I'm measuring wind direction every second using a 360 degree pot (actually 0-355 as there is a 5 deg dead band) and am using the low current 200 uA excitation option in order to extract the variable voltage.

I don't think I can use the resistance method because of the dead zone of the pot. My first question is how long will the mechanical relay that is actuated every second last?

It sounds like a relay but I'm not sure if it is - sounds mechanical though! Second question is how does one derive average direction with a voltage output device like this one when facing a northerly direction (average will result in South which is incorrect)?

Thanks for any help,
Bill

Good morning Bill,

The relay has a MTBF of 10^8 cycles when switching one Amp.
The relays in the DT80 are exactly the same as the ones in the DT505 range of loggers.We have been using them for about 15 years now and we have no record of the relays failing due to mechanical wear.

The wind direction code is in the FAQ: http://www.thermofisher.com.au/show.aspx?page=/ContentAUS/Manufacturing-Processing/Industrial-Loggers/DataTaker/DataTaker-FAQ/Program-Code/General-Weather-Station-Codes.html

Cheers,
Roger

Hi Roger,

Just to pick up on this thread again...

The MTBF of 10^8 cycles at 1 amp - I gather this is contact rating so if this is the case does the number of cycles increase with a corresponding drop in load current (say switching milliamps)?

What about mechanical failures? If I want to sample at 2hz then the 10^8 count will be approached within a year and a half not to mention the cacophony of noise the thing will make...

Has there been recorded failures of these relays at all? Your comments will be welcome.

Cheers,
Bill

Good evening Bill,

We have been using he same relays in the DT5X5 for over 15 years and don't have any record of a mechanical failure yet.

Cheers,
Roger