CN110780175A - Multifunctional high-voltage electrical equipment insulation testing device - Google Patents

Abstract

The invention discloses a multifunctional high-voltage electrical equipment insulation testing device, comprising a measuring circuit, a variable frequency power supply, a step-up transformer, a control panel, a Cx reverse wiring current detection module, a Cx positive wiring current detection module and a resistance testing module. The terminal is connected to the main power supply, and the output terminal is connected to the step-up transformer. The step-up transformer is sequentially connected to the CVT isolation module and the Cx reverse wiring current detection module. The step-up transformer is also connected to the CVT low-voltage output terminal. The CVT reverse wire and the internal capacitance Cn are connected to the measurement circuit, the measurement circuit is connected to the Cx reverse wiring current detection module, the Cx positive wiring current detection module and the resistance test module are connected to the measurement circuit, and the measurement circuit is connected to the control panel. The invention can realize insulation resistance test and dielectric loss multi-channel test, and while ensuring the accuracy of test data, the operation time and operation risk are reduced.

Description

A multifunctional high-voltage electrical equipment insulation test device

technical field

The invention belongs to the technical field of electrical equipment insulation testing equipment, and relates to a multifunctional high-voltage electrical equipment insulation testing device.

Background technique

At present, in the maintenance test of substation equipment, each equipment requires dielectric loss and insulation resistance test. It is necessary to carry a dielectric loss tester and an insulation resistance tester, and separate wiring is required. The test site wiring is cumbersome, the test work time is long, and the efficiency is low. Repeated disconnection may also cause some damage to the device under test.

In order to solve the existing problems, it is proposed to realize the function of testing dielectric loss and insulation resistance at the same time with one instrument, adding the insulation resistance test function on the basis of the dielectric loss tester, and has the dielectric loss multi-channel test, which can measure various high-voltage electrical equipment. Dielectric loss, insulation resistance, absorption ratio and polarization index (such as transformers, reactors, capacitors, circuit breakers, mutual inductors, etc.), and are also suitable for the measurement of dielectric loss and insulation resistance of power cables. Operators only need one device for a single connection to complete the dielectric loss test and insulation resistance test. While ensuring the accuracy of the test data, the operation time and operation risk are reduced.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a multifunctional high-voltage electrical equipment insulation testing device to solve the problems existing in the prior art.

The technical scheme adopted by the present invention is: a multifunctional high-voltage electrical equipment insulation testing device, comprising a measuring circuit, a variable frequency power supply, a step-up transformer, a control panel, a Cx reverse wiring current detection module, a Cx positive wiring current detection module and a resistance tester Module, the input end of the variable frequency power supply is connected to the main power supply, the output end is connected to the step-up transformer, the high-voltage output end of the step-up transformer is sequentially connected to the CVT isolation module and the C x reverse wiring current detection module, and the low-voltage output end of the step-up transformer is also connected to a CVT The low-voltage output terminal, the high-voltage output terminal of the step-up transformer is connected to the measurement circuit through the parallel CVT reverse line and the internal capacitor Cn, and the measurement circuit is connected to the Cx reverse wiring current detection module through the digital isolation communication module, and the Cx positive wiring current detection module and The resistance test module is connected to the measurement circuit, the measurement circuit is connected to the control panel, and the control panel is connected to the display and keys.

Preferably, the Cx reverse wiring current detection module, the Cx positive wiring current detection module, the output terminal of the resistance test module, and the CVT low-voltage output terminal are all provided with plug-in ports, and the plug-in ports are installed on the tester housing.

Preferably, the above-mentioned variable frequency power supply adopts an SPWM switching circuit to generate a high-power sine wave regulated output.

Preferably, the above-mentioned control panel is also connected with a printer and a communication interface.

Beneficial effects of the present invention: compared with the prior art, the effects of the present invention are as follows:

1) The present invention solves the problem of complicated wiring for testing dielectric loss and insulation resistance, and the instrument is inconvenient to carry; it saves time and effort, and the tester can measure the dielectric loss and insulation resistance at the same time after wiring, which reduces the workload on site, reduces costs, and improves efficiency;

2) The present invention has the multi-channel test function of dielectric loss, which can test the dielectric loss data of positive wiring of 4 samples at the same time; such as testing the dielectric loss of transformer bushings, four bushing dielectric loss tests can be completed in one connection; Climb down the hassle of changing test leads frequently. At the same time, it also ensures the safety of personnel and equipment;

3) The instrument has its own data printing and storage function, which is convenient for management and analysis of test data.

When the temperature in the exhaust pipe reaches 150-200°C, connect it to the hot gas outlet pipe. On the one hand, it can be effectively used to improve the fuel utilization rate; to the surrounding, affecting the health of the operator.

