Yokogawa Single Channel Oxygen Analyzer System ZR22/ZR402 - Manual (Page 121)

IM 11M12A01-03E 8-9
8. Detailed Data Setting
8.3 Alarm Setting
The analyzer enables the setting of four alarms — high-high, high, low, and low-low
alarms — depending upon the measurement conditions. The following section sets forth
the alarm operations and setting procedures.
8.3.1 Alarm Values
(1) High-high and high alarm values
If high-high and high alarm values are set to ON, then alarms occur if measured
values exceed the alarm set values.
(2) Low and low-low alarm values
If low-low and low alarm values are set, then alarms occur if measured values fall
below the alarm set values.
8.3.2 Alarm Output Actions
If the measured values 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 alarm
delay and hysteresis for alarm canceling under the alarm output conditions, as Figure 8.4
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 greater 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 delayd 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 has elapsed. Refer to Figure 8.4 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
F8.4E.EPS
Figure 8.4 Alarm Output Action