Load access protection circuit and insulation test equipment

Abstract

The utility model provides a load access protection circuit and insulation test equipment, which belongs to the technical field of insulation test and comprises an access module, a comparison module and a protection module. One end of the access module is connected with a signal end, the other end of the access module is connected with the input end of the comparison module, the output end of the comparison module is connected with the protection module, and the protection module is further connected with the access module; the access module is used for accessing a load and setting an overvoltage protection threshold value, the comparison module is used for comparing a real-time voltage with the overvoltage protection threshold value and outputting a level signal, and the protection module is used for giving an alarm based on the level signal and disconnecting the access of the load. And overvoltage protection is effectively carried out.

Description

Technical Field

[0001] The utility model relates to the technical field of insulation testing, in particular to a load access protection circuit and an insulation testing device. Background Technique

[0002] During the application of new energy products, it is often necessary to test and verify the insulation function of the high-voltage system. At this time, a specific resistance value needs to be given to check whether the resistance value reported from the product measurement meets the requirements such as accuracy, early warning, and alarm.

[0003] However, by means of a manual rotary resistance box, the load device is often damaged due to overvoltage. Content of the Utility Model

[0004] The utility model provides a load access protection circuit and an insulation testing device to solve the problem that the manual rotary resistance box test in the prior art is prone to overvoltage, resulting in damage to the load device.

[0005] In the first aspect, the utility model provides a load access protection circuit, including: an access module, a comparison module, and a protection module;

[0006] One end of the access module is connected to the signal terminal, the other end of the access module is connected to the input terminal of the comparison module, the output terminal of the comparison module is connected to the protection module, and the protection module is also connected to the access module;

[0007] The access module is used to access the load and set the overvoltage protection threshold, the comparison module is used to compare the real-time voltage with the overvoltage protection threshold and output a level signal, and the protection module is used to issue an alarm based on the level signal and disconnect the access of the load.

[0008] According to a load access protection circuit provided by the utility model, the access module includes: a load access circuit and a threshold setting circuit;

[0009] One end of the load access circuit is connected to the signal terminal, the other end of the load access circuit is connected to the load and then connected to the input terminal of the comparison module, one end of the threshold setting circuit is connected to the signal terminal, and the other end of the threshold setting circuit is connected to the input terminal of the comparison module;

[0010] The load access circuit is used to access the load to the test circuit, and the threshold setting circuit is used to set the overvoltage protection threshold of the test circuit.

[0011] According to a load access protection circuit provided by the utility model, the load access circuit includes: a first triode and a relay;

[0012] The base of the first triode is connected to the signal terminal, the collector of the first triode is connected to the first end of the relay, and the emitter of the first triode is grounded;

[0013] The second end of the relay is connected to the signal terminal, and the third and fourth ends of the relay are used to connect the load.

[0014] According to a load access protection circuit provided by the present invention, the threshold setting circuit includes: a second triode and a threshold adjustment unit;

[0015] The base of the second triode is connected to the signal terminal, the emitter of the second triode is connected to the threshold adjustment unit, and the collector of the second triode is connected to the base of the first triode;

[0016] One end of the threshold adjustment unit is connected to the power supply, and the other end of the threshold adjustment unit is connected to the input end of the comparison module.

[0017] According to a load access protection circuit provided by the present invention, the threshold adjustment unit includes: a first diode, a first opto-coupler switch, a first resistor and a second resistor;

[0018] The positive electrode of the first diode is connected to the power supply, and the negative electrode of the first diode is connected to the emitter of the second triode;

[0019] One end of the first opto-coupler switch is connected to the power supply through the first resistor, the other end of the first opto-coupler switch is connected to the input end of the comparison module, and the other end of the first opto-coupler switch is grounded through the second resistor.

[0020] According to a load access protection circuit provided by the present invention, the comparison module includes: an amplifier, a comparator and a detector;

[0021] The input end of the amplifier is connected to the load through the detector, the output end of the amplifier is connected to the input end of the comparator, and the output end of the comparator is connected to the protection module;

[0022] The amplifier is used to adjust the overvoltage protection threshold, and the comparator is used to compare the voltage thresholds.

