Questions for Relays Testers

It is not clear what you are asking. There are relays for all kinds of applications. The problem with high voltages is that some circuits make it difficult for the current to stop flowing when the contacts are separated. Then you have a small lighting storm (or 3 small lightning storms to be exact). When arcing occurs upon opening up the contacts, the temperature of the contacts rises to the point where metal begins to vaporize. That makes for a short life on the contacts as well as a potential for more serious damage.

Frequently magnets are used to suppress the arcing but more than one set of contacts in series also helps to extinguish an arc.
Now that you know this, what exactly are you asking?

Hi Mr. Joe, thank you for your time replying my query. What i am trying to ask is that are:

1. There are relay testers with excess voltage channels for example in Doble they have 6 channels but say i will test a relay specifically an undervoltage function it is obvious that i dont need high voltage output from the relay tester right?

2. Say i will test end to end testing (via gps for synchronization of both test sets) do i need to pursue for high current output?

I am very confuse since i only have some experience in a very low current and low voltage output i am usually testing 50, 51, 27, 59 and starting to test relays with 87 function.

If I understand you correctly, you may have to build your own relay tester. I'm not clear if you are testing relay coils or contacts or both. The science is very different for the two most important parts of the relay.

The metals chosen for contacts varies according to the application. Arcing is a big concern as it pits and eventually destroys the contacts. I've seen relays that melted due to software bugs that caused a lot of heat buildup when the contacts chattered.

The magnetic field in the coil can only provide a certain amount of force and a poorly designed coil can also be a problem. There is an entire branch of electrical engineering devoted only to contact resistance that addresses many of these concerns. But, they are spread far and wide so it may be difficult to find an expert.

You made reference to, "testing 50, 51, 27, 59 and starting to test relays with 87 function" which I assume are classes of relays. I would expect for each class to have a specific set of characteristics per their design, but it is just a guess.

It became clear to me very early in my professional experience that you couldn't just throw any mix of relays together and expect a good result. Over the years, I have debunked automatic test equipment as being unfit due to poor choices for relays.Lastly, what was your meaning about using a gps for synchronization of both sets?I don't understand how a gps would be used unless you are comparing functionality at sea level verses low earth orbit. Perhaps the abbreviation was meant for something else.

Hi Mr. Joe, thank you for your time to answer my questions here.

Hi Mr. Peter, thank you also for the effort to answer here, honestly your answer is somehow clears my doubts with regards to testing relays. And one more thing i admit i am very new to relay testing and i need to learn a lot.

@Mr. Joe, What i've meant for the gps is that for to relay test sets at each end the gps will do the time trigger enabling synchronization of both relay test sets for the end to end testing.

@PeterT Sir what do you mean by this? "Then you may need 6 current sources capable of driving the burden of the relays". What do you mean by driving the burden of the relays is it to surpass or able to attain a certain burden level of the relay itself?

Thank you so much Mr. Joe and PeterT for your efforts in this discussion.

Yes, you are correct. Some of the older electromechanical relays that operate on current have high internal burden, and the test set's current outputs need to have enough VA capability to operate the relay. The newer numerical relays and digital relays don't generally have these problems.

As I said in my first post, it would be well for you to get some training in relay testing, but even more to learn about relay function and operation. For a good free resource, download the GE "Art and Science of Protective Relaying" document at the following link:

GE Art & Science of Relaying

@PeterT I see, so can i assume that since most of the numerical and digital relays today hass less burden requirement can be treat as negligible?

Also i would like to give my appreciation in providing the reference courtesy of GE.

Basically i enjoy this type of discussion, since i can interact with Engineers from around the world.

I think you need to get some additional training in relay testing. You are confusing the varioius types of relays and their particular input current and voltage requirements.

The high current capability test set outputs (with high VA rating) are usually used to test current differential relays. If you are doing a 3-phase test (rather than on individual single-phase relays), then you may need 6 current sources capable of driving the burden of the relays. However, the voltage sources will probably not even be used because current differential relays don't look at the voltage for that function.

High voltage output is usually low VA, so the test set does not need to have high VA capability to drive those inputs. So if you have to provide several hundred VAC to a relay, it is drawing so little current that the total VA is minimal.

For line relay end-to-end testing, you need to provide 3-phase currents and voltages to the relays at each end. That only requires 6 sources at each end - 3 voltage and 3 current. Depending on the magnitude of the secondary currents for the particular fault conditions that you are simulating, you may need high VA current outputs, but it may not be required.

The Doble 6000 series test sets provide plenty of capability to do pretty much all of those tests. For some of the older, high-burden relays where more VA capability is needed, there was a particular model of the F2000 series that had it. I can't remember if it was the F2700 or F2253, or something else.

Anyway, determine your specific requirements, and then get the test set that provides the capabilities you need.

Wait a minute! Are you talking about electro-mechanical devices that use some control signal to cause switching to occur at a different voltage/signal type? Or are you talking about satellite relay stations? There is a very, very big difference.

It wasn't until you mentioned the GPS system that I started to think you were talking about something else. I'm taking GPS to mean Global Positioning System. What are you using for the meaning of GPS?

Lastly, if you are trying to synchronize electro-mechanical relays, even of the same type, I wish you luck. The problem is not the electrical side of things.....it is the mechanical synchronization that will never happen reliably. If you think otherwise, you are in for some major disappointments.

@NotUrOrdinaryJoe, No Sir, my concern is not on how to synchronize EM Relays via the GPS, what i said was to synchronize both test sets (Relay Tester) using gps, OMICRON does this using the state sequencer module, the gps module serves as the trigger for the two test sets so they can issue a signal (in our case the signal was carried by the fiber optic line) at the same time hence being in "sync".

Ahhhh, so then gps must mean "general purpose sync"? I'm sorry that I obviously do not understand the purpose of your tester or the need for fiber optic.

Here I go again, trying to guess what kind of relay you are talking about. It could take me a while to guess which type, out of hundreds, you might be talking about. So, looking at what has been offered so far, including some series dreamed up by some manufacturer, this thing apparently switches fiber optic signals?

Or, perhaps it is not a relay but a repeater that is supposed to fire a pulse down some fiber-optic line? Is there mechanical motion involved in this relay series that you mentioned? What could it be? Can you take a picture of a sample relay? I'm not going to go to Omicron's web page to narrow my guessing.

Oh, and a "state sequencer" could be a lot of things depending on the usage. You won't get much help here unless you can be a lot more specific.