Precision vacuum epoxy potted PCB power transformers engineered for high dielectric isolation, extreme thermal stability, and fail-safe industrial reliability.
Custom Footprints & Low Profile
From 0.35VA to 50VA, low no-load current consumption and UL 94 V-0 flame-retardant epoxy encapsulation tailored to your board height limits.
4,200Vrms Dielectric Test
100% automated inspection: LCR bridge, impulse winding surge, DC low-resistance, and complete aging verification before dispatch.
Bubble-free UL 94 V-0 flame retardant resin prevents corona discharge and eliminates humidity penetration.
Two-chamber split-bobbin construction ensures robust galvanic safety and high creepage distances.
Designed with calculated internal impedance to prevent thermal runaway even during perpetual output shorts.
Custom pin mappings, dual primary/secondary taps, low profile heights, and private-label laser marking.
Why elite electronics hardware designers insist on potted linear magnetics in critical operating environments
In an era dominated by high-density switch-mode power supplies (SMPS), the Mini Encapsulated Transformer remains the gold standard for applications where absolute electromagnetic compatibility (EMC) silence, ultimate galvanic isolation, low standby degradation, and decades of maintenance-free operation are paramount. Manufactured by encasing precision wound copper coils and silicon steel laminations within high-grade thermoplastic bobbins, followed by deep vacuum casting with thermosetting epoxy resin, these components create an impervious barrier against ambient contaminants, physical shocks, and high moisture vapor levels.
Unlike open-frame EI laminated transformers, a vacuum-encapsulated transformer eliminates microscopic voids where partial discharges take place. Under high electrical stress, unresolved micro-voids in unencapsulated windings generate corona effects, accelerating dielectric breakdown and causing early field failures. Shaanxi Zelqo Power Co., Ltd. resolves this structural weakness through strict dual-stage automated vacuum degasification and pressure injection cycles, achieving a certified dielectric withstand voltage of up to 4,200Vrms between primary and secondary circuits.
Mini encapsulated linear transformers operate on fundamental 50/60Hz line frequencies without high-frequency harmonic spikes, eliminating switching noise that disrupts high-precision ADC sensors, instrumentation amplifiers, and metering circuits.
The thermal conductivity of our epoxy potting compound is over four times greater than ambient air. Internal heat generated inside copper windings is conducted smoothly to the outer casing surface, lowering hotspot temperatures by up to 25% under full-load conditions.
Hardware procurement professionals managing smart grid projects, industrial PLCs, smart home automation, and medical monitoring systems require magnetics that comply strictly with IEC/EN 61558-2-6 and UL 5085 safety directives. Shaanxi Zelqo Power Co., Ltd. delivers engineered mini encapsulated solutions tested across extensive thermal cycles (-40°C to +125°C), ensuring long-term parameter stability.
Engineered to fit standard grid pitches with low hum, minimal temperature rise, and unconditional short-circuit options
Our flagship mini encapsulated component for IoT nodes, auxiliary power boards, and smart meters. Available with dual 115V or single 230V inputs, featuring inherently short-circuit-proof safety characteristics and an exceptionally compact 32.5mm × 27.5mm footprint.
Specifically engineered for slim-enclosure 1U server racks, security panels, and compact DIN-rail housings. The dual-core UI geometry allows extremely low vertical profiles under 22mm while maintaining maximum creepage and clearance distances.
Designed for audiophile preamps, sensitive ECG medical monitors, and laboratory test gear requiring virtual silence from inductive hum.
Rugged design engineered for industrial heating, ventilation, air-conditioning (HVAC), elevator control panels, and factory PLC controllers.
Specialized encapsulated ignition and sensor isolation transformers with epoxy-cured dielectric barrier handling transients up to 10kV.
