A substation safety dedicated multimeter

Abstract

The application is suitable for the field of instruments and meters, and provides a transformer substation safety special-purpose multimeter, which comprises a multimeter measuring module, a display module connected with the multimeter measuring module, a sampling module for collecting data of a measured device, a connecting assembly for connecting the multimeter measuring module and the sampling module with the measured device, a main control module and a logic operation module for calculating loop current of the measured device, wherein the main control module is connected with the logic operation module, and the main control module is also connected with the display module and the sampling module, and a warning module for cooperating with the main control module to safely judge the loop current, wherein the warning module is connected with the main control module and the logic operation module respectively. The application reduces safety accidents caused by incorrect operation of the multimeter by maintenance personnel, improves work efficiency, has strong engineering practicability, and is convenient to popularize.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of instruments and meters, and particularly relates to a safety multimeter special for a transformer substation. BACKGROUND

[0002] The multimeter can measure various electrical characteristics such as voltage, current and resistance of a circuit, and thus becomes an important tool indispensable to the power industry. With the continuous development of electronic technology, the functions and measurement accuracy of the multimeter are continuously improved, but the anti-misoperation function of the multimeter develops slowly. The wrong operation of the multimeter often causes damage to the multimeter and the measured equipment, for example, the current range measures the voltage circuit, the ohm range measures the live circuit, and so on. Especially, the wrong use of the multimeter by the maintenance personnel in important places such as transformer substations and power stations will not only cause damage to the multimeter, but also cause damage to the power equipment, switch tripping and protection misoperation and other serious accidents.

[0003] Through the analysis of the working principle of the multimeter, it is found that the root cause of the accident caused by the multimeter is that the multimeter and the test probe form a short circuit with the measured equipment, which causes a large current to impact the multimeter and the measured equipment, thereby causing irreversible damage to the multimeter and the measured equipment.

[0004] There are two main solutions to this problem on the market: the first one mainly uses component protection, and the second one uses protection circuit protection. The component protection scheme mainly introduces protection components such as self-resetting fuses, current limiting resistors, fast fuses and fuse resistors in front of the multimeter measurement circuit. When a large current impacts, the protection components are burned out, which cannot form a complete circuit to protect the multimeter and the measured equipment. If it is used again, the protection components need to be re-soldered. The protection circuit scheme mainly adds a protection circuit module to the test probe or test cable based on the original structure of the multimeter, thereby realizing the protection function of the multimeter. For example, the patent CN212301664U discloses a safety multimeter special for power, which designs a protection circuit on the probe of the multimeter. The circuit mainly realizes an ideal current constant current source through a first current constant current circuit. When the current of the test probe is less than the constant current source, the constant current source presents impedance. When the current flowing through the probe increases, the impedance of the constant current source immediately increases, so that the current flowing through the probe is constant at the set value, thereby limiting the current and avoiding the impact of large current on the multimeter and the measured equipment. In order to facilitate the test of alternating current signal, a first constant current source and a second constant current source are connected in reverse parallel. Since the first constant current diode and the second constant current diode exist in the first constant current source and the second constant current source, the diode voltage drop is large when the ohm range is tested, which has a great influence on the measurement of low ohm value. Therefore, a bypass switch is designed to short-circuit the protection circuit and realize the correct measurement of resistance.

[0005] In the above two schemes, the first scheme is less used for the protection of the multimeter due to the limitation of the electrical characteristics of the components. The protection circuit of the second scheme is simple in structure, but a protection circuit module needs to be added between the test probe or the test cable to realize the protection of the multimeter, and the protection limit only depends on the parameters of the protection circuit module, which belongs to passive protection. When the input signal exceeds the limit parameters of the protection circuit module, the protection circuit loses the protection function. At the same time, the addition of the module leads to the increase of the overall structure of the multimeter, which reduces the portability of the multimeter to a certain extent. Therefore, there is still a lack of a special multimeter for substation safety in the prior art, which has active protection, parameter resolution of the meter, and intelligent early warning. SUMMARY

[0006] The present application aims to provide a special multimeter for substation safety, which aims to solve the problems in the above technical background.

