The 10 kV zinc oxide arrester is a core protective device for overvoltage protection in power systems, and its operating condition directly affects the insulation safety and stable operation of various electrical equipment within the system. Conducting standardized and regulated preventive tests enables accurate detection of hidden defects such as moisture ingress, material aging, and internal insulation damage in arrester discs. This paper systematically organizes the key test items, standardized operational procedures, and compliance evaluation criteria for 10 kV zinc oxide arresters, strictly following the “Preventive Test Regulations for Electric Power Equipment” (DL/T 596) and the “Standard for Handover Tests of Electrical Equipment in Electrical Installation Projects” (GB 50150).
I. Insulation Resistance Test
This test serves as a fundamental diagnostic tool for assessing the arrester’s condition, enabling rapid identification of internal moisture, severe surface contamination on porcelain sleeves, or through-type damage to the main body, providing essential baseline data for subsequent specialized tests.
The test is conducted using a 2500 V megohmmeter. During wiring, connect the high-voltage terminal of the megohmmeter to the high-voltage electrode of the arrester, and reliably ground the other terminal to the equipment base or grounding electrode. To minimize interference from leakage current along the porcelain sleeve surface, install a shielding ring on the clean, dry outer surface of the porcelain sleeve. After applying voltage and allowing stabilization, record the insulation resistance value at the 1-minute mark as the valid test result.
Compliance Criteria: The insulation resistance of a 10 kV zinc oxide arrester must not be less than 1000 MΩ. Additionally, compared with historical test data from previous operations, there should be no significant downward trend. If the measured value fails to meet this standard or shows substantial degradation, further specialized tests should be performed to comprehensively assess potential equipment faults.
II. Measurement of DC 1 mA Reference Voltage (U₁ₘₐ) and Leakage Current at 0.75 Times Reference Voltage
This test is a critical specialized assessment for evaluating the degree of disc aging and moisture ingress in zinc oxide arresters. Measured values directly reflect the deterioration of the arrester’s nonlinear resistive characteristics and serve as a key indicator for assessing operational reliability.
(1) Test Equipment and Preparations
Use a high-voltage DC generator for testing. Prior to testing, thoroughly wipe the arrester’s exterior to remove dust, stains, moisture, and other contaminants, ensuring a clean and dry surface to avoid external environmental influences on measurement accuracy.
(2) Standardized Operational Procedure
During the test, gradually and uniformly increase the test voltage while continuously monitoring the microammeter reading. When the leakage current precisely reaches 1 mA, immediately record the corresponding voltage value—this is the DC 1 mA reference voltage (U₁ₘₐ). Then quickly reduce the test voltage to 0.75 times U₁ₘₐ. Once voltage and current stabilize, accurately read and record the leakage current at this point.
(3) Compliance Criteria
1. DC 1 mA Reference Voltage (U₁ₘₐ): The measured value must be compared against the manufacturer’s specifications or initial commissioning benchmark. Deviation must not exceed ±5%. If the value exceeds this tolerance, it indicates significant degradation of the varistor’s resistive characteristics.
2. Leakage Current at 0.75 × U₁ₘₐ: The measured value must not exceed 50 μA. An abnormally high reading suggests possible internal moisture ingress or deteriorated paths within the arrester discs, indicating potential fault risks.
At the end of the test, follow strict safety procedures: use a dedicated discharge rod to fully discharge the high-voltage terminal of the arrester, confirm that no residual voltage remains, ensure reliable grounding, and only then disconnect the test connections.
III. Discharge Counter Operation Check
For 10 kV zinc oxide arresters equipped with discharge counters, regular verification of counter reliability is required to ensure accurate recording of lightning strikes and overvoltage events during operation, thereby supporting effective data for equipment status tracking and fault analysis.
Use a dedicated discharge counter tester to apply a standard simulated impulse current to the counter. Repeat this process 3 to 5 times consecutively, observing throughout whether the counter pointer swings or displays digital counts correctly. Under normal operating conditions, the counter should accurately increment with each impact. If any abnormalities such as failure to operate, jamming, counting jumps, or lack of response occur, the root cause must be immediately investigated and repaired to ensure the integrity of the equipment’s monitoring function.
IV. Key Considerations for Test Implementation
1. Safety Management: Safety must be the top priority throughout high-voltage testing operations. Protective barriers should be installed at the test site, prominent warning signs posted, and a dedicated supervisor assigned to monitor the entire process. Unauthorized personnel must be strictly prohibited from entering the work area to prevent safety risks associated with high-voltage operations.
2. Wiring Standards: All high-voltage test leads must be kept short and straight, maintained at a safe distance from grounded objects, and shielded cables should be used whenever possible to effectively minimize interference from stray currents, ensuring accurate and reliable test data.
3. Environmental Corrections: Ambient temperature and humidity significantly affect arrester test results. Environmental temperature and relative humidity must be precisely recorded throughout the test. When necessary, measured data should be properly corrected according to standards. Under normal conditions, a 10°C change in ambient temperature corresponds to approximately a 1% variation in U₁ₘₐ values. Tests should be conducted under favorable weather conditions, with equipment surface temperature not below 5°C and relative humidity preferably controlled within 80%.
4. Testing Schedule: Periodic tests must be strictly carried out in accordance with industry regulations. Routine preventive testing is required annually, with special focused inspections mandated prior to thunderstorm seasons. Additional specialized tests are required during initial commissioning, after severe lightning strikes, or when abnormal alarms occur, to comprehensively ensure grid safety during flood seasons and daily operations.
Post time: Aug-01-2026