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Operation
to the correct value. The instrument then automatically enters the
ANALYZE function.
4.9 The ALARMS Function
The Model 3020T is equipped with 2 fully adjustable concentration
alarms and a system failure alarm. Each alarm has a relay with a set of
form "C" contacts rated for 3 amperes resistive load at 250 V ac. See
Figure in Chapter 3, Installation and/or the Interconnection Diagram
included at the back of this manual for relay terminal connections.
The system failure alarm has a fixed configuration described in
chapter 3 Installation.
The concentration alarms can be configured from the front panel as
either high or low alarms by the operator. The alarm modes can be set as
latching or non-latching, and either failsafe or non-failsafe, or, they can
be defeated altogether. The setpoints for the alarms are also established
using this function.
Decide how your alarms should be configured. The choice will
depend upon your process. Consider the following four points:
1. Which if any of the alarms are to be high alarms, and which if
any are to be low alarms?
Setting an alarm as HIGH triggers the alarm when the oxygen
concentration rises above the setpoint. Setting an alarm as LOW
triggers the alarm when the oxygen concentration falls below the
setpoint.
Decide whether you want the alarms to be set as:
Both high (high and high-high) alarms, or
One high and one low alarm, or
Both low (low and low-low) alarms.
2. Are either or both of the alarms to be configured as failsafe?
In failsafe mode, the alarm relay de-energizes in an alarm
condition. For non-failsafe operation, the relay is energized in an
alarm condition. You can set either or both of the concentration
alarms to operate in failsafe or non-failsafe mode.
Teledyne Analytical Instruments
Model 3020T
48
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