Testing electromechanical relays - Voltage requested to the current am

[521AB]

What is the voltage we still require today at a test set (current output) for being able to test the most difficult electromechanical relay?
I am out of mechanical relays since years, but in the US there are a lot of them.
Do you have please some data in terms of VA, or max voltage requested to the current amplifiers?

Any real data from the field?
Thanks for any input!

 

[itsmoked]

There are countless thousands of different "electromechanical relays". There is NO standard for this vast field. If you are talking about a specific type of electromechanical relay then maybe someone can offer up a suggestion.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[GTstartup]

I think he is refering to protective relays. But I am not sure if I understand the question.

Do you need the power consumption of the test set or the output parameters? For example a typical test set might be able to supply 150V AC and 50A but not at the same time. This would cover most relays

 

[521AB]

Thanks for posting!
yes, I was talking about protective relays. Sorry..

150 VAC?
So much?
I have hard to believe that a protection relay must be energized with 150 V AC (RMS I understand), on the current circuit. But I may be wrong.
I have the feeling that 80 V AC RMS if not 40 V AC are enough, but unfortunately i´this is just a feeling for the moment.
If you have some electromechanical protection relay in your substations (probably those with the rotating disc), please try to remember me and verify what is the voltage that is applied to the rely when you test it.

 

[GTstartup]

OK let's take a generator overvoltage relay for example. Nominal secondary voltage 115V AC set at 110% That's 121 VAC so OK you might get away with 130V AC

 

[521AB]

Wait,
I am talking about CURRENT INJECTION.

What I have in mind is a directional earth-fault relay, because some colleagues state that they need more than 100 V RMS in the current circuit in order to test it. But they never told me the relay type.. and never showed me the relay, so I believe the troubles are somewhere else.

 

[dpc]

You need to check the burden at the appropriate tap and add a little for lead resistance. This will help you determine how much voltage you'll need to develop the necessary current. Of course it's going to depend on the tap setting. Burden is highest at the lowest tap setting.

Relay instruction books are available on-line from ABB for the CO-x series of overcurrent relays and from GE for the IAC and IFC series.

It can be done with a good, high-power audio amplifier in some cases.

You could just check the specs on relay test sets. Any of them sold in the US should be adequate to drive common electro-mechanical relays.

 

[GTstartup]

Sorry, i just reread your post. You are only talking about the voltage required on the current output. This depends on the relay burden. I wouldn't worry too much about the voltage as the relay impedances are in the range of fractions of an Ohm.

 

[521AB]

The problem is that the output stage (transistors or whatever) of the current amplifiers "do not like" voltage. They may give you even 40 A continuously, but maybe maximum 50 V, and as all of you say, the voltage depends on the load in which the current flow.
Current amplifiers with 40 V rms are much less expensive than current amplifier that manage a voltage of 150 V rms, and I am not sure I want to really spend those money..

Putting in series current amplifiers (to increase the total voltage) is not the best idea.
To my opinion, 40 volts RMS are more than enough for most of the electromechanical relays, but some colleagues are here talking about 150 V rms, and this figure popped also up even in this thread.

Has anybody really SEEN 150 volts RMS applied on the current circuit of the electromechanical relay?

 

[GTstartup]

No, that would destroy the relay

 

[GTstartup]

Assuming the test set didn't trip which it would

 

[dpc]

Why do you think you need 150V?

 

[GTstartup]

Well, you live and learn. Evidently there are some ground fault relays out there that have very high VA testing requirements.

http://www.doble.com/content/products/F6150_Brochure_1-2008.pdf

 

[oldfieldguy]

The MultiAmp SR-76 was pretty much the standard for testing electromechanical relays for years. It had taps for various current ranges, and If I remember correctly, the 0-8 amp range would put out 150 volts.

Some electromechanical relays can be rather difficult to test with the newer solid-state test sets.

old field guy

 

[capuchi]

Try inquiring from Advanced Test Equipment Corp. or AVO Multi-Amp Corp. The first is a equipment rental company while the second is the leading (I guess) Protective Relay Test Equipment manufacturer. They have test sets that comes in low voltage but high current output.

Hope it helps.

capuchi

 

[pwrengrds]

The only relays I have had trouble testing with an Omicron 156 was a Generator Differential. They require about 15 volts to activate the relay and push current. What I generally did was to use the voltage output and put a current meter in series with the voltage to get around it. Even the higher current settings (100 amps secondary) generally don't require more than that, if they do I go to an MS-2.

 

[521AB]

What I am trying to do, is to find out -technically- if there is need of such high voltage or not, for the current outputs (it is also called compliance voltage).
The fact that some test sets are shooting such big output values, does not always mean they are doing right. A lot of things in our world have been done because "it has always been done like that", or just because some competitors have done it.

To my opinion, people are trying to test relays connected in series from the end of the series, and for this you might need high compliance voltage (the sum of all relays in series). This test would be a wrong test, because first you should perform a relay test, independent from the system in which it is going
o work, then you can perform a system test, to verify all the connections, but you do not need to test again the relay itself, You may just need to inject a higher fault current, not requiring such high voltage.

That's what I am trying to discover.