How to maintain a bank of standard cells

[zhtoor]

Hello everybody,

what would be the proper way to maintain a set of saturated standard cells ?

1. oil bath design
2. temperature range
3. humidity issues
4. automatic comparison / back-to-back nulling system
etc...

regards.

[Conrad Hoffman]

Really broad question. IMHO, the best way to maintain them is not to disturb them. Temperature control can be air or oil- double air ovens have been used, like Julie Research did with theirs. It should be battery backed with a substantial capacity battery because recovery time is long. Most degradation probably comes from frequent over enthusiastic comparisons. Depending on what you need to do, comparisons once a month or even twice a year might be sufficient.

[edpalmer42]

Maybe start with this:

NBS Monograph 84
Standard Cells:  Their Construction, Maintenance, and Characteristics

https://archive.org/details/standardcellsthe84hame_0

AFAIK, most of the 'ordinary' commercial Standard Cells (Eppley, Guildline, etc.) use air baths rather than oil.

Ed

[ManateeMafia]

Question #4 start with this... http://www.dataproof.com/NBS430.PDF

You will need a meter that can measure down in the nanovolt ranges. You would also need a switching system similar to the Data Proof scanners. It can be built by using some low thermal emf relays.

The NBS430 doc includes examples and they were handy when I started writing my software. Making it automated is nice but could end up being costly unless you plan on adding several cells.

[zhtoor]

Question #4 start with this... http://www.dataproof.com/NBS430.PDF

You will need a meter that can measure down in the nanovolt ranges. You would also need a switching system similar to the Data Proof scanners. It can be built by using some low thermal emf relays.

The NBS430 doc includes examples and they were handy when I started writing my software. Making it automated is nice but could end up being costly unless you plan on adding several cells.

thank you, that is what i was looking for.

I plan to have 9 cells in the system (maybe more if i can acquire more).

regards.

[zhtoor]

Really broad question. IMHO, the best way to maintain them is not to disturb them. Temperature control can be air or oil- double air ovens have been used, like Julie Research did with theirs. It should be battery backed with a substantial capacity battery because recovery time is long. Most degradation probably comes from frequent over enthusiastic comparisons. Depending on what you need to do, comparisons once a month or even twice a year might be sufficient.

thanks sir,

i have a 24VDC / 20AH NiCd battery with an associated charger for backup purposes.
sometimes we have electricity outages of 5+ hours.

regards.