Glossary - Vemer HT NiPt Series User Manual

Set point (set or operating point)
• The set point is the value at which the appliance has to intervene to maintain the
measurement controlled at the required level.
Differential (or hysteresis)
• The differential is the maximum permitted variation from the set point for
the measurement controlled prior to the intervention of the appliance.
• This is usually set in such a way as to prevent rapid oscillations in the
measurement around the set point from causing frequent start-ups and
shutdowns of the appliance or the driver connected to it.
Direct action
• A regulator acts in direct mode when it
limits the measurement as this increases.
A typical example is a refrigerator: the
increase in temperature corresponds to
an increase in the refrigeration power
produced, with a view to reducing the
temperature
Reverse action
• A regulator acts in reverse mode
when it limits the reduction of the
measurement controlled.
For example, in a heating system, the
reduction in temperature
corresponds to an increase in heat
production
Neutral or dead zone ("dead-band")
• This indicates an interval of values around the set point in which the measurement
regulated may oscillate without the activation of any output. It is normally used in
the appliances in which there is a strong inertia of the system, as a result of which
the set point may be exceeded even after the driver has been switched off or to
prevent the overlap of a heating and cooling action.
Around the neutral zone, no
output is activated. Outside the
neutral zone, the instrument
operates in direct mode if the
measurement controlled
increases, and in reverse if it
decreases.

GLOSSARY

ON
OFF
Set - Diff (R) - ZN
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User Manual Digital Heat Regulators
Direct Mode
ON
D
OFF
Set Set + Diff
Temperature
Reverse Mode
ON
R
OFF
Set Diff Set
Temperature
Neutral Zone Mode
R
ZN
ZN
Set
Temperature
D
Set + Diff (D) + ZN