[0007] The present application is implemented as follows: a special multimeter for substation safety, comprising:

[0008] a multimeter measurement module and a display module connected to the multimeter measurement module;

[0009] a sampling module for collecting data of the measured equipment;

[0010] a connecting assembly for connecting the multimeter measurement module and the sampling module with the measured equipment;

[0011] a main control module and a logic operation module for calculating the loop current of the measured equipment, the main control module being connected to the logic operation module, and the main control module being further connected to the display module and the sampling module; and

[0012] a warning module for cooperating with the main control module to safely judge the loop current, the warning module being connected to the main control module and the logic operation module respectively.

[0013] As a further scheme of the present application: the multimeter measurement module comprises an alternating voltage measurement module, a diode measurement module, a capacitor measurement module, a conduction measurement module, and a resistance measurement module.

[0014] As a further scheme of the present application: the sampling module comprises a rectifier circuit, a matching circuit, and an in-table DC voltage measurement circuit, the rectifier circuit being used for connecting the connecting assembly and the matching circuit, and the in-table DC voltage measurement circuit being used for connecting the matching circuit and the main control module.

[0015] As a further scheme of the present application: the matching circuit comprises a matching resistor two and a matching resistor one.

[0016] As a further embodiment of the present invention: the matching circuit further includes matching resistor three, matching resistor four, matching resistor five, other matching resistors and multi-point relay switch, and the DC voltage measurement circuit inside the meter is connected in parallel with matching resistor two and matching resistor one, matching resistor three, matching resistor four, matching resistor five and other matching resistors;

[0017] The matching resistors 2, 1, 3, 4, 5 and other matching resistors are connected in series with the multi-point relay switch, and one end of the multi-point relay switch is grounded.

[0018] As a further aspect of the present invention, the resistance of the first matching resistor is 0 ohms.

[0019] As a further aspect of the present invention: the connection component includes a normally open current range switch, a signal input module, and a normally closed current range reverse phase switch;

[0020] The signal input module is connected to the device under test via the positive and negative terminals of the transducer.

[0021] The normally open current range switch is used for connecting the signal input module and the sampling module;

[0022] The current range reverse phase normally closed switch is used for the connection between the signal input module and the multimeter measurement module;

[0023] The normally open switch for the current range and the normally closed switch for the reverse current range are a pair of reverse switches.

[0024] As a further aspect of the present invention: the logic operation module includes a device under test impedance simulation calculation module and a device under test maximum current simulation calculation module;

[0025] The main control module is connected to one end of the device under test and the impedance simulation calculation module, the other end of the device under test voltage and impedance simulation calculation module is connected to one end of the device under test maximum current simulation calculation module, and the other end of the device under test maximum current simulation calculation module is connected to the early warning module.

[0026] As a further aspect of the present invention: the early warning module includes an alarm light and a substation safety current threshold judgment module;

[0027] The main control module is connected to one end of the substation safety current threshold judgment module, and the other end of the substation safety current threshold judgment module is connected to the alarm light.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention utilizes an internal DC voltage measurement circuit, sampling module, main control module, logic operation module, early warning module, and display module to complete the active protection function of the current range of the multimeter for substation safety. Under the action of the main control module, logic simulation calculation is performed to calculate the equipment impedance and equipment voltage of the tested equipment. The maximum and minimum current of the tested equipment is simulated using the impedance and voltage values. The obtained maximum and minimum current is compared with the threshold current of the substation equipment. If it exceeds the threshold range, the early warning module is activated, and the display module displays the magnitude of the maximum and minimum current, thus completing the active protection of the multimeter current range.

