Sensor check (model with cp compensation) – Honeywell DCP552 Mark II User Manual
Page 77
5-31
■ O
2
sensor check (model with CP compensation)
● Objective
As the O
2
sensor starts to deteriorate, its output impedance increases. This function
checks sensor output impedance and turns on the O
2
sensor error event when the
impedance exceeds 130kΩ.
● Setting
•One of the values set for setup data
C71
to
C74
is set to 11 to assign the O
2
sensor check to an external switch.
•One of the values set for event configuration data setting
E01-t
to
E16-t
is set to
142 to assign an O
2
sensor error event.
● Operation
•Two methods are used to perform an O
2
sensor check. In one method the external
switch which has been assigned the O
2
sensor check function goes from OFF to
ON. This is called a constant check.
•The other method the external switch is turned on each 24-hour period. This is
called an automatic check.
•The impedance is checked when PV1 is 800 °C or more and the O
2
input is
1000mV or higher.
•The O
2
sensor error event goes on when sensor impedance exceeds 130k;Ω
otherwise it remains off.
•The constant check method is shown below.
•The automatic check method is shown below.
Chapter 5. FUNCTIONS
Sensor
replacement
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
OFF
OFF
ON
ON
OFF
130k½
External switch
O
2
sensor check
O
2
sensor
impedance
Event output
(O
2
sensor error)
Impedance
Time
OFF
ON
OFF
OFF
ON
ON
OFF
24 hours 24 hours
24 hours
Sensor
replacement
130k½
External switch
O
2
sensor check
O
2
sensor
impedance
Event output
(O
2
sensor error)
Impedance
Time