YOKOGAWA ZR202S, User Manual, Page: 87 / 163

<8. Detailed Data Setting>
8-6
IM 11M13A01-04E
8.4 Oxygen Concentration Alarms Setting
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 Setting the 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 be set in the range of 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 limit 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