Galvanic Isolation

Galvanic isolation is a term in electrical engineering that describes the avoidance of electrical conduction between two circuits that still need to exchange signals. Simply put, it is an electronic separation between two conductive objects, which could be two different circuits, for example. There are various components that can enable galvanic isolation. The most well-known of these is a transformer or an isolating transformer. The coupling mechanism works through a magnetic field.

Operation of Galvanic Isolation

Galvanic isolation is used in various technical fields. Among other things, different components such as transformers,

capacitors, optocouplers, or relays are involved. There are several ways to achieve galvanic isolation of components. Primarily, isolation is achieved through induction, influence, radiation, or by a potential-free contact.

Inductive isolation is achieved through induction. In inductive isolation, isolation transformers or isolating transformers are required. When using isolation transformers, a galvanic separation between the primary and secondary circuits can be created during the transmission of alternating voltages.

Galvanic isolation through capacitors is called capacitive isolation. In capacitors, electrical isolation works through coupling via an electric field. Capacitors can allow alternating signals to pass through due to charge shifts while blocking direct current signals.

Galvanic isolation via an optocoupler is called optoelectronic isolation. This type of isolation is mainly used for digital signals. Direct current signals are transmitted through light transmission. In this process, a light-emitting diode sends the signal to a receiving transistor.

When is galvanic isolation necessary?

Galvanic isolation is necessary when two circuits with voltage need to interact, but their reference potentials are separate.

Applications of galvanic isolation

Galvanic isolation has a wide range of applications. On one hand, it is used for safety in electrical toys, all low-voltage devices powered by the grid, and medical equipment. Furthermore, it is used in measuring instruments, for example, in the power supply of measuring devices and their circuits. Additionally, galvanic isolation is employed to prevent ground loops or electromagnetic interference. Ultimately, galvanic isolation is also required in data transmission over high-voltage lines and for protection against electromagnetic pulses. Moreover, it is used for safety reasons to isolate touchable parts from circuits with life-threatening voltages.

Galvanic isolation in transformers

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