If we look closely at generators, electric motors, and transformers, we’ll notice that their iron cores aren’t made from a single solid piece of metal—but rather from numerous thin silicon steel laminations coated with insulating varnish. Electronic Transformer Insulating Varnish What is its function?

　　Electronic transformer insulation varnish is widely used in AC motors and electrical appliances. After each transformer core laminations are coated with the insulating varnish, they are divided into numerous conductors with very small cross-sectional areas. This significantly increases the resistance of the material, confining eddy currents to narrow, thin layers within the laminations. When magnetic flux passes through these narrow cross-sections of the laminations, the net electromotive force induced in the resulting current loops becomes minimal, while the loop lengths remain relatively long and the overall resistance rises. As a result, eddy current losses—though still present (representing part of the iron loss)—are drastically reduced compared to solid-core designs. Thus, applying electronic transformer insulation varnish not only minimizes eddy current losses but also enhances the efficiency and safety of the transformer, achieving its intended purpose effectively.

　　When a metal block is placed in a time-varying magnetic field or made to move within it, an induced current is generated inside the metal, forming a closed loop—much like the swirling motion of water, which is why these currents are called eddy currents. A high-voltage DC power supply, also known as a DC high-voltage power source, converts AC mains electricity or three-phase power into a DC output capable of delivering several thousand volts or even tens of thousands of volts. Such supplies typically provide outputs ranging from a few hundred watts up to several kilowatts and are designed to maintain either a stable voltage or a steady current. Specialty transformers serve purposes beyond simple AC-to-DC conversion—they can also be used to alter power frequencies, supply rectifiers, power welding equipment, electric furnaces, or even voltage/current transformers. At the heart of these transformers lies a core made from silicon steel laminations. To minimize heat losses caused by eddy currents within the core, the silicon steel sheets, which have a relatively high silicon content, are typically just 0.23 to 0.5 mm thick. Importantly, both sides of these laminations are coated with an insulating varnish, ensuring that individual layers remain electrically isolated from one another. In fact, the insulation layer on electronic transformers is often only a few microns thick. Surrounding the transformer core are coils of wire. When alternating current flows through these coils, the magnetic flux passing through the core continuously fluctuates over time, inducing an electromotive force within the core itself. This, in turn, generates those pesky eddy currents. Unfortunately, these eddy currents not only waste significant amounts of electrical energy but also produce substantial heat, leading to inefficiencies and potential damage to connected devices. In severe cases, the core can even overheat to the point of partial melting, posing a serious risk of "fire" within the transformer. To address this issue of eddy current losses, one effective strategy for manufacturers is to enhance the resistivity of the core materials used in transformer designs.

　　The critical development issue has arrived: How can we increase resistivity?

　　1. The Role of Silicon Steel Sheets

　　Because our thin-sheet materials have very high resistivity (eddy current losses in silicon steel are only 1/5 to 1/4 of those in ordinary steel), we can significantly reduce and minimize eddy current losses.

　　2. The purpose of applying insulating paint

　　Iron cores made from thin silicon steel sheets coated with a thin insulating layer or insulating oxide are widely used in AC motors and electrical devices.