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Percent Oxygen Analyzer Installation
Teledyne Analytical Instruments 27
The alarm relay circuits are designed for failsafe operation,
meaning the relays are energized during normal operation. If power fails
the relays de-energize (alarms activated).
The contact connections are indicated diagrammatically on the rear
panel as Normally Closed, Common, and Normally Open. Figure 3-3
explains how these act in failsafe operation.
Alarm 1 and Alarm 2 are configured as HI and LO respectively. A
HI alarm will activate when concentration is above threshold, while a
LO alarm will activate when concentration is below threshold.
Figure 3-3: Contact ID for FAILSAFE Relay Operation
The specific descriptions for each type of alarm are as follows:
Alarm #1 Programmable as high alarm. Can be set anywhere
between 0 and 100 % but no lower than Alarm #2.
Alarm #2 Programmable as low alarm. Can be set anywhere
from 0 to 100 % but no higher than Alarm #1.
Sensor Fail Actuates when the output of the sensor falls below a
factory programmed acceptable level or the
thermocouple is open.
CAUTION: THERE COULD BE HAZARDOUS VOLTAGE AT THE
ALARMS TERMINALS, EVEN WHEN POWER IS
REMOVED FROM THE INSTRUMENT.