Where magnetic component design and OEM supply chain architectures are heading over the next 5 to 10 years
Global regulatory mandates, including the EU ErP Directive and US DoE Level VI standards, are compelling procurement engineers to target sub-0.15W no-load power losses. This has accelerated sourcing demand for high-permeability, ultra-thin grain-oriented electrical steel (CRGO) cores in mini encapsulated transformers to lower core hysteresis and eddy-current losses.
As edge-computing modules and DIN-rail systems become denser, bulky cubic transformers are giving way to flat UI formats. Low-profile designs allow surface integration into shallow junction boxes and wall switches without compromising 8mm creepage and clearance distances between mains and extra-low voltage (SELV) pins.
Automotive sub-assemblies and solar micro-inverter control boards operate under severe ambient temperatures exceeding 85°C. Next-generation transformer specifications demand Class F (155°C) and Class H (180°C) certified epoxy compounds alongside non-toxic, halogen-free, bio-derived resin matrixes that support corporate ESG initiatives.
Shaanxi Zelqo Power Co., Ltd. provides drop-in compatible designs with customized pin arrangements to match obsolete European transformer catalog numbers.
Shaanxi Zelqo Power Co., Ltd. couples vertical manufacturing control with Intertek on-site facility verification
Computerized tension control ensures exact turn-counts and eliminates wire crossover strain, preventing inter-turn short circuits before encapsulation.
Two-chamber progressive degassing and vacuum potting remove micro-bubbles down to <5mbar, achieving zero micro-discharge at continuous high voltages.
Every transformer undergoes LCR bridge tests, impulse winding surge tests, DC resistance screening, and 4.2kV hi-pot testing prior to carton packing.
Rapid ODM engineering generates calculated electrical models, samples, and compliance-ready benchmark units within 7 business days.
Verified real-world tooling, winding equipment, and testing bays inside our production facility
Every step adheres strictly to ISO9001-certified processes, preventing defective sub-assemblies from entering vacuum potting stations.
Metrology and compliance validation: 100% of finished lots are checked for insulation resistance (>100MΩ at 500VDC), hi-pot breakdown voltage, and accurate turns ratio verification.
Standard mechanical and electrical parameters for common mini encapsulated transformers
| Core Series | Power Rating (VA) | Dimensions L×W×H (mm) | Ambient Temp (ta) | Short Circuit Mode | Weight | Inquiry |
|---|---|---|---|---|---|---|
| EI 30/10.5 | 0.35VA – 0.6VA | 32.5 × 27.5 × 15.2 | ta 70°C/B | Inherently Safe | ~ 45g | Get a Quote |
| EI 30/12.5 | 1.0VA – 1.5VA | 32.5 × 27.5 × 18.0 | ta 70°C/B | Inherently Safe | ~ 68g | Get a Quote |
| EI 30/15.5 | 1.8VA – 2.4VA | 32.5 × 27.5 × 22.0 | ta 70°C/B | Inherently Safe | ~ 82g | Get a Quote |
| EI 30/18.0 | 2.6VA – 2.8VA | 32.5 × 27.5 × 24.5 | ta 70°C/B | Inherently Safe | ~ 95g | Get a Quote |
| EI 38/13.6 | 3.5VA – 4.5VA | 41.0 × 35.0 × 28.0 | ta 40°C/B | Non-Inherently | ~ 150g | Get a Quote |
| UI 30/7.5 (Flat) | 3.0VA – 4.0VA | 53.0 × 44.0 × 17.5 | ta 70°C/F | Non-Inherently | ~ 130g | Get a Quote |
| UI 39/10.2 (Flat) | 10.0VA – 14.0VA | 68.0 × 57.0 × 22.0 | ta 40°C/B | Non-Inherently | ~ 290g | Get a Quote |
Custom primary/secondary voltage combinations and bespoke pin configurations are developed on request without tooling charges.
Detailed engineering answers addressing common questions regarding mini encapsulated transformers
Avoid communication delays with non-technical middlemen. When you connect with Shaanxi Zelqo Power Co., Ltd., your custom mini encapsulated transformer RFQ is reviewed directly by qualified power electronics engineers.