Galvanic isolation is a term used in the field of electrical engineering and describes the avoidance of electrical conduction between two circuits that still need to exchange signals. Simply explained, it is an electronic separation between two conductive objects. These can be, for example, two different circuits. There are several components that can provide galvanic isolation. The most common is a transformer or a transmitter. The coupling mechanism works in this case via a magnetic field.
Galvanic isolation is used in various technical areas. Among others, various components such as transformers, capacitors, optocouplers or relays are affected. There are different possibilities to separate components galvanically. Here, galvanic separation is mainly done by induction, inductance, radiation or by a potential-free contact. Separation by induction is called inductive separation. With inductive isolation, isolating transformers or transformers are required. When using isolating transformers, galvanic isolation between the primary and secondary circuits can be created simultaneously during the transmission of AC voltages. Galvanic isolation by capacitors is called capacitive isolation. In capacitors, electrical isolation works by coupling through an electric field. Capacitors can allow alternating quantities to pass and stop direct quantities due to charge displacement. Galvanic isolation by an optocoupler is called optoelectronic isolation. This type of isolation is mainly used for digital signals. DC voltage signals are thus transmitted via a light line. Here, a transmitting diode conducts the signal to a receiving transistor.
Galvanic isolation is therefore necessary when two circuits with voltage are to interact, but the reference potentials of the voltage are separated.
Galvanic isolation has a wide range of applications. On the one hand, it is used for the safety of electrical toys, all mains-powered extra-low voltages and medical equipment. Furthermore, it is used for metrological instruments, for example for the voltage supply of measuring instruments and its circuit. Furthermore, galvanic isolation is used to prevent hum loops or electromagnetic interference. Finally, galvanic isolation is also required for remote data transmission on high-voltage lines and for protection against electromagnetic pulses. Furthermore, it is used for safety reasons to separate touchable parts of circuits with life-threatening voltages.
Transformers are among the most important components for galvanic isolation. The coupling mechanism here is via magnetic field. The circuits are galvanically separated because the primary winding and the secondary winding of the transformer are not connected with each other, here there is a galvanic decoupling. In autotransformers, on the other hand, there is a galvanic connection because part of the secondary winding is formed from a tap of the primary winding.