[0030] This substation safety multimeter has a high level of safety. Through active protection of the current range, it can protect the multimeter and the equipment under test. Especially in the substation environment, it effectively reduces safety accidents caused by maintenance personnel's misoperation of the multimeter, while improving work efficiency. It is highly practical and easy to promote. Attached Figure Description

[0031] Figure 1 This is a diagram illustrating the usage of a substation safety-specific multimeter, as provided in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of a substation safety-specific multimeter provided in an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram illustrating the anti-maloperation protection principle of a substation safety multimeter provided in an embodiment of the present invention.

[0034] In the attached diagram: 1. Multimeter measurement module; 2. Positive probe; 3. Negative probe; 4. Signal input module; 5. Normally open current range switch; 6. Sampling module; 7. Main control module; 8. Logic operation module; 9. Warning module; 10. Display module; 11. Normally closed current range reverse switch; 12. Device under test; 1-1. AC voltage measurement module; 1-2. Diode measurement module; 1-3. Capacitance measurement module; 1-4. Continuity measurement module; 1-5. Resistance measurement module; 6-1. Rectifier circuit; 6-2. Matching circuit; 6-3. Matching resistor two; 6-4. Matching resistor one; 6-5. Internal DC voltage measurement circuit; 6-6. Matching resistor three; 6-7. Matching resistor four; 6-8. Matching resistor five; 6-9. Other matching resistors (R 匹配X ); 6-10, Multi-point relay switch; 8-1, Test equipment and impedance simulation calculation module; 8-2, Test equipment maximum current simulation calculation module; 9-1, Alarm light; 9-2, Substation safety current threshold judgment module; 12-1, Equipment impedance (R); 12-2, Equipment voltage (U); 12-3, Loop current (I) 回 ). Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0036] Please see Figures 1-3 This invention provides a substation safety-specific multimeter, which includes:

[0037] Multimeter measurement module 1 and display module 10 connected to multimeter measurement module 1;

[0038] Sampling module 6 for collecting data from the device under test 12;

[0039] A connection component is used for the connection between the multimeter measurement module 1 and the device under test 12, and between the sampling module 6 and the device under test 12;

[0040] Used to calculate the loop current (I) of the device under test 12 回 The main control module 7 and the logic operation module 8 of 12-3 are connected, and the main control module 7 is also connected to the display module 10 and the sampling module 6.

[0041] And for use with the main control module 7 pairs of loop current (I 回 )12-3 The early warning module 9 performs safety judgment, and the early warning module 9 is connected to the main control module 7 and the logic operation module 8 respectively.

[0042] In an embodiment of the present invention, through the coordinated arrangement of the sampling module 6, the main control module 7, and the logic operation module 8, the device voltage (U) 12-2 and the device impedance (R) 12-1 can be calculated and displayed on the multimeter screen via the display module 10. Through the coordinated arrangement of the main control module 7 and the sampling module 6, the loop current 12-3 (IL) of the device under test 12 can be calculated. 回 ), and through the coordination of the early warning module 9 and the main control module, it can monitor the loop current 12-3 (I 回 Conduct a safety assessment;

[0043] Through internal parameter decoding and simulation calculations, the equipment voltage (U)12-2, equipment impedance (R)12-1, and loop current (I) are calculated. 回 )12-3 achieves the current range misoperation protection function;

[0044] Logic module 8 rapidly completes the calculation of device voltage (U) 12-2, device impedance (R) 12-1, and loop current (I) using a high-performance processor. 回 The calculation of 12-3 has the characteristics of low power consumption, high level of intelligence, fast response speed and high reliability;

[0045] This substation safety multimeter features a simple structure, high portability, and comprehensive functionality and compatibility, and is compatible with all measurement functions and probe models of multimeters on the market.

[0046] In one embodiment of the present invention, please refer to Figure 2 The multimeter measurement module 1 includes an AC voltage measurement module 1-1, a diode measurement module 1-2, a capacitance measurement module 1-3, a continuity measurement module 1-4, and a resistance measurement module 1-5.

