YOKOGAWA UTAdvanced UP55A, User Manual

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10-10
IM 05P02C41-01EN
10.7 Setting ON/OFF Control Hysteresis
Description
In ON/OFF control, since the only two possible output states are ON and OFF, the control
output cycles are as shown in the figure below. ON/OFF becomes quite narrow, so that if
relay output is used, chattering occurs. In this case, the hysteresis should be set wider to
prevent relay chattering and for the service life of the relay.
One Point of Hysteresis
For one point of hysteresis, set one point of hysteresis. In Heating/cooling control, set
heating-side ON/OFF control hysteresis and cooling-side ON/OFF control hysteresis.
Hysteresis
SP
Output
ON
ON
OFF
OFF
ON ON
OFF
PV
Hysteresis
SP
Output
(Example of reverse action)
Temperature
Two Points of Hysteresis
For two points of hysteresis, set two points of hysteresis (upper-side hysteresis and
lower-side hysteresis).
Two points of hysteresis cannot be used for Heating/cooling control.
Upper-side
hysteresis
Lower-side
hysteresis
SP
Output
ON
ON
OFF
OFF
ON ON
OFF
PV
Upper-side hysteresis
Lower-side hysteresis
SP
Output
(Example of reverse action)
Temperature