Check all Digital Inputs and Outputs


Check all Digital Inputs and Outputs

Topic Progress:

Digital inputs and outputs are failure points in modern relaying that cannot be tested via the relay’s self-tests. An output contact can be fused closed or be frozen open. We can test the outputs by pulsing the relay contacts to make sure that they change state.

Digital inputs are often damaged by incorrect connections, so it is important to use as much of the installed wiring as we can. Always try to operate the end-device connected to a relay whenever possible. Applying your own circuit to test in-service inputs should be a last resort.

It is important that we test all the inputs and outputs during an acceptance test to prove that the manufacturer sent us a functioning relay. Better to find out now that there is a problem, instead of later when the relay is in service.

Watch these videos to see how to test the digital inputs and outputs of protective relays from these manufacturers:

Schweitzer Engineering Laboratories, Inc.

Beckwith Electric Co., Inc.

General Electric / Multilin


ABB Relays

Don’t see your relay in this series? Leave a comment below and we’ll see if we can get a demonstration unit and add a video for that test-set.

Click “Mark Complete” below after watching the video so you can keep track of your progress.

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Kindly show any ABB & Seimens Digital input/outpout functions of relays. Please

Chris Werstiuk (Administrator) November 25, 2016 at 7:58 am

Siemens is in post production right now, everyone should get an email in a couple of weeks listing all the new content.

Chris Werstiuk (Administrator) December 4, 2016 at 4:31 pm

The video for Siemens relays is online now.

Thanks for the suggestion.

Chris Werstiuk (Administrator) March 27, 2017 at 9:08 am

An ABB relay video is now online

how to do this test connecting Omnicron test set?

Chris Werstiuk (Administrator) July 24, 2017 at 9:53 am

The easiest way to perform this test is with a multi-meter monitoring ohms in beep mode. I can;t really show that in a video, so I used a test-set.

If you wanted to do it manually as shown with Omicron Test Universe, simply use Quick CMC.

If you want to document it, you would create a State Sequence as shown in the logic testing section of the course.

Using an Omicron to test the inputs do I use the state sequencer to cycle through binary outputs or move the leads from input to input?

Chris Werstiuk (Administrator) April 13, 2018 at 7:59 am

It’s a personal preference. You could check everything in QuickCMC and write a note stating you checked them all, or you could truly document every input and output with a state sequencer.

Joshua Liuga Suiramo February 8, 2021 at 9:37 am


Appreciate demonstration of connection of omicron test set to Siemens as done with GE relay SR.


Chris Werstiuk (Administrator) February 8, 2021 at 10:39 am

We hope to get Siemens relays added this year.

I have to find some first.

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