[0047] By setting up AC voltage measurement module 1-1, diode measurement module 1-2, capacitance measurement module 1-3, continuity measurement module 1-4, and resistance measurement module 1-5, different data can be measured, making it convenient for users to select different ranges of the multimeter (such as AC / DC voltage range, continuity range, resistance range, diode range, and capacitance range).

[0048] In one embodiment of the present invention, please refer to Figure 2 The sampling module 6 includes a rectifier circuit 6-1, a matching circuit 6-2, and an internal DC voltage measurement circuit 6-5. The rectifier circuit 6-1 is used to connect the component and the matching circuit 6-2, and the internal DC voltage measurement circuit 6-5 is used to connect the matching circuit 6-2 and the main control module 7.

[0049] The matching circuit 6-2 includes matching resistor 6-3 and matching resistor 6-4;

[0050] The matching circuit 6-2 also includes matching resistor three 6-6, matching resistor four 6-7, matching resistor five 6-8, other matching resistors 6-9, and multi-point relay switch 6-10. The DC voltage measurement circuit 6-5 inside the meter is connected in parallel with matching resistor two 6-3, matching resistor one 6-4, matching resistor three 6-6, matching resistor four 6-7, matching resistor five 6-8, and other matching resistors 6-9.

[0051] The matching resistor 2 6-3, matching resistor 1 6-4, matching resistor 3 6-6, matching resistor 4 6-7, matching resistor 5 6-8 and other matching resistors 6-9 are connected in series with the multi-point relay switch 6-10, and one end of the multi-point relay switch 6-10 is grounded.

[0052] The resistance of the first matching resistor 6-4 is 0 ohms. The resistance values ​​of the second matching resistor 6-3, the third matching resistor 6-6, the fourth matching resistor 6-7, the fifth matching resistor 6-8, and the other matching resistors 6-9 need to be determined according to the actual maximum safe current of the substation.

[0053] In this embodiment, matching resistors of different resistance values ​​in the matching circuit 6-2 (i.e., matching resistor 2 6-3, matching resistor 1 6-4, matching resistor 3 6-6, matching resistor 4 6-7, matching resistor 5 6-8, and other matching resistors 6-9) are connected in series with the connecting component.

[0054] In one embodiment of the present invention, please refer to Figure 2 and Figure 3 The connection components include a current range normally open switch 5, a signal input module 4, and a current range reverse normally closed switch 11;

[0055] The signal input module 4 is connected to the device under test 12 via the positive terminal 2 and the negative terminal 3 of the transducer.

[0056] The normally open current range switch 5 is used for the connection between the signal input module 4 and the sampling module 6;

[0057] The current range reverse phase normally closed switch 11 is used for the connection between the signal input module 4 and the multimeter measurement module 1;

[0058] The normally open current range switch 5 and the normally closed current range switch 11 are a pair of reverse-phase switches.

[0059] In this embodiment, the normally open current range switch 5 is connected to one end of the rectifier circuit 6-1, the other end of the rectifier circuit 6-1 is connected to the matching circuit 6-2, the other end of the matching circuit 6-2 is connected to the DC voltage measurement circuit 6-5 inside the meter, and the other end of the DC voltage measurement circuit 6-5 inside the meter is connected to the main control module 7.

[0060] The normally open current range switch 5 and the normally closed current range switch 11 are a pair of reverse switches. That is, when the normally open current range switch 5 is closed, the normally closed current range switch 11 must be open, and vice versa. The two cannot be in the open or closed state at the same time.

