Insulation is one of the most important design areas in a high frequency transformer. It affects safety, certification, winding structure, leakage inductance, parasitic capacitance, thermal behavior, and manufacturing repeatability. If insulation requirements are defined after the first sample, the transformer may need a structural redesign rather than a small adjustment.
BaoHui Tech manufactures high frequency transformers, power transformers, inductors, filters, and custom magnetic components for switching power supplies, inverters, UPS systems, chargers, and industrial electronics. For custom high frequency transformer projects, insulation requirements should be part of the first RFQ.
Start with the safety requirement
The design team should define whether the transformer needs functional insulation, basic insulation, supplementary insulation, or reinforced insulation. This depends on the application, working voltage, user access, product standard, and target market. A transformer used inside an isolated auxiliary supply may have different requirements from a transformer used in EV charging or industrial grid-connected equipment.
When the safety requirement is known early, the transformer manufacturer can select a suitable bobbin, winding arrangement, tape system, sleeving, wire type, and pin layout.
Creepage and clearance affect mechanical design
Creepage is the distance along an insulating surface. Clearance is the distance through air. Both are shaped by working voltage, pollution degree, insulation category, material group, and safety standard. In a compact high frequency transformer, these distances often control the final size.
Trying to reduce transformer height or footprint without considering creepage and clearance can create a design that is electrically attractive but difficult to certify or manufacture.
Triple-insulated wire can simplify some structures
Triple-insulated wire is often used when reinforced insulation is required in a compact transformer. It can reduce the need for certain margin tape structures and may help fit the winding into a smaller window. However, it also affects cost, winding process, termination, and thermal behavior.
The decision should be based on safety requirements, current level, available bobbin space, and production process capability. It is not simply a premium material choice.
Hipot testing validates dielectric strength
Hipot testing is a necessary production check for many isolated transformers. It verifies that the insulation can withstand a specified voltage for a defined time. The test voltage and duration should match the product requirement, not a generic factory habit.
Passing hipot is important, but it does not replace correct creepage, clearance, material selection, and thermal design. A complete insulation system must satisfy both geometry and dielectric strength.
Insulation choices affect electrical performance
More spacing between windings may improve isolation but increase leakage inductance. Interleaving may reduce leakage but increase capacitance between primary and secondary windings. Shielding may reduce common-mode noise but adds complexity and must be insulated correctly.
This is why insulation should be designed together with efficiency, EMI, and thermal targets. A safe transformer still has to work well in the actual converter.
FAQ
What insulation information should be sent to a transformer manufacturer?
Send the working voltage, isolation voltage, safety standard, required insulation class, creepage and clearance expectations, product application, and target market.
Can BaoHui Tech design reinforced insulation transformers?
Yes. BaoHui Tech supports custom transformer design with insulation structures based on customer safety, electrical, mechanical, and production requirements.
Good insulation design is not only about passing a test. It is about building a transformer structure that is safe, repeatable, and compatible with the converter performance.