Pepi switch on/off operational life?

[RidgPaul]

Hi all

Am wondering what sort of life you can expect from Pepi switches, with very low current.....thinking on/off operations...and how reliable are they?

Paul

 

[jmarko]

Hi, Paul!

What is Pepi Switch? Please describe application.
Usually, mechanical switches have mechanical live expectancy cca. one third to twice more than electrical (for example, specific switch for 240V/2A withstands 100.000 ON/OFF operations actually switching 2A current and 130.000 or more operations with only mechanical trip - no current). Live expectancy of switch can span from few hundreds to few 100.000 operations (depends of construction; the better, the more expensive!). Switch for small currents must be dedicated or with gold plated contacts; non-dedicated switch can build significant resistance between contacts (also thermal and other electrical noise can affect signal, if currents are in range lower than mA!).

For small signals, reed switches are best solution; they have life expectancty up to few millions operations and contact resistance down to few 10 milliohms.
You can trigger them with permanent magnet, like as at bicycle speed counter or switch for detecting if window is open (for house alarms).

Best regards, Jmarko

 

[jmarko]

Hi, Paul!

sorry for previous message; please check also
next sites:

http://www.pepiusa.com/

,

http://www.creasefield.co.uk/prod_ther.html.

Best regards, Jmarko

 

[RidgPaul]

These switches have gold contacts, but what i am interested in is someone who has practical experience, as in have done a production run of equipment using them and tracked the reliability over time(where they are operated many times).

I build remote radio monitoring equipment, and have a choice between a mechanical switch with set temperature characteristics, or a FET switching/thermistor arrangement. This is for a cooling fan arrangement in the equipment box, the fan brings in external air at ambient temperature as the box internal temperature rises up between 45-50 degrees in top of box.

The reason i would even consider a Pepi switch, is that they require no calibration, and i avoid circuit design that required calibration, where i can.

Anyway think i will go with the FET/thermistor arrangement, i am guessing the thermister cold to hot swing(steepness of temp co.) is great enough that the component tolerance spread wont be a problem, and that maybe fixed component values will do(no pots).

If i do have to have a pot for the high temp threshold i will make sure that the value just covers the minimum range of adjustment needed, so that failure of the pot will still result in operation within satisfactory parameters.

I avoid using pots, as i have found with extreme temperature cycles and moisture they become unreliable. I also avoid using relays and mechanical switches.

Paul...thanks for those links too Jmarko