Yokogawa Single Channel Oxygen Analyzer System ZR22/ZR402 - Manual (Page 125)

IM 11M13A01-02E 8-8
In the example in Figure 8.4, the high-limit alarm point is set to 7.5% O
2
, the delay time
is set to five seconds, and hysteresis is set to 2% O
2
.
Alarm output actions in this figure are as follows:
(1) In “A” Although oxygen concentration value exceed the high-limit alarm setpoint, it
falls lower than the high-limit alarm setpoint before the preset delay time of five
seconds elapses. So, no alarm is issued.
(2) In “B” Oxygen concentration value exceeds the high-limit alarm setpoint and the
delay time elapses during that measurement. So, an alarm results.
(3) In “C” Although oxygen concentration value falls lower than the hysteresis set value,
the value rises again and exceeds the hysteresis set value before the preset delay time
elapses. So, the alarm is not canceled.
(4) In “D” Oxygen concentration value falls below the hysteresis set value and the preset
delay time elapses, so the alarm is canceled.
8.3.3 Alarm Setting Procedure
To set the alarm setpoints, follow these steps:
(1) Press the Setup key in the basic panel display to display the Execution/Setup display.
(2) Select Setup in the Execution/Setup display. The “Commissioning” (Setup) display
then appears.
(3) Select the Alarm setup in the “Commissioning” (Setup) display. The Alarms setup
display shown in Figure 8.5 then appears.
• To set the hysteresis, proceed to the following steps.
(4) Select Hysteresis in the Alarm setup display. The numeric-data entry display then
appears. Enter the desired hysteresis value as a percent of oxygen concentration. To
set 2.5% O
2
, enter “0025.” The hysteresis setting can be in the range 0 to 9.9% O
2
.
• To set the delay time, proceed as per the following steps.
(5) Select the Contact delay in the Alarms setup display. The numeric-data entry display
then appears. Enter the desired delay time, in seconds. To set three seconds, enter
“003.” The delay time setting can be in the range 0 to 255 seconds.
• To set the alarm point, proceed to the following steps.
(6) Select the Setpoints in the Alarms setup display. The Oxygen alarms display then
appears, as shown in Figure 8.6.
(7) When you select “High alarm” in the Oxygen alarms display, the “off” or “on”
selection display then appears. If you select “on,” the High alarm will then be
enabled (enable/disable).
(8) To set the High alarm values select “Set value” just below the High alarm. The
numeric-data entry display then appears. Enter the alarm set value (percent of oxygen
concentration). If you want to set the alarm value to 10% O
2
, enter “010.”
(9) Set the other alarm settings in the same manner as in the steps above.
CAUTION
No alarm is issued when alarm is set to “off” (disabled). To use the alarm functions, be
sure to set the alarms “on”.