In our life, because of lightning strikes or the instantaneous closure of a switch of a large power station, a current will be generated, which will affect our The electrical equipment will cause great damage. Therefore, we generally use lightning surge generators to simulate this situation, conduct tests, and protect electrical equipment as much as possible. The following is the research and analysis on the lightning surge generator.
1. Features of Lightning Surge Generator>
1. The instrument adopts a color LCD touch screen display, the data is clear and obvious, which is convenient for the operator to operate, and it has a built-in computer Control, realize the intelligent operation of man-machine dialogue, convenient and simple to operate, and bring great convenience to operators;
2. The use of program-controlled high-voltage power supply makes the voltage stable and accurate The current and voltage can be seen on the display;
3. In order to ensure the consistency of the surge waveform, imported non-inductive high-power resistors are used, which greatly enhances the reliability of the test;
4. During the measurement process, the voltage polarity of the instrument is automatically switched between positive and negative, and it can also be switched alternately between positive and negative according to the user's test needs;
5. The entire lightning surge immunity test is stable Using software control, no manual operation is required, which greatly reduces labor consumption, and at the same time avoids operational errors, making the test more accurate and reliable; The setting enhances the flexibility of the instrument and meets the needs of more users;
7. There are current and voltage attenuators inside the instrument, which can be directly connected to the oscilloscope through BNC, so that the waveform can be observed intuitively;
8. The instrument is equipped with a computer interface, which can implement remote control, and can also choose measurement and control system software to meet the needs of more users;
Second, the simulated situation of the lightning surge generator test is mainly to simulate various situations caused by indirect lightning strikes>
1. When lightning strikes the external line, a large amount of current flows into the external line or grounding resistance, thus generating an interference voltage.
2. Indirect lightning strikes (such as lightning strikes between clouds or within clouds) are externalVoltage and current are induced on the line.
3. Lightning strikes objects adjacent to the line, and a electromagnetic field is established around it, which induces voltage on the external line.
4. The lightning strikes the adjacent ground, and the interference introduced when the ground current passes through the public grounding system. In addition to simulating lightning strikes, it also simulates the interference introduced by switching actions in substations and other occasions (voltage transients caused by switch switching), such as:
1), the interference generated when the main power system is switched (such as capacitors group switching)
2), the same power grid, the interference when some small switches near the equipment jump 3), switching thyristor equipment with resonant lines
4), each systemic faults, such as short circuits and arcing faults between equipment grounding networks or grounding systems
Third, lightning surge generator precautions>
1. The test personnel must be trained and learned before they can operate the equipment, and they should read the equipment instruction manual before operation;
2. Pay attention to the model specification and wiring method of the prototype before starting up and shutting down;
3. The instrument should be well grounded;
4. When setting the high voltage, the panel indication value should not exceed 4.5kV, and do not touch the interference line with your hands;
5. The instrument cannot be inverted to prevent vibration;
6 , In order to ensure the comparability and repeatability of the test, the test configuration must be standardized;
Fourth, the source of the surge voltage generated by the lightning strike>
1. The direct lightning strike acts on External circuit, the injected large current flows through the grounding resistance or external circuit impedance to generate voltage
2. Indirect lightning strikes that generate induced voltage and current> on the inner and outer conductors of the building
3. The current of the lightning that discharges directly to the ground nearby is coupled to the common ground loop of the equipment grounding system. When the protective device operates, the voltage and current may change rapidly and may be coupled to the internal circuit