[0023] According to a load access protection circuit provided by the present invention, the protection module includes: a second diode, a second opto-coupler switch and an alarm;

[0024] The positive electrode of the second diode is connected to the output terminal of the comparator, the negative electrode of the second diode is connected to the alarm, one end of the second opto-coupler switch is connected to the second diode, and the other end of the second opto-coupler switch is connected to the access module;

[0025] The second opto-coupler switch is used to control the access module to disconnect the load connection when the voltage is abnormal, and the alarm is used to give an alarm prompt.

[0026] According to a load access protection circuit provided by the present invention, it further includes: a delay unit;

[0027] One end of the delay unit is connected to the output terminal of the amplifier, and the other end of the delay unit is connected to the input terminal of the comparator;

[0028] The delay unit is used to extend the disconnection duration of the load.

[0029] According to a load access protection circuit provided by the present invention, the delay unit includes: a third resistor, a fourth resistor and a capacitor;

[0030] One end of the third resistor is connected to the output terminal of the amplifier, the other end of the third resistor is respectively connected to one end of the fourth resistor and the capacitor, the other end of the fourth resistor is connected to the input terminal of the comparator, and the other end of the capacitor is grounded.

[0031] On the other hand, the present invention also protects an insulation test device, including the load access protection circuit as described in any one of the above.

[0032] The load access protection circuit and the insulation test device provided by the present invention include: an access module, a comparison module and a protection module; one end of the access module is connected to a signal terminal, the other end of the access module is connected to the input terminal of the comparison module, the output terminal of the comparison module is connected to the protection module, and the protection module is also connected to the access module; the access module is used to access a load and set an overvoltage protection threshold, the comparison module is used to compare the real-time voltage with the overvoltage protection threshold and output a level signal, and the protection module is used to give an alarm based on the level signal and disconnect the access of the load. By providing a protection module, when overvoltage occurs, the access of the load can be disconnected in time, and overvoltage protection is effectively carried out. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a schematic diagram of the principle of the load access protection circuit provided by an embodiment of the present invention. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0036] Figure 1 It is a schematic diagram of the principle of the load access protection circuit provided by an embodiment of the present invention.

[0037] As Figure 1 shown, a load access protection circuit provided in this embodiment includes: an access module 1, a comparison module 2, and a protection module 3; one end of the access module 1 is connected to a signal terminal, the other end of the access module 1 is connected to the input end of the comparison module 2, the output end of the comparison module 2 is connected to the protection module 3, and the protection module 3 is also connected to the access module 1; the access module 1 is used to access a load and set an overvoltage protection threshold, the comparison module 2 is used to compare the real-time voltage with the overvoltage protection threshold and output a level signal, and the protection module 3 is used to issue an alarm and disconnect the access of the load based on the level signal.

[0038] In a specific implementation process, the signal terminal may be a level signal sent by a single-chip microcomputer, CTRL-LOWn is a level signal from a control terminal, and the function of the signal terminal is to drive the access module 1 to work so as to access the load into the circuit for an insulation test operation. As Figure 1 shown, the dots "R-LOAD+" and "R-LOAD-" represent the load access points, R-load represents the accessed load, and the size of the load is determined according to the selection of the operator. Only a case example is shown in the figure, that is, different values of R-load are adjusted by the different connections of "R-LOAD+" and "R-LOAD-".

[0039] When loads are connected to both ends of "R-LOAD+" and "R-LOAD-", and after a low-level signal is given to the signal terminal, the loads are successfully connected to the circuit. The access module 1 automatically determines the overvoltage protection threshold according to the resistance value of the connected load, the overcurrent magnitude, and the amplification factor of the amplifier 21 in the comparison module 2, that is, the maximum voltage that the load can withstand. At the same time, the overvoltage protection threshold is input into the comparison module 2. The comparison module 2 compares the real-time voltage with the overvoltage protection threshold. When the real-time voltage is greater than the overvoltage protection threshold, a high-level signal is output to control the protection module 3 to act, issue an alarm prompt, and feedback to adjust the access module 1 to disconnect the connection of the load, thereby protecting the test equipment and avoiding damage to the test equipment caused by overvoltage.