[0061] By connecting the matching resistors of different values ​​in the matching circuit 6-2 (i.e., matching resistor 2 6-3, matching resistor 1 6-4, matching resistor 3 6-6, matching resistor 4 6-7, matching resistor 5 6-8, and other matching resistors 6-9) in series with the signal input module 4, the device impedance (R) 12-1, device voltage (U) 12-2, and loop current (I) of the device under test 12 can be obtained by series analysis. 回 The value of 12-3 is displayed in the display module 10, and the loop current (I) is displayed.回 )12-3 size;

[0062] The series analysis method measures the voltage (U) across the matching resistor using the DC voltage measuring circuit 6-5 inside the meter. 表 Then, by controlling the multi-point relay switch 6-10 to conduct matching resistors of different resistance values, the current in the conducting circuit (I) is calculated. 回 )12-3, since the currents in a series circuit are equal, the loop current (I) formed by the equipment impedance (R)12-1, matching resistor 1-6-4, and matching resistor 2-6-3 is equal to the current in the circuit. 回 Since 12-3 is the same, the equipment impedance (R)12-1 and equipment voltage (U)12-2 of the tested equipment can be calculated.

[0063] The specific calculation method of the aforementioned cascade analysis is as follows:

[0064]

[0065]

[0066] The series analysis method described above can calculate the equipment impedance (R) using formulas (1) and (2).

[0067] 12-1 Equipment voltage (U) 12-2 and loop current (I) 回 )12-3.

[0068] In one embodiment of the present invention, please refer to Figure 2 The logic operation module 8 includes a device under test impedance simulation calculation module 8-1 and a device under test maximum current simulation calculation module 8-2.

[0069] The main control module 7 is connected to one end of the device under test and impedance simulation calculation module 8-1, the other end of the device under test voltage and impedance simulation calculation module 8-1 is connected to one end of the device under test maximum current simulation calculation module 8-2, and the other end of the device under test maximum current simulation calculation module 8-2 is connected to the early warning module 9.

[0070] In one embodiment of the present invention, please refer to Figure 2 The early warning module 9 includes an alarm light 9-1 and a substation safety current threshold judgment module 9-2;

[0071] The main control module 7 is connected to one end of the substation safety current threshold judgment module 9-2, and the other end of the substation safety current threshold judgment module 9-2 is connected to the alarm light 9-1.

[0072] In this embodiment, the calculated loop current (I) is determined by the substation safety current threshold judgment module 9-2. 回)12-3 is compared with the substation's safe current threshold. If it exceeds the threshold range, alarm light 9-1 will emit a light alarm, and display module 4 will display the loop current (I). 回 If the value of 12-3 does not exceed the threshold range, then only the loop current (I) will be displayed on display module 4. 回 )12-3 size.

[0073] In summary, the working principle of this invention is as follows:

[0074] When the multimeter is used in AC / DC voltage range, conduction range, resistance range, diode range, or capacitance range, the measured signal passes through the positive terminal 2 and negative terminal 3 of the meter probes and directly enters the respective measurement circuits through the current range inverted normally closed switch 11 for measurement. The measurement result is displayed on the screen by the display module 4. If the current range is used for measurement, the current range normally open switch 5 is closed first, and the current range inverted normally closed switch 11 is opened. The signal input module 4 cannot be directly tested by the multimeter measurement module 1 circuit. The signal input module 4 inputs the signal to the sampling module 6. The signal enters the matching circuit 6-2 through the rectifier circuit 6-1. The matching resistor of the matching circuit 6-2 converts the measured input signal into the device voltage (U)12-2. The voltage U across the matching resistor can be measured through the DC voltage measurement circuit 6-5 inside the meter. The device voltage (U)12-2, device impedance (R)12-1, and loop current (I) can be calculated through equations (1) and (2). 回 )12-3;

[0075] For details on the working principle of the current range's misoperation protection, please refer to... Figure 3 The number of matching resistors in the matching circuit 6-2 includes, but is not limited to, matching resistor one 6-4, matching resistor two 6-3, matching resistor three 6-6, matching resistor four 6-7 and matching resistor five 6-8, etc., and the resistance value and number are matched according to the size of the substation safety threshold current.

