Galvanic isolation

Galvanic isolation is a principle of isolating functional sections of electrical systems, thus preventing the movement of charge-carrying particles from one section to another, i.e. there is no electric current directly from one section to the next. Energy or information can still be exchanged between the sections by other means, e.g. capacitance, induction or electromagnetic waves, or by optical, acoustic or mechanical means.

Galvanic isolation is used in situations where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor.Galvanic isolation is also used for safety considerations, preventing accidental current from reaching the ground (the building floor) through a person's body.

Overview

• Transformers couple by magnetic flux. Primary and secondary side have no electrical connection. The isolation voltage (industry standard) is measured in kilovolt. The same applies to transductors.
• Optocouplers transmit information by light waves. The sender (light source) and receiver (photosensitive device) are electrically isolated by plastic.
• Capacitors couple by capacitance. Capacitors couple only the AC component of the signal while DC is blocked. As it is possible for some capacitors to fail short circuit, there are special ratings for capacitors used for isolation, such as "Class Y"......
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