Annex 170
29.2. GLOSSARY
cleaning automatic procedure to stop control, clean the electrode and then activate control
again
data acquisition conversion of analog signals received from the probe sensor to digital representations
that can be processed by a computer
dead band an area where the absolute value of the error between Set point and process value
is considered 0
dead band gain a coefficient applied to PID integrative term in the Dead Band area
deviation an interval aligned with Set point value, where control output can take values from
0 % to 100 %. It is measured in process‑value units.
fail safe alarm Signaling of the alarm by de‑energizing the alarm relay instead of energizing it.
Protects against power failures and interruptions of the alarm relay external wires.
hysteresis interval that must be exceeded by the controlled magnitude in the opposite direction
after having activated a relay, before deactivating it, in order to avoid uninterrupted
relay activation or deactivation
minimum On time the time that control output is minimum On, necessary to protect elements that are
driven
overtime a safety parameter provided to set the maximum continuous time control is running
at it’s maximum value
potential matching pin is a titanium which must be immersed into the measured fluid. It is used together
with a differential input to avoid damage of the reference electrode due to ground
loop current.
sequential control control‑loop system whereby users have the option to run channel control
independently or configure to be triggered sequentially
set point desired value for the controlled parameter
solution compensation technique for compensating the differences on the pH of the solution under
measurement when its temperature varies
threshold value above / below which a control or alarm relay is activated or deactivated
trigger an event or command that acts like a mechanical trigger in initiating a process
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