Galvanic isolation

Galvanic isolation is a term used in the field of electrical engineering and describes the avoidance of electrical conduction between two circuits that still have to exchange signals. In simple terms, it is an electronic separation between two conductive objects. These can be two different circuits, for example. There are various components that can provide electrical isolation. The best known of these is a transformer or a transformer. The coupling mechanism works via a magnetic field.

How galvanic isolation works

Galvanic isolation is used in various technical areas. Among other things, various components such as transformers, capacitors, optocouplers or relays are affected. There are various ways of galvanically isolating components. Induction, induction, radiation or a potential-free contact are the main methods of electrical isolation.
Induction isolation is called inductive isolation. Isolating transformers or transformers are required for inductive isolation. When isolating transformers are used, galvanic isolation can be created between the primary and secondary circuits during the transmission of AC voltages.
Capacitive isolation is used for galvanic isolation using capacitors. With capacitors, electrical isolation works by means of coupling through an electric field. Capacitors can allow alternating quantities to pass through and stop direct quantities due to charge shifts.
Electrical isolation using an optocoupler is called optoelectronic isolation. This type of isolation is mainly used for digital signals. Direct voltage signals are therefore transmitted via a light line. A transmitting diode transmits the signal to a receiving transistor.

When is galvanic isolation necessary?

Galvanic isolation is therefore necessary if two circuits are to interact with voltage, but the reference potentials of the voltage are separated.

Areas of application for galvanic separation

Galvanic isolation has a wide range of applications. On the one hand, it is used for the safety of electrical toys, all mains-powered low voltages and medical devices. It is also used in measuring instruments, for example in the power supply of measuring devices and their circuits. Furthermore, galvanic isolation is used to prevent ripple loops or electromagnetic interference. Finally, galvanic isolation is also required for long-distance data transmission on high-voltage lines and to protect against electromagnetic pulses. It is also used for safety reasons to separate touchable parts from circuits with life-threatening voltages.

Galvanic isolation for transformers

Transformers are among the most important components in galvanic isolation. The coupling mechanism here is via a magnetic field. The circuits are galvanically isolated because the primary winding and the secondary winding of the transformer are not connected to each other, in this case there is galvanic decoupling. In contrast, autotransformers have a galvanic connection, as part of the secondary winding is created from a tap of the primary winding.