The selection of power frequency withstand voltage test equipment should follow the principles of “parameter matching, scene adaptation, and compliance with standards”. It is necessary to scientifically choose intelligent or manual devices based on the parameters of the test sample, test frequency, safety requirements, budget, and other factors to avoid “over-selection” or “under-selection” and ensure the smooth progress of the test work.
I. Core Parameter Determination (Applicable to All Types of Devices)
The prerequisite for selecting power frequency withstand voltage test equipment is to clarify the core parameters of the test requirements. Based on the specifications of the test sample and industry standards, determine the voltage level and capacity of the test equipment, which is the basis for selection.
(1) Voltage Level Selection
The high-voltage rated voltage of the test transformer should be greater than the test voltage of the test sample and reserve a margin of 20% to avoid inaccurate test results due to insufficient voltage. The specific reference is as follows:
For 10kV electrical equipment (such as 10kV switch cabinets, distribution transformers), the test voltage is usually 42kV, and a test device with a rated high voltage of 50kV should be selected;
For 35kV electrical equipment (such as 35kV cables, transformers), the test voltage is usually 95kV, and a test device with a rated high voltage of 100kV should be selected;
For 110kV and above electrical equipment, the test voltage is usually 265kV or above, and an intelligent device with the corresponding high voltage level should be selected (manual devices cannot meet the requirements of high voltage and high precision).
(2) Capacity Selection
The rated capacity of the test equipment should meet the requirement of “capacity ≥ test voltage (kV) × test current (A)”. The test current can be calculated by the formula: test current ≈ 2πfCU × 10⁻³ (where f = 50Hz, C is the capacitance of the test sample, unit pF; U is the test voltage, unit kV). Based on the actual scene, the commonly used capacity grades are as follows:
For 10kV distribution network equipment: commonly used 5kVA/50kV, 10kVA/50kV;
For 35kV equipment: commonly used 20kVA/100kV, 30kVA/100kV;
For 110kV and above equipment: commonly used 50kVA/200kV, 100kVA/250kV.
(3) Power Supply Selection
For devices with a capacity of ≤5kVA, a 220V AC power supply can be used; for devices with a capacity of ≥5kVA, a 380V AC power supply should be used to ensure the stable operation of the device.
II. Selection Decision between Intelligent and Manual Devices
After determining the core parameters, the selection of intelligent or manual devices should be made based on the test frequency, safety requirements, data requirements, budget, and other factors. The specific decision-making logic is as follows:
(1) Scenarios where intelligent devices should be preferred
High test frequency (≥5 test samples per day), batch testing, to improve test efficiency;
Test data needs to be archived and standardized reports generated, meeting the requirements of preventive tests in the power system and product certification;
Test sample voltage level ≥ 35kV, expensive test samples (such as transformers, GIS equipment), with high safety and measurement accuracy requirements;
Few operators, to reduce human error and improve test standardization;
Long-term use, sufficient budget, and emphasis on the expandability and intelligence level of the equipment, requiring integration with the laboratory management system.
(2) Scenarios where manual devices should be preferred
Low test frequency (≤10 test samples per month), occasional use, no need for batch testing;
Test sample voltage level ≤ 10kV, simple structure, only need to determine insulation pass/fail, no need for high-precision measurement and data storage;
Limited budget, pursuing low cost, no need for extended functions;
Experienced operators, capable of proficient manual operation, and the test scene is temporary emergency or field work;
Teaching demonstrations, basic tests, only need to show the test principle and basic operation.
III. Additional Selection Considerations
(1) Selection of Test Transformer Type (1) Oil-immersed test transformers feature high voltage, large capacity and good stability, making them suitable for laboratory and fixed-site use; dry-type or gas-filled test transformers are lightweight, leak-proof, moisture-resistant and suitable for on-site mobile and field operation scenarios.
(2) Protection Function Selection
For intelligent devices, it is recommended to choose models with overvoltage, overcurrent, flashover, zero position interlock and door interlock functions to enhance safety and reliability. Manual devices should at least have overcurrent protection, zero position indication and emergency stop functions.
(3) Interface and Expandability Selection
For intelligent devices, models with USB, RS485 and Ethernet interfaces should be selected based on actual needs to facilitate data export and remote control. If multiple types of tests are required, models that support insulation resistance and dielectric loss test expansion should be chosen.
(4) Standard Selection
Ensure that the device complies with industry standards such as GB/T 16927.1-2018 and DL/T 596-2021, and comes with a product qualification certificate and test report to ensure the validity of the test results.
Post time: Apr-15-2026