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Date：07-13-2026
Factory tests for high-voltage wall bushings are split into two core categories: Routine Factory Tests (100% inspection for every finished unit) and Type Tests (design verification for each new product model). All tests strictly follow international standards IEC 60137, IEEE C57.19.00 and relevant regional grid specifications, aiming to eliminate hidden defects in raw materials, manufacturing, assembly and sealing before delivery.
These tests screen production flaws for each finished product and serve as the delivery acceptance basis.
Workers fully check the exterior appearance, structural integrity and dimensional tolerances.
The most fundamental dielectric performance test for condenser-type wall bushings (RIP, RIS, OIP structures).
Conducted together with capacitance measurement to detect tiny internal voids, air gaps or insulation defects invisible to naked eyes.
Verifies basic AC insulation strength of the bushing’s internal insulation system.
Critical for oil-filled, gas-filled and resin-impregnated wall bushings to prevent moisture ingress.
DC megohmmeter test before high-voltage dielectric tests to judge overall insulation cleanliness and damp status.
Spot-check thread tightness of conductor nuts, grounding bolt torque and flange fitting tightness; ensure all fasteners meet specified torque standards to avoid loose contact heat generation on site.
Type tests validate the whole design’s long-term service reliability, not executed on every finished bushing, but required to obtain product certification.
1. Wet Power-Frequency Withstand Test: Simulate rainy outdoor operating conditions to verify external shed pollution flashover resistance.
2. Lightning Impulse (BIL) & Switching Impulse (SIL) Withstand Test: Simulate lightning surges and grid switching overvoltage; test full-wave, chopped-wave impulse voltage endurance.
3. Temperature Rise Test: Energize the bushing under rated continuous current for dozens of hours; record temperature distribution of conductor, flange and insulation surface to confirm no overheating and qualified thermal stability.
4. Short-Time Thermal Current Withstand Test: Apply rated short-circuit current for specified seconds; check no permanent deformation, melting or insulation carbonization after test.
5. Cantilever Mechanical Load Test: Apply lateral force on the bushing’s outer end to simulate cable pulling and wind load; confirm flange and insulator do not crack or deform under maximum allowable bending load.
6. Thermal Cycling Test: Alternate high-low temperature cycles to simulate seasonal climate change; assess resistance to thermal expansion & contraction cracks inside insulation and bonding layers.
7. Pollution & UV Aging Test (for polymer wall bushings): Salt-fog pollution test and ultraviolet weathering test to prove anti-pollution and anti-aging performance of external silicone rubber sheds.
8. Gas Evolution Test: Detect harmful gas precipitation inside insulation under long electrical stress, applicable for resin-impregnated dry-type bushings.
1. Raw material incoming sampling test: Porcelain insulator bending strength, silicone rubber tensile & hydrophobicity test, insulating paper moisture content check.
2. Coating adhesion test: Verify anti-corrosion coating on metal flanges will not peel off.
3. Packaging vibration simulation test (batch sampling): Confirm the bushing survives transportation vibration without internal damage.
All routine factory tests act as the last quality gate before shipment to eliminate individual product defects, while type tests fully validate the rationality of structural design, material matching and process flow. Only wall bushings passing all required factory tests can be attached with a qualified certificate and delivered to customers.
Address：No.27, Binhai South 3 road, Yueqing Economic Development Zone, Wenzhou City,Zhejiang Province,China.
