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What should be noted when using high-voltage insulation powder coating
source：www.cnjindu.com | Release time：2026年08月08日1、 Storage and preservation (the first line of defense for insulation performance)
Storage environment: Temperature ≤ 25 ℃, relative humidity ≤ 60%, cool and dry warehouse, away from heat sources, steam pipelines, and direct sunlight.
Packaging sealing: original barrel sealed storage; Use within 7 days after opening, and tie the inner bag tightly after each use; Once the powder absorbs moisture and clumps, it is forbidden to directly put it online. Slight clumps need to be sieved through a 140 mesh sieve, while severe clumps can be scrapped directly. Moisture can cause pinholes and poor pressure resistance.
Stacking: Elevate the pallet and keep it off the ground. Do not apply heavy pressure to puncture the inner membrane; It is strictly prohibited to mix with solvents, acids, bases, and water-based paints. Volatile impurities can contaminate the powder and reduce insulation strength.
Do not mix insulation powders of different models and batches, as mixing can alter the dielectric and breakdown properties; If mixing is required, a pressure test must be conducted for verification.
2、 Pre processing of workpieces (most easily overlooked, directly determining pressure resistance and adhesion)
Minor oil stains, water stains, and oxide scales can cause insulation breakpoints and local breakdowns.
Steel parts process: degreasing and degreasing → rust removal (shot blasting) → phosphating → pure water rinsing → drying, no residual salts or cleaning agents are allowed.
Copper busbar and aluminum busbar: degreasing+passivation treatment to remove the oxide layer; Sharp corners and edges must be rounded with a radius of R ≥ 1-2mm. The concentrated electric field at sharp corners can easily lead to partial discharge breakdown of the coating.
Spray as soon as possible after processing to prevent secondary rusting and dust accumulation; The surface is not allowed to have water stains, fingerprints, or dust.
Hangers should be regularly cleaned of old coatings. Excessive powder accumulation on hangers can lead to poor grounding of workpieces, uneven powder application, and insulation defects.
3、 Key points of spray coating construction process
Environmental conditions: Humidity in the spraying workshop is 40-60%; Excessive humidity causes powder to absorb moisture and insulation to decrease. Compressed air must be degreased and dehydrated. The oil-water separator should be drained regularly, and the presence of water and oil in the air path can directly cause shrinkage and pinholes.
Equipment grounding: Spray guns, spray rooms, and workpiece racks must be reliably grounded; Poor grounding can cause static ignition and powder coating. It is strictly prohibited to spray high-voltage insulation powder on live workpieces.
Electrostatic parameters: voltage 60-80kV, spray gun distance from workpiece 15-25cm; voltage should not be too high, as excessive voltage can easily penetrate the forming insulation coating and cause hidden pinhole defects. Reduce the voltage appropriately at complex corner positions to prevent the edges from being too thin.
Coating thickness (the most important among high pressure)
Ordinary low voltage: ≥ 150 μ m; High pressure working conditions are recommended to be ≥ 250-350 μ m; The coating is too thin and the pressure resistance is insufficient; Excessive thickness can lead to bubbles and uneven flow.
Ensure sufficient coating at the corners and grooves, as the corners are prone to thin coating and are high-risk areas for high-voltage breakdown.
Recycling powder: The proportion of high-voltage insulation powder recycling powder should not be too high, as repeated recycling will introduce impurities and reduce insulation performance; It is recommended that the proportion of new powder be ≥ 70% and that coarse impurities be screened out regularly.
4、 Curing baking (insufficient curing, direct insulation scrap)
Strictly follow the curing parameters specified in the powder manufacturer's instructions. Epoxy insulation powder is commonly used: 180-200 ℃, insulation for 10-15 minutes (timing after the workpiece reaches the temperature, not the furnace temperature).
The temperature of the oven should be uniform, and the temperature difference should not be too large; Insufficient curing: incomplete cross-linking, significant decrease in insulation resistance and breakdown strength; Overbaking: The coating becomes brittle and prone to cracking.
It is recommended to increase the temperature gradient of thick coated workpieces to avoid the formation of bubbles and pinholes due to gas explosion inside the coating.
After the solidification is completed and cooled, voltage and insulation resistance tests are conducted, and there is a significant difference in the results between hot and cold state tests.
5、 Finished product testing and usage environment
Spray painted parts must be randomly inspected for voltage breakdown and insulation resistance, not just for appearance; Many pinholes are invisible to the naked eye and can only be detected through electrical testing.
Ordinary epoxy high-voltage insulation powder is not resistant to outdoor ultraviolet radiation and is only suitable for indoor electrical equipment; For outdoor use, organic silicon modified insulation powder should be selected.
Finished workpieces should avoid collision and impact, as even minor cracks in the coating can directly cause the loss of high-voltage insulation capability.
6、 Safe operation
The powder spraying room is a dust explosion-proof area, and open flames and welding are strictly prohibited. All electrical equipment is explosion-proof; Equipped with a dust removal and recovery system to control dust concentration and prevent dust explosion risks.
Operators wear dust masks, goggles, and anti-static work clothes; If the powder enters the eyes, rinse with plenty of water for more than 10 minutes and seek medical attention promptly; Wash the skin with soapy water and do not use solvents to scrub the skin.
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