The principle of an isolating transformer is the same as that of a normal transformer. They all use the principle of electromagnetic induction. Isolation transformers generally refer to 1:1 transformers. Because the secondary is not connected to the ground. There is no potential difference between any of the secondary lines and ground. Safe to use. Often used as a maintenance power source.
The isolation transformer is not all 1:1 transformer. The power supply that controls the transformer and the tube equipment is also an isolation transformer. Power supplies such as tube amplifiers, tube radios, and oscilloscopes and lathe control transformers are isolation transformers. For example, a 1 to 1 isolation transformer is commonly used for safe maintenance of color TVs. Isolation transformers are used more and are also used in air conditioners.
Generally, although there is an isolation circuit between the original and secondary windings of the transformer, in the case of a high frequency, the capacitance between the two windings still causes static interference between the circuits on both sides. In order to avoid such interference, the primary and secondary windings of the isolation transformer are generally placed on different cores to reduce the capacitance between the two; also, the primary and secondary windings are placed concentrically, but are placed between the windings. Electrostatic shielding for high immunity to interference.
Electrostatic shielding is to place a piece of copper or non-magnetic conductive paper that is not closed between the primary and secondary windings, called the shielding layer. Copper or non-magnetic conductive paper is connected to the outer casing with wires. Sometimes in order to achieve a better shielding effect, a shielded casing is also covered in the entire transformer. The lead terminal of the winding is also shielded to prevent other external electromagnetic interference. In this way, only the magnetic coupling between the primary and secondary windings is mainly left, and the equivalent distributed capacitance between them can be less than 0.01 pF, thereby greatly reducing the capacitance current between the primary and secondary windings, and effectively suppressing the power supply and other circuits. Various interferences.