It is mainly reflected in the ability of the arrester to absorb various lightning overvoltages, power frequency transient overvoltages, and switching overvoltages. The current carrying capacity of the zinc oxide arrester fully meets or even exceeds the national standard requirements. Indicators such as line discharge level, energy absorption capacity, 4/10 nanosecond high current impulse withstand, and 2ms square wave current carrying capacity have reached the domestic leading level.
2. Excellent protection characteristics
Zinc oxide arresters are electrical products used to protect various electrical equipment in power systems from overvoltage damage, with good protection performance. Because the nonlinear volt-ampere characteristics of zinc oxide valve plates are excellent, only a few hundred microamperes of current pass through under normal working voltage, making it easy to design a gapless structure, which gives it the characteristics of good protection performance, light weight, and small size. When overvoltage intrudes, the current flowing through the valve plate increases rapidly, while limiting the amplitude of the overvoltage and releasing the energy of the overvoltage. After that, the zinc oxide valve plate returns to a high resistance state, allowing the power system to operate normally.
3. Good sealing performance
The arrester components adopt high-quality composite outer sheath with good aging resistance and air tightness. Measures such as controlling the compression amount of the sealing ring and adding sealing adhesive are adopted. The ceramic outer sheath is used as a sealing material to ensure reliable sealing and stable performance of the arrester.
4. Mechanical performance
Mainly consider the following three factors:
(1) Earthquake force borne;
(2) Maximum wind pressure acting on the arrester;
(3) The maximum allowable tension of the conductor borne by the top of the arrester.
5. Good anti-pollution performance
Gapless zinc oxide arresters have high anti-pollution performance.
The creepage distance ratio levels specified by national standards are:
Level II Medium pollution area: creepage distance ratio 20mm/kV
Level III Heavy pollution area: creepage distance ratio 25mm/kV
Level IV Extra heavy pollution area: creepage distance ratio 31mm/kV
6. High operational reliability
The reliability of long-term operation depends on the quality of the product and whether the product selection is reasonable. The factors affecting its product quality mainly include the following three aspects:
(1) The rationality of the overall structure of the arrester;
(2) The volt-ampere characteristics and aging resistance of the zinc oxide valve plate;
(3) The sealing performance of the arrester.
7. Power frequency withstand capability
Due to various reasons in the power system such as single-phase grounding, long line capacitance effect, and load shedding, power frequency voltage rise or transient overvoltage with high amplitude may occur. The arrester has the ability to withstand a certain power frequency voltage rise within a certain period of time.
Operating Steps
Turn on the power switch, and the startup interface appears on the screen.
After a few seconds, the main menu (as shown in the figure) appears as follows. The specific operation instructions of the main menu are as follows:
l Line number: Press the "Function" key to move the cursor to "Line number", press "OK" to enter; press the "Function" key to select the position to adjust, and a small cursor will appear at this position; press the "Increase" and "Decrease" keys to select, after all positions are adjusted, press the "OK" key.
l PT ratio: Press the "Function" key to move the cursor to "PT ratio", press "OK" to enter; press the "Function" key to select the position to adjust, and a small cursor will appear at this position; then press the "Increase" and "Decrease" keys to select, after the position adjustment is completed, press the "OK" key.
l Test phase sequence: Press the "Function" key to move the cursor to "Test phase sequence", press "OK" to enter; press the "Function" key to select the position to adjust, and a small cursor will appear at this position; press the "Increase" and "Decrease" keys to select, after the position adjustment is completed, press the "OK" key. Among them, A, B, C represent single-phase measurement, and X represents three-phase simultaneous measurement.
l Compensation angle: The adjustment method is the same as above. Generally, the influence of interphase interference is about 2° to 5°. Due to the difficulty in accurately calculating the interference amount, hard compensation is generally not recommended, but it is set to 0.0°. According to the regulations, the data change trend over a period of time can be compared longitudinally. If you need to adjust the side phase correction angle, please refer to the relevant chapters in "Measurement Principle" later. If three-phase simultaneous measurement is selected, the angle is automatically compensated.
l Date: The adjustment method is the same as above. Use the "Function" key to select the item to adjust: year, month, day, hour, minute, second, and use the "Increase" and "Decrease" keys to adjust. After all adjustments are completed, press the "OK" key.
l Mode: Press "OK" to switch among wired, induction, and wireless modes.
l View: Press the "Function" key on the keyboard to move the cursor to "View", press "OK" to enter (as shown in Figure 6); press the "Increase", "Decrease", and "Function" keys to select the data to view, and press the "OK" key to display that set of data.
