Honeywell DCP551 Mark ΙΙ User Manual page 84

• Automatic changeover B
To combine external switch input conditions with automatic changeover A, enter 2
in setup data setting
When 9 is entered in
When it is off, it is possible to switch channels from channel 1 to 2.
When 10 is entered in
When it is off, it is possible to switch channels from channel 2 to 1.
Result of automatic
changeover A operation
External switch set
®
to 9 ( PV1 PV2 )
External switch set
®
to 10 ( PV2 PV1 )
Result of automatic
changeover B operation
• Automatic changeover C
Enter 2 in setup data
temperature sensor and high-temperature sensor in the dead band range. The switch
operation is described in the following example.
Low temperature
sensor
Changeover
setting
A
Intermedi-
Low tempe-
rature sensor
ate area
(1) When the high-temperature sensor senses that the temperature has dropped
below point A, the lower dead band limit, the channel switches from the high-
temperature sensor to the low-temperature sensor.
(2) When the high-temperature sensor senses that the temperature has risen to
between point A, the lower dead band limit, and point B, the higher dead band
limit, the controller calculates the value between the low-temperature sensor and
the high-temperature sensor. The ratio of the high-temperature sensor varies
between 0% at point A and 100% at point B.
(3) When the high-temperature sensor senses that the temperature has risen above
point B, the higher dead band limit, the channel switches from the low-tempera-
ture sensor to the high-temperature sensor.
(4) When the high-temperature sensor senses that the temperature has dropped
below point C and is going towards point D, the controller calculates the value
between the low-temperature sensor and the high-temperature sensor.
C26
and 9 or 10 in one of settings
C71 C74
to and the external switch is on, it is tied to channel 1.
C71 C74
to and the external switch is on, it is tied to channel 2.
CH1
OFF ON Nothing
Nothing OFF ON
CH1 CH1
C26
when the PV to be calculated is the value between the low-
B
High tempe-
rature sensor
High tempe-
rature sensor
Chapter 5. FUNCTIONS
C71 C74
to .
CH2
OFF ON Nothing
Nothing OFF ON
CH2 CH2 CH1 CH2
C
High tempe-
rature sensor
D
Intermedi-
Low tempe-
rature sensor
ate area
1/2 dead
band
1/2 dead
band
5-35