Potroom Digital Voltmeters
Electrochemical Reduction
of Aluminum Ore
The electrochemical reduction
of aluminum from its ore involves large d.c. currents which
flow through a series-connected array of electrolytic cells,
or "pots". The voltage drop across each "pot" is about 6 volts
DC during useful operation, but climbs significantly in the
case of ore depletion, electrode contamination, etc. Individual
voltmeters are routinely provided to monitor these "pot" voltages
for the detection of problems and run status.
The "Pot Room" application
calls for the following special features in a 0-10 VDC DPM:
- Common Mode Voltage: since
the "pots" at the input end of the series string may be
up to 1000 VDC above ground, the DPM must be capable of
at least 1250 volt isolation between power and signal inputs.
Separate external isolation 5000 V transformers can be purchased
to power mtr. or split input transistor for DC can be supplied.
- Electrical Noise: the "pot
room" environment is very noisy, so that extra internal
filtering and bypassing of power supplies is necessary.
- "Spike Protection": the
a.c. power line is likely to contain substantial "spikes"
which could damage the DPM; a G.E. type V130LA10A varistor
should be wired in parallel with AC input at the connector
when the DPM is installed.
- Dust/Moisture: the "pot
room" is likely to contain conductive dust and halogens
(esp. fluorine); since DPM's cannot be made impervious to
these contaminants, the user must be prepared to locate
the DPM's within a suitable NEMA-grade enclosure equipped
with an appropriate viewing window. This will also permit
"fire hose" washdown procedures.
We sell a splash cover for mounting
outside of the meter as well as a plastic mounting adapter
to cover up analog meter holes.
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