[0040] The access module 1 connects a preset-sized load to the circuit according to requirements for insulation testing. Voltage comparison is performed through the comparison module 2 by comparing the maximum overvoltage protection threshold that the connected load can withstand with the real-time voltage. By comparing the relationship between the real-time voltage and the overvoltage protection threshold during the test, it is determined whether the connected load will be damaged during the test. Therefore, during the test, when the real-time voltage is greater than the overvoltage protection threshold, it indicates that the load voltage at this time is too high and the load needs to be protected in a timely manner. Therefore, while the protection module 3 issues an alarm, a high level is input to the access module 1 through feedback adjustment to disconnect the connection between the load module and the circuit, thereby protecting the load.

[0041] Further, as Figure 1 shown, the access module 1 includes: a load access loop and a threshold setting loop; one end of the load access loop is connected to the signal terminal, the other end of the load access loop is connected to the load and then to the input terminal of the comparison module 2, one end of the threshold setting loop is connected to the signal terminal, and the other end of the threshold setting loop is connected to the input terminal of the comparison module 2; the load access loop is used to connect the load to the test circuit, and the threshold setting loop is used to set the overvoltage protection threshold of the test circuit.

[0042] Among them, the load access circuit includes: a first triode Q1 and a relay K; the base of the first triode Q1 is connected to the signal terminal, the collector of the first triode Q1 is connected to the first end of the relay K, and the emitter of the first triode Q1 is grounded; the second end of the relay K is connected to the signal terminal, and the third and fourth ends of the relay K are used to connect the load. The threshold setting circuit includes: a second triode Q2 and a threshold adjustment unit; the base of the second triode Q2 is connected to the signal terminal, the emitter of the second triode Q2 is connected to the threshold adjustment unit, and the collector of the second triode Q2 is connected to the base of the first triode Q1; one end of the threshold adjustment unit is connected to the power supply, and the other end of the threshold adjustment unit is connected to the input terminal of the comparison module 2. The threshold adjustment unit includes: a first diode D1, a first opto-coupler switch G1, a first resistor R1, and a second resistor R2; the positive electrode of the first diode D1 is connected to the power supply, and the negative electrode of the first diode D1 is connected to the emitter of the second triode Q2; one end of the first opto-coupler switch G1 is connected to the power supply through the first resistor R1, the other end of the first opto-coupler switch G1 is connected to the input terminal of the comparison module 2, and the other end of the first opto-coupler switch G1 is grounded through the second resistor R2.

[0043] Specifically, when the load is accessed, the control terminal inputs a low-level signal to the base of the second triode Q2, the second triode Q2 conducts, and then the first triode Q1 conducts, and the relay K is attracted, so that the load is successfully connected to the circuit. At this time, since the second triode Q2 conducts, the first diode D1 also conducts, and the light emission of the first diode D1 causes the first opto-coupler switch G1 to close. At this time, an overvoltage protection threshold is formed between the first opto-coupler switch G1 and the second resistor R2 and sent to the comparison module 2. Among them, the second resistor R2 is adjustable. Since the overvoltage protection threshold is determined after the load is accessed, by adjusting the size of the second resistor R2, the corresponding overvoltage protection threshold is accurately output to the comparison module 2.

[0044] The calculation of the overvoltage protection threshold is as shown in formula (1):

[0045] Vrefx = Ip * Rshunt * Gv (1)

[0046] Among them, Vrefx represents the overvoltage protection threshold, Ip represents the current protection threshold, Rshunt represents the shunt resistor value, and Gv represents the amplification factor.

