What is 4-20mA galvanic isolator?

What is galvanic isolation?

A method of isolating functional parts of electrical systems in order to stop current flow is known as galvanic isolation; no direct conduction channel is allowed. Other methods, such as capacitive, inductive, radiative, optical, acoustic, or mechanical ones, can still be used to transfer energy or information between the sections.

When two or more electrical circuits need to communicate yet have potential differences between their grounds, galvanic isolation is utilised. By preventing undesired current from moving between two devices that share a ground conductor, it effectively breaks ground loops. Galvanic isolation is another safety measure that guards against unintentional electric shocks.

What are the different types of galvanic isolation?

There are several sorts of isolation techniques, and choosing the best approach mostly depends on the type of isolation, the resist capacity, the requirements for the application, and the cost.

Techniques for Isolating Signals

Signal isolation techniques include using optoisolators and Hall Effect sensors.


When a signal must flow between two ground potentials, an optoisolator is utilised. It is a photoresponsive transistor that turns on when its internal light-emitting diode is turned on. This diode produces signal-lane light that doesn’t breach the ground potentials’ isolation barrier.

A Hall Effect Sensor

An inductor may convey information magnetically over a small space using hall effect sensors. Unlike optoisolators, they don’t have a stable source of light, and in contrast to the transformer-based method, they don’t require DC balancing.

Power Isolation Techniques

The use of transformers and capacitors is one way of power isolation.


The most used type of isolation in transformers is galvanic isolation. Transformers have a wide range of uses, with voltage stepping up and down being one of the most popular. Although the main and secondary windings of the transformer are unconnected, it may step-down the voltage from high to low AC voltage without compromising galvanic isolation.


The capacitor’s primary job is to prevent direct current while allowing alternating current to pass. These parts link two circuits with ac signals of various voltages. It could short-circuit and cause harm depending on the circumstances. Producing this isolation is done primarily to guard against the possibility of a current source malfunction.

What is 4-20mA galvanic isolator?

In a circuit for transmitting an analogue 0(4)-20mA signal, this device guarantees safe galvanic isolation between the input, output, and supply. Ground loops are removed, noise levels are decreased, and transient signals are blocked via galvanic isolation.

There are several industrial automation uses for this device. It is perfect for reducing mistakes brought on by noise and signal interference, safeguarding delicate machinery like a PLC. Both 0-20 mA and 4-20 mA signals may be transmitted with this type.

Assume that your processing unit is 500 meters from a temperature sensor that uses a 4-20 mA current loop and is located in the field. The temperature transmitter must be installed close to the sensor for the measured value to be sent via a 4-20 mA analogue signal to the processing unit. The risk of a potential impact to the processing unit exists, and the wire is vulnerable to interferences and transient signals. A galvanic isolator need to be installed next to the processing unit to stop this from happening.

A 4-20mA galvanic isolator is a device used in industrial applications to isolate and protect sensitive electronic equipment from electrical noise and interference. It works by electrically isolating two circuits, while allowing the transfer of an analog current signal between them.

A galvanic isolator provides electrical isolation between the two circuits, which helps to prevent electrical noise and interference from disrupting the signal. It typically uses optical or magnetic isolation to transfer the signal between the two circuits, which eliminates the need for a direct electrical connection.

4-20mA galvanic isolator is an important tool for ensuring reliable and accurate communication between industrial control devices, and can help to improve the performance and safety of industrial processes.