Ruibian (Jiangsu) Electric Power Co., Ltd. is one of the leading manufacturers and suppliers of vacuum varnish impregnation isolation transformer in China. With abundant experience, our factory offer high quality products made in China with competitive price. Welcome to contact us for pricelist.
Materials & Processes
VPI impregnation process: Pre-drying and dehumidification of the workpiece, cooling, placement in a vacuum to remove air and volatiles, then using the weight of the varnish and capillary action, combined with dry compressed air or inert gas pressure, to rapidly penetrate and fill the insulation structure.
Insulation system: Class H (180°C) or Class R (220°C) UL-certified insulation system.
Core: High-permeability cold-rolled silicon steel, stepped lap stacking.
Windings: High-quality oxygen-free copper wire, fully cured after VPI treatment.
Enclosure: Cold-rolled steel or stainless steel, with protection rating customized as required.
Key Advantages
Superior insulation performance: After VPI treatment, the product has excellent insulation properties, low partial discharge, and strong lightning impulse withstand capability.
High mechanical strength: The cured resin forms an integral structure, preventing loosening during operation and avoiding short-circuit insulation failures.
Good moisture resistance: The varnish fills all micro-voids and gaps, significantly improving moisture protection.
Reduced temperature rise: Eliminates internal air gaps that would otherwise create hot spots 20°C above average temperature.
Extended service life: Comprehensive insulation protection significantly prolongs transformer life.
Application Scenarios
Medical equipment
Dedicated isolation power supplies for CT scanners, MRI systems, X-ray machines.
01
Industrial automation
Isolation for PLC control systems, input isolation for variable frequency drives.
02
Data centers
Isolation for server power supplies, UPS matching.
03
Telecom base stations
Power isolation and noise suppression.
04
Laboratories
Precision instrument power supply, electrical isolation.
05
Packaging & Transport
Packaging
Moisture-proof wooden crates or cartons with cushioning materials inside.
Transport
Avoid severe vibration and tilting to prevent resin cracking.
Storage
Store in dry, ventilated environment with relative humidity ≤85%.
FAQ
Q1: What is the difference between VPI and epoxy resin casting?
A: VPI uses vacuum pressure to impregnate varnish into the coil and then cures it – lower cost and suitable for batch production. Epoxy resin casting uses a mold to fully cast the coil – more complete resin filling, lower partial discharge, but higher cost.
Q2: Does a VPI isolation transformer require regular maintenance?
A: The VPI process makes the coil integral and highly moisture-resistant, so it is essentially maintenance-free. Only periodic checks of terminal tightening and surface cleaning are needed.
Q3: Can VPI transformers operate in humid environments?
A: Yes. The VPI process significantly improves moisture resistance, making them suitable for high-humidity environments. However, long-term outdoor exposure still requires an appropriate protection-rated enclosure.
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