Same as the principle of general transformer, the isolation transformer apply the theory of electromagnetic. The isolation transformer generally refers to the 1:1transformer.
Not all isolation transformers are the 1:1 transformer. Control power transformers and tube equipment is also isolation transformer. Such as tube amplifiers, tube radios, and oscilloscopes and lathe control power transformers are isolation transformers. Commonly used for security maintenance, such as color TV sets 1: 1 transformer.
Commonly isolation transformer is known as safety transformer, and it is generally used to isolate the city electricity network maintenance equipment and other impurities.
Why do you use isolation transformers? First, understand our country's power supply system: the supply of low-voltage power supply system users, in general, three-phase four-wire system, neutral grounding, popular point is that the wires to the homes of local residents, one is relative to the line (FireWire), where the other root is the zero line. When the body hit bottom, the heat would cause the current through the body, and the earth constitutes a loop, causing an electric shock hazard. If use the isolation transformer, it will be safer, because the primary and secondary through magnetic exchange energy, there is no physical hardware connection, even if human contact with electric objects, leaving the electric parts of the potential for low potential, will not cause electric shock hazard. Note two points when you use the isolation transformers:
1, the secondary end of isolation transformer can not be grounded at both ends;
2, people can not touch both of the secondary ends at the same time, or there is risk of electric shock.