---
title: Galvanically Isolated Barriers
description: "## Galvanically Isolated Barriers Devices which overcome the limitations of zener barrier are called **isolation** interfaces. Typically, the isolation required may be achieved by using transformers, opto-couplers and/or relays. These **galvanically isolated barriers** are barriers which allow transference of energy…"
url: "https://www.eicstech.com/kb/intrinsic-safety-ex-i/basics-on-galvanic-isolation/"
updated: "2022-06-01"
category: Explosion Proof Basics / Intrinsic Safety (Ex i)
---

# Galvanically Isolated Barriers

## Galvanically Isolated Barriers

Devices which overcome the limitations of zener barrier are called **isolation** interfaces.

Typically, the isolation required may be achieved by using transformers, opto-couplers and/or relays.

These **galvanically isolated barriers** are barriers which allow transference of energy from one side to the other, **without any direct wired connection** between the power source on the one side and the hazardous area terminals on the other.

The galvanic isolator must prevent high voltage break-through into the hazardous area, and limit the voltage and current to the hazardous area.

## Examples of Galvanic Isolation

In this example, isolation between the hazardous and safe areas is achieved by means of a high integrity transformer and relay.*The voltage & current limiting circuitry is not shown.*

![galvanic isolation](https://www.eicstech.com/wp-content/uploads/2022/06/galvanic-isolation-example.png)

## Opto-coupler isolation

In an opto-isolator, light or infrared emitted from the LED falls onto the phototransistor, transmitting the signal from hazardous to safe area.

![opto coupler isolation](https://www.eicstech.com/wp-content/uploads/2022/06/opto-coupler-isolation.png)

Note that the galvanic isolator incorporates a resistor/zener circuit to do the actual energy limiting, in the same way as in a discrete zener barrier.

Many types of galvanic isolator are available to meet specific instrumentation requirements.

![opto coupler isolation 2](https://www.eicstech.com/wp-content/uploads/2022/06/opto-coupler-isolation-2.png)

## Earthing of Galvanic units

The major advantage of **galvanic isolation barrier** that an **intrinsically safe earth is not required**.

They can be used in earth-free instrumentations (where a single earth fault would not cause a hazard) or where the hazardous area measuring device is earthed via the plant.