Honeywell DCP551 Mark ΙΙ User Manual page 82

• Automatic changeover A
Set 1 in setup data setting
(switch point) where channels are switched and the dead band setting that prevents
switch chattering. Examples 1 to 4 below describes switch operations.
Example 1:
Low temperature
sensor
Changeover
setting
Low tempe-
rature sensor
(1) When the high-temperature sensor senses that the temperature has risen to
changeover point A, the channel switches from the low-temperature to the high-
temperature sensor.
(2) No switching is performed at changeover point C when the high-temperature
sensor senses that the temperature has only reached point B and does not exceed
the upper limit of the dead band.
(3) When the high-temperature sensor senses that the temperature has dropped to
point D the lower limit of the dead band, the channel switches from the high-
temperature to the low-temperature sensor.
Example 2:
Low temperature
sensor
Changeover
setting
Low tempe-
rature sensor
(1) When the temperature rises and the high-temperature sensor senses that the tem-
perature has risen to changeover point A, the channel switches from the low-
temperature sensor to the high-temperature sensor.
(2) When the high-temperature sensor senses that the temperature has risen above
the upper limit of the dead band and reached point B, the channel switches from
the high-temperature to the low-temperature sensor at changeover point C.
C26
to allow automatic changeover to set the temperature
B
C
A
High tempe-
D
rature sensor
High tempe- Low tempe-
rature sensor rature sensor
B
C
A
High tempe-
rature sensor
High tempe- Low tempe-
rature sensor rature sensor
Chapter 5. FUNCTIONS
+
1/2 dead band
1/2 dead band
Ð
+
1/2 dead band
1/2 dead band
Ð
5-33