Azbil dcp551 mark II, Руководство пользователя

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5-35
• Automatic changeover B
To combine external switch input conditions with automatic changeover A,
enter 2 in setup data setting C26 and 9 or 10 in one of settings C71 to C74 .
When 9 is entered in C71 to C74 and the external switch is on, it is tied to
channel 1. When it is off, it is possible to switch channels from channel 1 to 2.
When 10 is entered in C71 to C74 and the external switch is on, it is tied to
channel 2. When it is off, it is possible to switch channels from channel 2 to 1.
• Automatic changeover C
Enter 2 in setup data C26 when the PV to be calculated is the value between the
low-temperature sensor and high-temperature sensor in the dead band range.
The switch operation is described in the following example.
(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-temperature 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.
Result of automatic
changeover A operation
Conditions
External switch set
to 9 ( PV1 PV2 )
External switch set
to 10 ( PV2 PV1 )
Result of automatic
changeover B operation
CH1 CH2
OFF ON Nothing OFF ON Nothing
Nothing OFF ON
Nothing OFF ON
CH1 CH1 CH1 CH2 CH2 CH2
Chapter 5. FUNCTIONS
B
C
1/2 dead
band
1/2 dead
band
Changeover
setting
Low temper-
ature sensor
Intermedi-
ate area Intermedi-
ate area
High temper-
ature sensor
Low temperature
sensor
D
Low temper-
ature sensor
A
High temper-
ature sensor
High temper-
ature sensor