[0047] After the load is accessed, Ip and Rshunt are determined. The amplification factor Gv of the amplifier 21 in the comparison module 2 can be determined or adjustable. Therefore, the overvoltage protection threshold is determined. Then, by adjusting the second resistor R2, a value equal to the overvoltage protection threshold can be output to the comparator 22 in the comparison module 2.

[0048] Furthermore, asFigure 1 As shown, based on the above embodiments, the comparison module 2 in this embodiment includes: an amplifier 21, a comparator 22, and a detector 23; the input end of the amplifier 21 is connected to the load through the detector 23, the output end of the amplifier 21 is connected to the input end of the comparator 22, and the output end of the comparator 22 is connected to the protection module 3; the amplifier 21 is used to adjust the overvoltage protection threshold, the comparator 22 is used to compare the voltage threshold, and the detector is used for current detection or overload detection.

[0049] Specifically, the detector is a resistor Shunt, which constitutes an overcurrent detection circuit for the load. After converting the current into a voltage, it is input to the amplifier 21. After amplifying the voltage signal by a preset multiple, it is input to the input end of the comparator 22 and compared with the overvoltage protection threshold at the other input end of the comparator 22. When the comparison result is that the real-time threshold output by the amplifier 21 is less than the overvoltage protection threshold, the comparator 22 outputs a low level, and the protection module 3 does not work, and the current test operation can be continued. When the real-time threshold output by the amplifier 21 is greater than or equal to the overvoltage protection threshold, it indicates that the load voltage is too high at this time. The comparator 22 outputs a high level. At this time, the protection module 3 starts to work, gives an alarm, and at the same time feeds back a high level to the first triode Q1. The first triode Q1 is turned off, so that the relay K is turned off, and the load is disconnected from the circuit.

[0050] And as Figure 1 shown, the protection module 3 includes: a second diode D2, a second opto-coupler switch G2, and an alarm 31; the positive pole of the second diode D2 is connected to the output end of the comparator 22, the negative pole of the second diode D2 is connected to the alarm 31, one end of the second opto-coupler switch G2 is connected to the second diode D2, and the other end of the second opto-coupler switch G2 is connected to the access module 1; the second opto-coupler switch G2 is used to control the access module 1 to disconnect the load connection when the voltage is abnormal, and the alarm 31 is used to give an alarm prompt.

[0051] Specifically, when the comparator 22 outputs a high level, the second diode D2 conducts and emits light, the second opto-coupler switch G2 closes, and the output signal PRT of the second opto-coupler switch G2 is output to the base of the first triode Q1. The first triode Q1 does not conduct, and the relay K is turned off, and the load is not connected to the circuit. After the second diode D2 conducts, the alarm 31 starts to work and gives an alarm prompt, including light or sound prompts, etc. The light alarm can also be directly realized through the second diode D2 to remind relevant personnel to perform maintenance or stop the test in time. Thus, the load is protected, and the damage of the insulation test equipment is effectively avoided.

[0052] Furthermore, as Figure 1As shown in the figure, it further includes a delay unit. One end of the delay unit is connected to the output end of the amplifier 21, and the other end of the delay unit is connected to the input end of the comparator 22. The delay unit is used to extend the disconnection duration of the load. The delay unit includes a third resistor R3, a fourth resistor R4, and a capacitor. One end of the third resistor R3 is connected to the output end of the amplifier 21, the other end of the third resistor R3 is respectively connected to one end of the fourth resistor R4 and the capacitor, the other end of the fourth resistor R4 is connected to the input end of the comparator 22, and the other end of the capacitor is grounded.

[0053] Specifically, when the voltage is abnormal, the relay K disconnects. Then, after the relay K is restored to the closed state, in order to ensure effective protection of the load, through the sampling and holding function of the capacitor, the duration for the load to be reconnected to the circuit is effectively extended, making the disconnection time longer and better ensuring that the circuit returns to the initial state.

[0054] The load access protection circuit of the present utility model realizes the isolation of load access through the first optocoupler switch G1, avoids the influence of high voltage on the circuit, realizes high-low voltage isolation, and is more convenient for application in high-voltage systems. And when the load voltage is abnormal, the load is isolated from the circuit, effectively isolating and protecting the load.

