What are the applications of voltage withstand testers in the power industry
Voltage withstand tester (also known as high voltage tester or high-voltage tester) is a key instrument used in the power industry to test the insulation performance of electrical equipment. Its core function is to apply a test voltage higher than the rated voltage of the equipment, evaluate the withstand capacity of insulation materials or structures under high voltage, and prevent leakage, short
Voltage withstand tester (also known as high voltage tester or high-voltage tester) is a key instrument used in the power industry to test the insulation performance of electrical equipment. Its core function is to apply a test voltage higher than the rated voltage of the equipment, evaluate the withstand capacity of insulation materials or structures under high voltage, and prevent leakage, short circuit or safety accidents caused by insulation breakdown. The applications in the power industry mainly cover the following scenarios:
1、 Insulation testing of power generation equipment
Power generation equipment is the source of the power system, and its insulation performance directly affects the safety of power generation. Voltage withstand testers can be used for factory inspection, regular maintenance, or troubleshooting of various types of power generation equipment
Generator: Test the insulation strength between the stator winding, rotor winding, and casing, as well as the insulation performance between turns and phases of the winding. For example, synchronous generators need to undergo a power frequency withstand voltage test after major repairs to verify whether the insulation has aged due to long-term operation, moisture, or mechanical damage.
Steam turbine/water turbine auxiliary electrical system: Test the insulation of control cabinets, cables, sensors and other components that are matched with the main engine to avoid local insulation failure affecting the stable operation of the generator set.
Battery pack: Test the insulation of individual battery cells and connections between groups to prevent DC system faults caused by leakage (especially in DC operating power sources of hydropower stations and thermal power plants).
2、 Voltage withstand test of power transmission and transformation equipment
The transmission and transformation equipment is responsible for power transmission and voltage conversion tasks, and the insulation reliability in high-voltage environments is crucial
transformer:
Conduct power frequency withstand voltage tests between windings and between windings and iron core/shell to test the performance of insulation paper and insulation oil (such as oil immersed transformers that require oil quality analysis, withstand voltage tests can verify whether insulation degradation is caused by impurities or moisture in the oil).
Conduct impulse withstand voltage test on the epoxy resin insulation layer of dry-type transformers to simulate the insulation withstand capability under extreme working conditions such as lightning overvoltage.
High voltage switchgear: including circuit breakers, isolating switches, load switches, etc., test the insulation strength between their breaks, phases, and to ground. For example, GIS (gas insulated switchgear) needs to pass SF ₆ gas insulation withstand voltage test to ensure sealing performance and insulation level.
Transformer: Insulation testing between the primary and secondary windings of voltage and current transformers, as well as between the windings and the casing, to prevent damage to the secondary side equipment or electric shock to personnel due to insulation breakdown.
Transmission lines: Conduct voltage withstand tests on overhead lines and cable lines (such as DC voltage withstand tests on cables) to detect whether the insulation layer is damaged, damp, or aged (especially after cable laying, before operation, and during regular maintenance).
3、 Insulation verification of distribution equipment and terminal appliances
The distribution system is directly connected to the user, and the insulation performance of the equipment is related to electrical safety:
Distribution cabinet/distribution box: Test the phase to phase and ground insulation of internal busbars, circuit breakers, contactors, and other components to avoid insulation reduction caused by dust and moisture, which can lead to short circuits.
Power cables: In addition to transmission cables, distribution cables (such as low-voltage cables and control cables) need to undergo withstand voltage testing before and after installation to identify insulation damage (such as compression and scratches) that may occur during the construction process.
Electric motor: Conduct a voltage withstand test on the stator winding of asynchronous and synchronous motors to detect whether the insulation has failed due to overload, moisture, or winding aging (for example, water pump motors and fan motors must pass the test after major repairs before they can be put back into operation).
4、 Construction and acceptance process of power engineering
Before the new equipment is put into operation: After installation, all electrical equipment (such as transformers, switchgear, cables, etc.) must undergo a voltage withstand test to verify whether the insulation is damaged during transportation and installation, ensuring compliance with the "Electrical Equipment Handover Test Standards for Electrical Installation Engineering".
After line maintenance: After emergency repairs or modifications (such as replacing insulators and joints), the insulation performance of overhead lines or cables must be confirmed through withstand voltage tests to avoid recurrence of faults.
Preventive testing: According to the regulations of the power industry (such as DL/T 596-2021 "Preventive Testing Regulations for Power Equipment"), regular voltage withstand tests (such as once a year or every three years) should be conducted on equipment in operation to detect potential problems such as insulation aging and moisture in advance and prevent sudden power outages.
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