Description of drawings

Fig. 1 is the principle schematic diagram of the present invention;

Fig. 2 is a schematic diagram of a control software operation flow;

Figure 3 is a block diagram of the AC-DC conversion principle;

Figure 4 is the wiring diagram of the multi-pass test function;

Figure 5 is the wiring diagram of the insulation resistance test function.

Detailed ways

The present invention will be further introduced below with reference to the accompanying drawings and specific embodiments.

Embodiment 1: As shown in Figures 1-5, a multifunctional high-voltage electrical equipment insulation test device, including a measurement circuit, a variable frequency power supply, a step-up transformer, a control panel, a Cx reverse wiring current detection module, and a Cx positive wiring current. Detection module and resistance test module, the input end of the variable frequency power supply is connected to the main power supply, the output end is connected to the step-up transformer, and the high-voltage output end of the step-up transformer is connected to the CVT isolation module and the C x reverse wiring current detection module in turn, and the low-voltage output of the step-up transformer is connected. The terminal is also connected with the CVT low-voltage output terminal. The high-voltage output terminal of the step-up transformer is connected to the measurement circuit through the parallel CVT inverted line and the internal capacitor Cn. The measurement circuit is connected to the Cx reverse wiring current detection module through the digital isolation communication module. Cx positive The wiring current detection module and the resistance test module are connected to the measurement circuit, the measurement circuit is connected to the control panel, and the control panel is connected to the display and keys.

Preferably, the Cx reverse wiring current detection module, the Cx positive wiring current detection module, the output terminal of the resistance test module, and the CVT low-voltage output terminal are all provided with plug-in ports, and the plug-in ports are installed on the tester housing.

Preferably, the above-mentioned variable frequency power supply adopts an SPWM switching circuit to generate a high-power sine wave regulated output.

Preferably, the above-mentioned control panel is also connected with a printer and a communication interface.

The invention adds the insulation resistance test function on the basis of the dielectric loss tester, and has the dielectric loss multi-channel test, which can measure the dielectric loss, Insulation resistance, absorption ratio and polarization index are also suitable for the measurement of dielectric loss and insulation resistance of power cables. Operators only need one device for a single connection to complete the dielectric loss test and insulation resistance test. While ensuring the accuracy of the test data, the operation time and operation risk are reduced.

The instrument dielectric loss and insulation resistance test of the present invention can be automatically converted. At-a-glance panel operation and LCD display make measurement very convenient and fast.

The output short-circuit current can be measured directly and does not require an on-load measurement for estimation. It has the function of fast measurement time and continuous testing. The implementation function is as follows:

1. With insulation resistance/absorption ratio/polarization index measurement function, with dielectric loss Cx, tgδ measurement function, with CVT transformation ratio measurement function;

2. It has 4-channel positive connection and 1-channel reverse connection function;

3. The wiring of insulation resistance is exactly the same as the wiring for dielectric loss measurement. The shielding method suitable for dielectric loss measurement is also suitable for insulation resistance. When measuring insulation resistance, there is no need to increase any wiring workload;

4. It has positive/reverse wiring, internal/external standard capacitors, internal/external high voltage multiple working modes, integrated structure, and can do various conventional dielectric loss tests without any external auxiliary equipment;

The details are as follows:

(1) The principle structure of the hardware circuit, as shown in Figure 1

The digital high voltage insulation resistance test consists of medium and large scale integrated circuits. It has the characteristics of large output power, high short-circuit current value and multiple output voltage levels, which can meet the testing needs of various equipment on site. Its working principle is as follows:

1. Design of stable and high-power DC high-voltage power supply: The high-voltage power supply output by the internal dielectric loss test will generate DC voltage through AC/DC conversion, and output from the E pole to the L pole through the tested product.

2. High-precision measurement circuit design: The current from the E to the L pole is sent to the measurement system of the dielectric loss meter through A/D conversion. After the CPU completes the calculation, the test results are displayed on the LCD or output by the printer.

3. Measuring range: short-circuit current greater than 100mA; output voltage 250-10000V, measuring resistance 100KΩ-1TΩ

Measurement circuit: Fourier transform, complex arithmetic and other calculations and range switching, frequency conversion power supply control, etc.

Control Panel: Printer, Keyboard, Display and Communication Relay.

Frequency conversion power supply: SPWM switching circuit is used to generate high-power sine wave regulated output.

Step-up transformer: Step-up the output of the variable-frequency power supply to the measurement voltage, the maximum reactive output is 2kVA / 1 minute.