[0076] The protection process of the substation safety multimeter is as follows: The device under test 12 is connected in series with the matching circuit 6-2, and the DC voltage measuring circuit 6-5 inside the meter is connected in parallel with the matching resistor. The voltage U across its two ends is measured and the measured value U is uploaded to the main control module 7. The main control module 7 controls the multi-point relay switch 6-10 to sequentially turn on the matching resistors 6-3, 6-6, 6-7, and 6-8. The logic operation module 8 calculates the device voltage (U) 12-2 and the device impedance (R) 12-1 through equations (1) and (2) and stores the value in the main control module 7. At the same time, the multi-point relay switch 6-10 turns on the 0-ohm matching resistor 6-4 and calculates the loop current (I) through equation (2). 回 )12-3, through the main control module 7 and the substation safety current threshold judgment module 9-2, the outgoing loop current (I) is determined.回 If the current is compared with the substation's safe current threshold (12-3), and exceeds the threshold range, alarm light 9-1 will emit a light alarm, and display module 4 will display the loop current (I). 回 If the value of 12-3 does not exceed the threshold range, then only the loop current (I) will be displayed on display module 4. 回 )12-3 size.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multimeter specifically designed for substation safety, comprising a multimeter measurement module and a display module connected to the multimeter measurement module, characterized in that, Also includes: A sampling module used to collect data from the device under test; A connection component is used for connecting the multimeter measurement module and the device under test, as well as the sampling module and the device under test; The main control module and the logic operation module are used to calculate the loop current of the device under test. The main control module is connected to the logic operation module, and the main control module is also connected to the display module and the sampling module. And an early warning module for cooperating with the main control module to make a safety judgment on the loop current, wherein the early warning module is connected to the main control module and the logic operation module respectively; The multimeter measurement module includes an AC voltage measurement module, a diode measurement module, a capacitance measurement module, a continuity measurement module, and a resistance measurement module; The sampling module includes a rectifier circuit, a matching circuit, and an internal DC voltage measurement circuit. The rectifier circuit is used to connect the components and the matching circuit, and the internal DC voltage measurement circuit is used to connect the matching circuit and the main control module. The logic operation module includes an impedance simulation calculation module for the device under test and a maximum current simulation calculation module for the device under test. The main control module is connected to one end of the device under test and the impedance simulation calculation module, the other end of the device under test voltage and impedance simulation calculation module is connected to one end of the device under test maximum current simulation calculation module, and the other end of the device under test maximum current simulation calculation module is connected to the early warning module.

2. The substation safety-specific multimeter according to claim 1, characterized in that, The matching circuit includes matching resistor two and matching resistor one.

3. The substation safety-specific multimeter according to claim 2, characterized in that, The matching circuit also includes matching resistor three, matching resistor four, matching resistor five, other matching resistors, and a multi-point relay switch. The DC voltage measurement circuit inside the meter is connected in parallel with matching resistor two, matching resistor one, matching resistor three, matching resistor four, matching resistor five, and other matching resistors. The matching resistors 2, 1, 3, 4, 5 and other matching resistors are connected in series with the multi-point relay switch, and one end of the multi-point relay switch is grounded.

4. The substation safety-specific multimeter according to claim 1, characterized in that, The resistance of the first matching resistor is 0 ohms.

5. The substation safety-specific multimeter according to claim 1, characterized in that, The connection components include a current range normally open switch, a signal input module, and a current range reverse normally closed switch; The signal input module is connected to the device under test via the positive and negative terminals of the transducer. The normally open current range switch is used for connecting the signal input module and the sampling module; The current range reverse phase normally closed switch is used for the connection between the signal input module and the multimeter measurement module; The normally open switch for the current range and the normally closed switch for the reverse current range are a pair of reverse switches.

6. The substation safety-specific multimeter according to claim 1, characterized in that, The early warning module includes an alarm light and a substation safety current threshold judgment module; The main control module is connected to one end of the substation safety current threshold judgment module, and the other end of the substation safety current threshold judgment module is connected to the alarm light.

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