What is electrical isolation?
The so-called electrical isolation is the electrical isolation of the power supply and the electrical circuit, that is, the electrical branch circuit is isolated from the entire electrical system, making it an isolated, independent ungrounded safety system in order to prevent the occurrence of indirect electric shock hazard in the case of exposed conductor fault electrification. To implement electrical isolation, the following conditions must be met:
(1) of each branch circuit using an isolation transformer, this transformer voltage withstand test, higher than the ordinary transformer, should comply with the Ⅱ level electrical products (double insulation or reinforced insulation) requirement, also can be used with isolation transformer winding insulation performance is equal.
The so-called electrical isolation means that there is no direct electrical connection between the two circuits. That is, the two circuits are insulated from each other. It is also necessary to ensure that the two circuits maintain the relationship of energy transmission.
The circuits connected to the first and second sides of a common double-winding transformer are insulated from each other. Therefore, it can be said that the circuit connected by one or two sides of the double-winding transformer is in an electrical isolation state. The principle of isolation is the working principle of transformer and the principle of using the law of electromagnetic induction. When the transformer is in operation, after the primary winding is supplied with alternating current, the alternating flux will be generated in its core, and the alternating flux will induce the electromotive force in the primary and secondary winding. The secondary winding can provide ac voltage to the secondary circuit after induction of electromotive force, when the secondary winding with load after the current flow, will have an impact on the magnetic circuit flux, so as to cause the primary winding current change. Although there is no direct electrical connection between the primary and secondary windings of the transformer, the electrical energy from the primary winding can be transferred to the secondary winding through the flux change in its magnetic circuit. This is the working principle of the transformer, and it is also the principle of electrical isolation between the secondary windings.