

2. The switch cabinet partial discharge detection circuit according to claim 1, characterized in that: The discharge detection module includes a detection head, a first resistor, a second resistor, a first triode, a second triode, a first diode, a first capacitor, and a second diode. The detection head is connected to the base of the first triode, the collector of the first triode is connected to one end of the first resistor, the other end of the first resistor is connected to the power supply voltage, the emitter of the first triode is connected to the base of the second triode, the collector of the second triode is connected to one end of the second resistor, the other end of the second resistor is connected to the power supply voltage, the emitter of the second triode is connected to the positive electrode of the first diode, the negative electrode of the first diode is connected to one end of the first capacitor, the positive electrode of the second diode, and the output end of the pressure relief working module, the other end of the first capacitor is grounded, and the negative electrode of the second diode is connected to the input end of the isolation feedback module.

3. The switch cabinet partial discharge detection circuit according to claim 1, characterized in that: The isolation feedback module includes a third resistor, an optocoupler, a fourth resistor, a fifth resistor, a third MOS tube, a seventh resistor, and a second capacitor. One end of the third resistor is connected to the output end of the discharge detection module, one end of the third resistor is connected to the first end of the optocoupler, the second end of the optocoupler is grounded, the third end of the optocoupler is connected to one end of the fourth resistor and the G pole of the third MOS tube, the fourth end of the optocoupler is grounded, the other end of the fourth resistor is connected to the power supply voltage, the S pole of the third MOS tube is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the power supply voltage, the D pole of the third MOS tube is connected to one end of the seventh resistor, the other end of the seventh resistor is connected to one end of the second capacitor, the input end of the alarm module, the input end of the discharge size indication module, and the input end of the discharge digital indication module, and the other end of the second capacitor is grounded.

4. The switch cabinet partial discharge detection circuit according to claim 1, characterized in that: The alarm module includes a sixth resistor, a buzzer, a fourth transistor, and a third diode. One end of the sixth resistor is connected to the power supply voltage, the other end of the sixth resistor is connected to one end of the buzzer, the other end of the buzzer is connected to the collector of the fourth transistor, the emitter of the fourth transistor is connected to the anode of the third diode, the cathode of the third diode is grounded, the base of the fourth transistor is connected to the output end of the isolation feedback module, and the third diode is a light-emitting diode.

5. The switch cabinet partial discharge detection circuit according to any one of claims 1 to 4, characterized in that: The discharge size indication module includes a plurality of discharge size indication units, and the plurality of discharge size indication units are connected in parallel.

6. The switch cabinet partial discharge detection circuit according to claim 5, characterized in that: The discharge size indication unit includes a fourth diode, an eighth resistor, a first voltage-stabilizing diode, and a seventh diode. The anode of the fourth diode is connected to the output end of the isolation feedback module, the cathode of the fourth diode is connected to one end of the eighth resistor, the other end of the eighth resistor is connected to the cathode of the first voltage-stabilizing diode, the anode of the first voltage-stabilizing diode is connected to the anode of the seventh diode, and the cathode of the seventh diode is grounded. The rated voltages of the voltage-stabilizing diodes of different discharge size indication units are different, and the seventh diode is a light-emitting diode.

7. The switch cabinet partial discharge detection circuit according to claim 1, characterized in that: The discharge digital indication module comprises a tenth diode and a voltmeter, wherein the anode of the tenth diode is connected to the output end of the isolation feedback module, the cathode of the tenth diode is connected to one end of the voltmeter, and the other end of the voltmeter is grounded.

8. The switch cabinet partial discharge detection circuit according to claim 6, characterized in that: The pressure relief control module includes an eleventh resistor, a first relay, an eleventh diode, and a plurality of transistors, wherein the transistors are photosensitive transistors, the number of the transistors corresponds to the discharge size indication unit, the base of each transistor only receives the light of the light-emitting diode of the corresponding discharge size indication unit, and the emitter of the previous transistor is connected to the collector of the next transistor; One end of the eleventh resistor is connected to the power supply voltage, the other end of the eleventh resistor is connected to one end of the first relay and the cathode of the eleventh diode, the other end of the first relay is connected to the anode of the eleventh diode, the output end of the delay drive module, the collector of the first transistor, and the emitter of the last transistor is grounded.

9. The switch cabinet partial discharge detection circuit according to claim 4, characterized in that: The delay driving module includes a twelfth resistor, a ninth transistor, a thirteenth resistor, a third capacitor, an eighth MOS tube, and a twelfth diode. One end of the twelfth resistor is connected to the power supply voltage, the other end of the twelfth resistor is connected to the collector of the ninth transistor, the ninth transistor is a photosensitive transistor, the base of the ninth transistor only receives light from the third diode, the emitter of the ninth transistor is connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is connected to one end of the third capacitor and the G pole of the eighth MOS tube, the other end of the third capacitor is grounded, the D pole of the eighth MOS tube is connected to the second input end of the pressure relief control module, the S pole of the eighth MOS tube is connected to the positive pole of the twelfth diode, the negative pole of the twelfth diode is grounded, and the twelfth diode is a light-emitting diode.

10. The switch cabinet partial discharge detection circuit according to claim 1, characterized in that: The pressure relief working module includes a first switch and a second switch, one end of the first switch is connected to one end of the second switch and the input end of the discharge detection module, the other end of the first switch is grounded, and the other end of the second switch is grounded.

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