How many millions of switching cycles can expect from relay output?

Hello Everyone,

I have a question related to relay outputs. I have implemented signing LED outputs via relay output with 2Hz maximum switching frequency. I am aware that it would be better to implement it with transistor output, but now I don't want to change all the logo modules if it is not needed.

I've found some technical information in LOGO Manual in paragraph "Switching capacity and service life of the contacts with ohmic loading" (p. 336) There's a graph but it begins only from 2A, but the signing LED I control consumes only 18mA. I don't know that in case of such ampere value how many millions of switching cycles I can expect from relay output. Can I take it as infinite?

Could you tell it?

Thank you in advanced,

Zanor

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Split from Amperage output relay Logo.

Hi,

basically your relay should operate unlimites, but there is also a mechanical lifetime.

From my understandning if the lowes load is 2A, then the specific mechanical litetime is at 2A.

But this is not everything you should care. Relais also have a min. current. For LOGO! relais you can find this also in the LOGO! manual. 

For LOGO! the lowest recomended load is 100mA.

So it may happen, that the relay contact doesn't close because of this very low load.

If you controll LED lamps including electronic in side, than take care of the inrush current. It can be 1000 timne higher then the normal current.

Hope this helps