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TELEDYNE INSTRUMENTS
Operating Instructions 460L Instruction Manual
26 05228 Rev B
PRINTED DOCUMENTS ARE UNCONTROLLED DCN 5164
6.2. Concentration Alarms
There are two O
3
concentration alarms, HI and HI-HI. Both alarms are triggered when the
measured O
3
concentration equals or rises above the set limit for that alarm. The set limit for
HI alarm must always be a lower value than that of the HI-HI alarm. If the O
3
concentration is
between the HI limit and the HI-HI limit, the HI alarm will be active, but the HI-HI alarm will be
inactive.
When either the HI or the HI-HI alarms are active the ALARM ACTIVE status LED on the front
panel (see Figure 3-1) will blink. In addition when the HI alarm is active alarm trigger LED D7 (on
the main PCA, see Figure 3-12) will glow and when the HI-HI alarm is active alarm trigger LED
D8 will glow.
6.2.1.1. Concentration Alarm Configuration
Either of the concentration alarms can be independently configured via the 460L’s serial
communication port (see Section 7.3.11).
The user can set the alarms to operate in either the latching or non-latching as well as
independently adjust the trigger levels of the alarm limits.
In non-latching mode, the alarms will be triggered when O
3
concentration equals or exceeds the
associated limit is reached and will automatically return to an inactive state if the O
3
concentration
falls below the limit level. In latching mode once an alarm is triggered it will stay active until
cleared by the user regardless of how the O
3
concentration measurement changes.
6.2.1.2. Remotely Sensing the Status of the Alarm
Besides the LEDs located on the front panel and on the monitor’s main PCA, the status of each
alarm can be sensed externally via a single-pull, double-throw relay (see Section 3.5.4) or
determined from a remote locati
on via the monitor’s serial communication port (See Chapter 7).
6.2.1.3. Clearing Alarms
When set for non-latching mode the alarms will only clear when the alarm condition disappears
and will do so automatically. When in latching mode, the concentration alarms may be cleared in
several ways:
FRONT PANEL: Pressing the ALARM ACKNOWLEDGE key on the monitor’s front panel
will clear all active alarms.
SERIAL COMMUNICATION PORT: The ALMACK command to clear all active alarms (see
Section 7.3.1)
Table 6-2 Concentration Alarm Default Settings
ALARM CONDITION MODE TRIGGER LIMIT
HI 100 ppb
HI-HI
Enabled Latching
300 ppb