Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 89)

<8. Detailed Data Setting>
8-6
IM 11M12A01-04E
8.4 Setting Oxygen Concentration Alarms
The analyzer enables the setting of four alarms high-high, high, low, and low-low alarms depending
upon the oxygen concentration. The following section sets forth the alarm operations and setting
procedures.
8.4.1 Alarm Values
(1) High-high and high alarm values
High-high alarms and high alarms are issued when they are set to be detected with parameter
codes 「D41」 and 「D42」, and if the measured values exceed the preset oxygen concentration
values specified with 「D01」 and 「D02」.
The oxygen alarm set values can range from 0 to 100% O
2
.
(2) Low and low-low alarm values
Low alarms and low-low alarms are issued when they are set to be detected with parameter
codes 「D43」 and 「D44」, and if the measured values are lower than the preset oxygen
concentration values specified with 「D03」 and 「D04」.
The oxygen alarm set values can range from 0 to 100% O
2
.
8.4.2 Alarm Output Actions
If the measured values of the oxygen concentration fluctuate between normal (steady-state) values
and alarm setting, there may be a lot of alarm-output issuing and canceling. To avoid this, set the
delay time and allow for hysteresis for alarm canceling under the alarm output conditions, as Figure
8.2 shows. When the delay time is set, an alarm will not be issued so quickly even if the measured
value differs from the steady-state and enters the alarm setpoint range. If the measured value remains
within the alarm setpoint range for a certain period of time (for the preset delay time), an alarm will
result. On the other hand, there will be a similar delay each time the measured value returns to the
steady state from the alarm setpoint range (canceling the alarm status). If hysteresis is set, alarms will
be canceled when the measured value is less than or more than the preset hysteresis values. If both
the delay time and hysteresis are set, an alarm will be issued if the measured value is in the alarm
setpoint range and the delay time has elapsed. When the alarm is reset (canceled), it is required that
the measured value be beyond the preset hysteresis value and that the preset delay time. Refer to
Figure 8.2 for any further alarm output actions. The delay time and hysteresis settings are common to
all alarm points.
Delayed time:
5 seconds
7.5%
High alarm setpoint
5.5%
Oxygen concentration
Alarm output ON
OFF
Hysteresis
2.0%
A B C D
Alarm range
Delayed time:
5 seconds
Delayed time:
5 seconds
F8.2E.ai
Figure 8.2 Alarm Output Action