Principle of Isolation Transformer

Principle of Isolation Transformer

The principle of isolation transformer is the same as that of ordinary transformer. They all use the principle of electromagnetic induction. Isolation transformers generally refer to 1:1 transformers. Because the secondary is disjointed. There is no potential difference between any of the secondary wires and the ground. Safe to use. Commonly used as a maintenance power supply.

Isolation transformers are not all 1:1 transformers. The power supply for the control transformer and tube equipment is also an isolation transformer. Power supplies such as tube amplifiers, tube radios and oscilloscopes and lathe control transformers are isolating transformers. For example, 1:1 isolation transformers are commonly used for safe maintenance of color TVS. Isolation transformers are used more often and are also used in air conditioning.

In general, although the primary and secondary windings of the transformer also have the role of isolating the circuit, in the case of high frequency, the capacitance between the two windings will still cause electrostatic interference between the two sides of the circuit. In order to avoid this interference, the primary and secondary windings of the isolation transformer are generally placed on different core columns to reduce the capacitance between them. There are also concentric placement of primary and secondary windings, but electrostatic shielding is added between windings to obtain high anti-interference characteristics.

Electrostatic shielding is to set a non-closed copper sheet or non-magnetic conductive paper between the primary and secondary windings, which is called the shielding layer. Copper sheets or non-magnetic conductive paper are wired to the housing. Sometimes in order to achieve better shielding effect, a shielding shell is also covered in the entire transformer. The lead wire terminal of the winding is also shielded to prevent other external electromagnetic interference. In this way, there is only residual magnetic coupling between the primary and secondary windings, and the equivalent distributed capacitance between the primary and secondary windings can be less than 0.01pF, thus greatly reducing the capacitive current between the primary and secondary windings, and effectively suppressing various interference from the power supply and other circuits.