[volt-nuts] Fluke 720A Kelvin Varley Divider Questions

[Myers, Charlie]

Hi to everyone,

I am new to this group and have a keen interest in precision and accurate voltage references and metrology.  I am using a pair of Fluke 732A Reference Voltage Sources for my voltage standards and a Fluke 5440B Direct Voltage Calibrator in my home lab. I am thinking about acquiring a Kelvin Varley voltage divider for a number of lab uses including scaling of my 10 volt standards so that I can calibrate my Fluke 5440B and, in turn, various DMMs.  The most precision DMM I own is an HP 3457A 6 ½ digit multimeter which can be extended to 7 ½ digits by adding the contents of the 7th digit register to the displayed reading.

My question is how stable are the Fluke 720A dividers over time, i.e., if I have one that is in calibration (+/- 0.1 ppm accuracy and linearity) will it tend to stay that way over the course of years assuming that I don't apply excessive voltage, dissipate excessive power, or otherwise abuse the divider?  Or will it need to be calibrated on an annual basis to keep it within reasonable specifications?  I don't require +/- 0.1 ppm accuracy but I would like to maintain somewhere between +/- 0.5 ppm accuracy and  +/- 1ppm accuracy over time.

All advice and comments are welcome.  For me, this is a new area of learning and adventure.

Thanks.

Charlie