[0055] Based on the same general inventive concept, the present utility model also protects an insulation testing device, which includes the load access protection circuit of any of the above embodiments. The insulation testing device can be an automated testing device.

[0056] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0057] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, also by hardware. Based on such an understanding, the above technical solutions, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A load access protection circuit, characterized in that: include: Access module, comparison module and protection module; One end of the access module is connected to the signal end, the other end of the access module is connected to the input end of the comparison module, the output end of the comparison module is connected to the protection module, and the protection module is also connected to the access module; The access module is used to access the load and set the overvoltage protection threshold, the comparison module is used to compare the real-time voltage with the overvoltage protection threshold, output a level signal, and the protection module is used to issue an alarm based on the level signal and disconnect the load; The comparison module includes: an amplifier, a comparator and a detector; the input end of the amplifier is connected to the load through the detector, the output end of the amplifier is connected to the input end of the comparator, and the output end of the comparator is connected to the protection module; the amplifier is used to adjust the overvoltage protection threshold, and the comparator is used to compare the voltage threshold; The protection module includes: a second diode, a second optocoupler switch and an alarm; the anode of the second diode is connected to the output end of the comparator, the cathode of the second diode is connected to the alarm, one end of the second optocoupler switch is connected to the second diode, and the other end of the second optocoupler switch is connected to the access module; the second optocoupler switch is used to control the access module to disconnect the load when the voltage is abnormal, and the alarm is used to issue an alarm prompt.

2. The load access protection circuit according to claim 1, characterized in that: The access module includes: a load access circuit and a threshold setting circuit; One end of the load access loop is connected to the signal end, the other end of the load access loop is connected to the load and then connected to the input end of the comparison module, one end of the threshold setting loop is connected to the signal end, and the other end of the threshold setting loop is connected to the input end of the comparison module; The load access circuit is used to connect the load to the test circuit, and the threshold setting circuit is used to set the overvoltage protection threshold of the test circuit.

3. The load access protection circuit according to claim 2, characterized in that: The load access circuit includes: a first transistor and a relay; The base of the first transistor is connected to the signal end, the collector of the first transistor is connected to the first end of the relay, and the emitter of the first transistor is grounded; The second end of the relay is connected to the signal end, and the third end and the fourth end of the relay are used to connect to a load.

4. The load access protection circuit according to claim 3, characterized in that: The threshold setting loop includes: a second triode and a threshold adjustment unit; The base of the second transistor is connected to the signal terminal, the emitter of the second transistor is connected to the threshold adjustment unit, and the collector of the second transistor is connected to the base of the first transistor; One end of the threshold adjustment unit is connected to a power supply, and the other end of the threshold adjustment unit is connected to an input end of the comparison module.

5. The load access protection circuit according to claim 4, characterized in that: The threshold adjustment unit includes: a first diode, a first optical coupler switch, a first resistor and a second resistor; The positive electrode of the first diode is connected to a power supply, and the negative electrode of the first diode is connected to the emitter of the second transistor; One end of the first optocoupler switch is connected to a power supply through the first resistor, the other end of the first optocoupler switch is connected to an input end of the comparison module, and the other end of the first optocoupler switch is grounded through the second resistor.

6. The load access protection circuit according to claim 1, characterized in that: Also includes: Delay unit; One end of the delay unit is connected to the output end of the amplifier, and the other end of the delay unit is connected to the input end of the comparator; The delay unit is used to extend the disconnection time of the load.

7. The load access protection circuit according to claim 6, characterized in that: The delay unit comprises: a third resistor, a fourth resistor and a capacitor; One end of the third resistor is connected to the output end of the amplifier, the other end of the third resistor is respectively connected to the fourth resistor and one end of the capacitor, the other end of the fourth resistor is connected to the input end of the comparator, and the other end of the capacitor is grounded.

8. An insulation testing device, characterized in that: It comprises a load access protection circuit as described in any one of claims 1 to 7.

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