Brainchild C21 User Manual page 36

Heat Only ON-OFF Control : Select REVR for OUT1, Set PB to 0, Heat Only ON-OFF Control : Select REVR for OUT1, Set PB to 0,
O1HY is used to adjust dead band for ON-OFF control, The output 1 O1HY is used to adjust dead band for ON-OFF control, The output 1
hysteresis ( O1HY ) is enabled in case of PB = 0 . The heat only hysteresis ( O1HY ) is enabled in case of PB = 0 . The heat only
on-off control function is shown in the following diagram : on-off control function is shown in the following diagram :
PV
SP1
SP1 O1HY
OUT1 Action
ON
OFF
Figure 3.2 Heat Only Figure 3.2 Heat Only
The ON-OFF control may introduce excessive process oscillation even The ON-OFF control may introduce excessive process oscillation even
if hysteresis is minimized to the smallest. If ON-OFF control is set ( ie. if hysteresis is minimized to the smallest. If ON-OFF control is set ( ie.
PB = 0 ), TI, TD, CYC1, OFST, CYC2, CPB, DB will be hidden and have PB = 0 ), TI, TD, CYC1, OFST, CYC2, CPB, DB will be hidden and have
no function to the system. The auto-tuning mode and bumpless no function to the system. The auto-tuning mode and bumpless
transfer will be disabled too. transfer will be disabled too.
Heat only P ( or PD ) control : Heat only P ( or PD ) control :
OFST is used to adjust the control offset ( manual reset ). OFST is used to adjust the control offset ( manual reset ).
hidden hidden if PB is not equal to 0. if PB is not equal to 0.
% with range 0 - 100.0 %. In the steady state ( ie. process has been % with range 0 - 100.0 %. In the steady state ( ie. process has been
stabilized ) if the process value is lower than the set point a definite stabilized ) if the process value is lower than the set point a definite
L L
value, say 5 C, while 20 C is used for PB, that is lower 25 %, value, say 5 C, while 20 C is used for PB, that is lower 25 %,
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ON-OFF Control ON-OFF Control
Select REVR for OUT1, set TI to 0, Select REVR for OUT1, set TI to 0,
OFST Function : OFST Function :
L L
UM0C911A
Dead band = O1HY
Time
Time
O1HY is O1HY is
OFST is measured by OFST is measured by