Lifetime of relay Siemens 3ZX1012-0RH11-1AA1 1

[SA07]

Hi

Can you plz confirm the lifetime of the relay? (Number of operations)
I have googled the data sheet. It is not available even on Siemens website. It seems it is replaced with new version. Relay was installed in 2006.

 

[SA07]

Our Power plant was operating. The FD fan stopped. So the Boiler stopped and the Power Plant stopped.

The relay is with a colleague. I will check it when I resume work.

 

[RedSnake]

If the drawing you posted 15 Apr 21 06:27 is another then the first one, you need to change the name otherwise I can only get the same drawing twice.

For the relay I would first take a way the RC suppressor and ohm measure the coil to see if it is OK .
Then I would ohm measure the RC-suppressor or if you have a capacitor measurement instrument I would use that as long as it is not 0 ohms or endless it’s probably OK.
But if it is 0 ohm the CJ3 should have tripped.
If this is OK I would put the RC- suppressor back and connect 230V AC to the contacts 13-14 and a switch to the A1-A2 so I could turn the relay on and of and measure the voltage over the contacts it should be 0 V AC when pulled and make test 10-20 times to check if it is ok and if that is OK .
I would take the relay apart and look at the contacts.
I still thinks it is highly unlikely that it is the contacts that are bad with so few on/offs.
We have a machine with Siemens relays that are 43 years old, we maybe have changed 10 of those relays in 30 years but it’s 110 AC.

What hapens is that you get a arc between the contacts when the relay falls.
How long the arc will burn depends on if it is DC current or AC current, with the same current the DC arc will burn until the airgap is large enough to “brake” it .
But for AC it will either burn until the airgap is large enough or when the sinus wave goes over the 0 current/voltage, which usually happens quicker.
The varistor in the the coil of -KMG1 will help putting it out.
That is why a contact with AC over it doesn’t get burnt as fast as a DC one.
And when the contacts have been burned to much it welds the contacts together and the relay will not fall when the coil isn’t powered any more.
It can also not get good enough contact when pulling.
But that happening on a already pulled relay, hmm of course everything can happen sooner or later.

Best Regards A



“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[SA07]

Thanks RedSnake

 

[RedSnake]

Another question.
How big are the consequences when this happens?
It might influence what kind of solution that should be implemented.
And how much money that someone is prepared to put in to it.
If a better maintenance plan is enough or if some backup solution should be put in place.

Best Regards A


“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein