Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 106)

IM 11M12A01-05E 8-9
8. Detailed Data Setting
8.3 Alarm Setting
The analyzer provides four alarms — high-high, high, low, and low-low alarms -
settable with measured values. The following sections describe the alarm operations and
setting procedures for the oxygen concentration, humidity, and mixing ratio.
8.3.1 Alarm Values
(1) High-high and high alarm values
High-high alarms and high alarms are issued when they are set to be detected, and if
the measured values exceed the preset values.
(2) Low and low-low alarm values
Low alarms and low-low alarms are issued when they are set to be detected, and if the
measured values are lower than the preset values..
8.3.2 Alarm Output Actions
If the measured values of the oxygen concentration fluctuate between normal (steady-
state) values and alarm setpoints, there may often be a lot of alarm-output issuing and
canceling. To avoid this, set the delayed time and allow for hysteresis for alarm cancel-
ing uneƥ0the alarm output conditions, as Figure 8.2 shows. When the delay time is
set, an alarm will not be issued so quickly even though 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, a similar way as in the above will be done 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
setting 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 time
is after the preset delayed time. Refer to Figure 8.2 for any further alarm output actions.
The delay time and hysteresis settings are common to all alarm points.
Delay time:
5 seconds
7.5%
High-limit alarm setpoint
5.5%
Humidity
Alarm output ON
OFF
Hysteresis
2.0%
A B C D
Alarm range
Delay time:
5 seconds Delay time:
5 seconds
F8.2E.EPS
Figure 8.2 Alarm Output Action