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Inductive Couplers Explained | Working Principles and Application Examples

Learn about what an inductive coupler is, how it works, and some examples of how they are used with automation.

In this article, we will be talking about inductive couplers. We will explain what an inductive coupler is, how it works, and give some examples of how they are used with automation.

What is an inductive coupler?

An inductive coupler is a device that is used to transmit 24-volt DC power and 24-volt DC input and output signals over an air gap between its two components.

The components of an inductive coupler are called the base and the remote. Not all base components are compatible with all remote components. You will need to make sure your inductive coupler components are designed to work together before connecting any wires.

What-is-an-inductive-coupler

The base is the component that gets connected to 24-volt DC power. The base will also need its input and output signal wires connected in order to work with its remote component.

When the base has 24-volt DC power connected, it creates a magnetic field that when aligned reacts with the remote. The magnetic field is how the 24-volt power and the input and output signals travel over the air gap.

Inductive-coupler-magnetic-field

Inductive couplers have circuitry that changes the magnetic field of the individual input and output signals, so for example, the magnetic field of the green signal wire on the base component can only send or receive signals to or from the green signal wire on the remote component. Inductive couplers can have up to eight individual signals.

Inductive-couplers-individual-signals

The remote component gets connected to the input and output devices, to supply 24-volt power and to send or receive the input or output device signals.

A sensor distribution box can be used here for a cleaner installation. It also makes it easier to install the input and output devices to the remote component because you can just use sensor patch cables instead of connecting the individual sensor cable wires to the remote component cable wires.

Sensor-distribution-box

Different types and installation

Inductive couplers come in many different shapes and sizes. Some are square or rectangular shaped and can be mounted by just bolting them into place.

Inductive couplers mounting

Others are threaded cylindrical shaped and can be mounted by drilling and tapping a hole with the same thread as the inductive coupler and then using a jam nut to lock it into place. There are also brackets you can use to make mounting an inductive coupler easier.

Inductive-couplers-installation

To install an inductive coupler to optimize the 24-volt power transfer from the base component to the remote component, mount the base component and the remote component so that they are aligned.

Inductive-couplers-alignment

After the base and the remote are mounted and aligned, set up the air gap between them per the manufacturer’s installation instructions.

Inductive-coupler-air-gap

Having the base and the remote, out of alignment or too close together or too far apart, will cause the inductive coupler to not operate properly.

Inductive coupler assembling

Inductive couplers applications

Inductive couplers are used in many different ways in automation. Some examples of where an inductive coupler can be used are on a rotating workstation, a workpiece frame, and a robot’s end of arm tooling.

Inductive-couplers-applications

1) Rotating workstation

On the rotating workstation example, let’s say they build two different parts at this workstation, part A and part B. To switch from building on the part A side to the part B side, they just need to turn the workstation table 180 degrees.

When the table is turned to the part A build side, the inductive coupler supply’s the sensor power and will transmit any input or output signals for the part A build side only.

Rotating workstation Inductive coupling

When the table is turned to the part B build side, the inductive coupler supply’s the sensor power and will transmit any input or output signals for the part B build side only.

Sometimes inductive couplers can be used to help limit how many inputs and outputs are needed. Let’s say on the workstation example, build side A and build side B use a part-in-place sensor, a part clamped sensor, and a control valve for the part clamp cylinder.

Instead of each side using its own unique inputs and outputs, the inductive coupler base can be wired to use the same inputs and outputs for both sides. For this to work, both remotes will have to be wired the same and use the same signal wires.

Inductive-coupler-input-output-signals

2) Workpiece frame

A workpiece frame is just a frame used to hold a part while it is being built during production.

Let’s say we are building parts using workpiece frames on an assembly line.At the first workstation, they install the main piece onto the workpiece frame and attach a bracket to this piece.

Workpiece-frame

First, the workpiece frame is put into position and the inductive coupler turns on the sensors. They install the correct parts and the workstation sees that the correct sensors are on before enabling the tool that will connect these parts.

Workpiece frame inductive coupling

When the tool is done connecting the parts together, the workpiece frame is released from the workstation and is ready to go to the next assembly station.

Workpiece frame workstations

If the workpiece frame has sensors installed on it, an inductive coupler can be used instead of a cable, so you don’t have to manually connect and disconnect a cable each time it travels to a new workstation.

Workpiece frame sensor installation

3) Robot’s end of arm tooling

An inductive coupler can be used to power the sensors on a robot’s end of arm tooling. The robot end of arm tooling is the part that gets bolted to the end of the robot arm.

Robot’s-end-of-arm-tooling

Some reasons an inductive coupler might be used on a robot’s end of arm tooling might be the way the robot has to move or if the robot has a tool changer.

If the robot moves in such a way that the sensor cables might get pulled, pinched, or snagged an inductive coupler might be able to correct these issues.

Robot tool changer

A robot tool changer is used when there is one robot doing several different jobs or the robot is doing the same job on several different parts and the end of arm tooling cannot be built to work with all the different jobs or parts.

Robot’s end of arm movement

On simple tool changer setups, one inductive coupler can be used for each tool changer end of arm tooling. If the tool changer needs more than eight input and output signals, multiple inductive couplers can be used.

Multiple-inductive-couplers

Summary

In review, by reading this article you have learned about inductive couplers, that they have two components called the base and the remote, that they transmit 24-volt power and 24-volt input and output signals over an air gap, and that not every base works with every remote.

You also learned some of the ways that inductive couplers are used with automation.

Please let us know if you have any questions about inductive couplers in the comments below and we will get back to you in less than 24 hours.

Got a friend, client, or colleague who could use some of this information? Please share this article.

Adam Stykemain

Adam Stykemain

Automation Engineer

Posted on Aug 9th, 2021

Adam Stykemain

Adam Stykemain

Automation Engineer

Posted on Aug 9th, 2021

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Balluff Inductive Couplers

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