inductive proximity detectors life expectancy

Hello everyone,

It has been 10 month since I replaced the swinging gate limit mechanical switches by inductive proximity sensors from OMCH. The ones I used are NO, NPN, p/n LJ12A3-4-Z/BX .I bought five pieces: four for the two leaves of the gate: open limit and close limit and one spare. What I find now with astonishment is that all 4 used parts exhibit an abnormally high Vout low voltage. The two pictures show Vout low of a used part vs the spare one which has not been used. I had some email / whatsapp exchanges with the director of International Trade Department of OMCH and facing the two pictures she stated that 10 month is about the life expectancy of their detectors, because "the electronic parts, the use frequency is more, the life is much shorter" Note that even if for some reason the behaviour of the analog part is deteriorating with time, it does not explain why should the digital output stage degrade. Honestly I think she was joking but yet thought it'd be useful to share this story here. The drawing of the circuit is the one describes here w/o the diode.

Any good quality inductive proximity switch should last pretty much forever, as long as it is not being damaged by environmental or electrical events.

Industrial machines use them in large quantities and its not unusual to see originals that are several decades old.

Is there any chance that they are experiencing voltage spikes?

No I don't think there were spikes. They were powered by a separate supply (not the one of the wing gate controller which drives the 220V motors) However I have not checked the power and output with t&m equipment

Last dialogue with OMCH: my questions in green answers in blue

So, I think now everything is perfectly clear: after 10 month of operation in the setup of the drawing "proximity detector limit switch (4)" the Vout low is pretty much higher than with a new part. So my questions:

Do you confirm that this can happen with your parts

or, do you think that the 4 misbehaving parts are from a failed batch

or do you think there was something wrong in the way they've been used as shown in above mentioned drawing?



Dear friend, normally, the proximity sensor, the life is around 10 months. I think it is normal

Is that so?? It's hard to believe! Usually electronic parts has life expectancy greater than a human

the electronic parts, the use frequency is more, the life is much shorter

Thank you for this information. This is really important data that I'll share with the electronic engineering community.

I'd class their response as bovine excreta, to put it as politely as I can.
They are making excuses for poor quality somewhere, either over-run components or plain low grade stuff.

This is an example or reliability data for some Omron inductive proximity sensors; the mean time to failure is in the range 1000 to 2000 YEARS...