Dielectric loss positive connection test: Cx positive connection current detection: only used for positive connection measurement.

Cx reverse wiring current detection: only for reverse wiring measurement.

Resistance test: Convert the AC high voltage into a DC voltage signal by measuring the control circuit to realize the insulation resistance test function.

Reverse wiring digital isolation communication: use high-speed digital isolation communication circuit to send reverse wiring current signal to the low-voltage side.

After starting the measurement, the high voltage set value is sent to the variable frequency power supply. The variable frequency power supply uses the PID algorithm to slowly adjust the output to the set value. The measurement circuit sends the measured high voltage to the variable frequency power supply to fine-tune the low voltage to achieve accurate high-voltage output. According to the setting of positive/reverse wiring and internal/external standard capacitors, the measuring circuit automatically selects the input and switches the range according to the test current. The measuring circuit uses Fourier transform to filter out the interference, separates the fundamental signal of the signal, and conducts a vector analysis of the standard current and the test current. Operation, the amplitude calculates the capacitance, and the angle difference calculates tgδ. Repeat multiple measurements and select an intermediate result after sorting. When the measurement is over, the measurement circuit sends a step-down command to reduce the voltage of the variable frequency power supply to 0 slowly.

(2) Mainframe software design ideas, as shown in Figure 2.

The main program is divided into three parts: initialization, measurement, display and key processing.

(1) Initialization:

System initialization: related to the hardware interface, including basic interface, display, Bluetooth, etc., and read in the factory parameters, current menu settings and stored data and other information.

Boot screen: The instrument will detect key operations at the same time, and enter as required: factory parameter setting screen (mainly factory calibration data), common setting screen (calendar clock and serial port address, etc.),

(2) Measurement:

AD sampling: start sampling after receiving the synchronization code, responsible for the sampling of voltage and current data, and then obtain phasor data through FFT. Subsequent calculations will select data as required, and unused data will be ignored.

Save data: wait for data here and merge it together. At the same time, the relevant preset parameters (measurement method, Ku,) are saved together.

Average: Used to reduce data fluctuation. The instrument uses the average of 8 measurement data, and the data stabilization time is about 5 seconds.

(3) Display and key processing

Display data: The instrument selects the original data and displays the calculation results according to the requirements (different measurement settings and data screen formats).

Key processing: It includes multiple processing such as setting measurement parameters.

Store and print communication: under the control of keys, enter the store data screen or print data. Communication is to read the received command according to the query mode, and execute the command or send back data according to the requirements of the communication protocol.

Main technical difficulties and solutions

The output voltage of the dielectric loss tester is a stable positive sine wave AC signal, while the insulation resistance test requires a DC voltage test, so the problem of converting the AC voltage to a DC voltage needs to be solved. We use high-power rectification to convert the AC voltage into a stable DC voltage through output filtering. Step-by-step sampling is performed for voltage rectification and filtering, which ensures the stability of the output voltage, and also reduces the heat dissipation problem of the high-power rectifier tube, protects the stability of other components inside the instrument, and ensures the test accuracy of the instrument, as shown in Figure 3.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. It should be included within the protection scope of the present invention, and therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (4)

1. a multifunctional high-voltage electrical equipment insulation testing device, is characterized in that: comprise measuring circuit, frequency conversion power supply, step-up transformer, control panel, Cx reverse wiring current detection module, Cx positive wiring current detection module and resistance test module, The input end of the variable frequency power supply is connected to the main power supply, and the output end is connected to the step-up transformer. The high-voltage output end of the step-up transformer is sequentially connected to the CVT isolation module and the Cx reverse wiring current detection module. terminal, the high-voltage output terminal of the step-up transformer is connected to the measurement circuit through the parallel CVT reverse line and the internal capacitor Cn, and the measurement circuit is connected to the Cx reverse wiring current detection module through the digital isolation communication module, Cx positive wiring current detection module and resistance test The module is connected to the measurement circuit, the measurement circuit is connected to the control panel, and the control panel is connected to the display and keys. 2. a kind of multifunctional high-voltage electrical equipment insulation testing device according to claim 1, is characterized in that: Cx reverse wiring current detection module, Cx positive wiring current detection module and resistance test module output terminal, CVT low-voltage output terminal are all. A plug-in interface is provided, and the plug-in interface is installed on the housing of the tester. 3 . The multifunctional high-voltage electrical equipment insulation testing device according to claim 1 , wherein the variable frequency power supply adopts an SPWM switching circuit to generate a high-power sine wave regulated output. 4 . 4 . The multifunctional high-voltage electrical equipment insulation testing device according to claim 1 , wherein the control panel is further connected with a printer and a communication interface. 5 .

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