[volt-nuts] AC voltage "standards".

[Chuck Harris]

Those are not references, but rather are AC thermal
transfer standards.

The way they work is you apply an unknown AC voltage
to it, and measure the DC voltage generated by
its thermocouple.  Then you remove the AC voltage,
and apply a DC voltage that gives the same thermocouple
voltage.  Usually, you apply the DC voltage with both
polarities, and average the two readings... which helps
to null out any thermocouple errors.

To successfully use an AC thermal transfer standard it
helps to have the controller instrument that goes along
with it.

Fluke makes as nice setup, as did HP.

At their best, they are twidgety, and quite sensitive to
ambient temperature variations, physical orientation,
air currents....  Apply too much voltage, and like the
light bulbs that they resemble, they go poof!

I don't think any metrologist has ever been truly happy
with the AC thermo transfer standard.

-Chuck Harris



John Phillips wrote:
> Is there a better AC reference I can afford than
> http://www.ballantinelabs.com/1395.htm     1395B-XX
>