
6 Control for Aluminum Production
Mike Brisk, of Sydney University in Australia, performed surveys of
PID (proportional–integral–derivative) control loops in both the United
States and in Australia
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because of a perceived lack of attention to the
basics of process control. He found that between 61 and 65% of the
100,000 PID loops surveyed in each country were not operating correctly
(either turned off/manual, or having exceeded their control ranges).
His conclusion from these surveys was that we need to pay attention
to the controllers and make sure they are operating before consider-
ing so called “advanced control” systems. This conclusion clearl ...