Teledyne 7120 - NDIR analyzer - Manual (Page 54)

Infrared Analyzer Operation 4
4-21 Teledyne Analytical Instruments
is pressed, the Span reading changes to the correct value. The instrument then
automatically enters the Analyze function.
4.5 The Alarms Function
The Model 7100 is equipped with 6 fully adjustable set points concentra-
tion with two alarms and a system failure alarm relay. Each alarm relay has 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 fail-safe or non-fail-safe, 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
contaminant concentration rises above the setpoint. Setting an
alarm as LOW triggers the alarm when the contaminant
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.
3. Are either of the alarms to be latching?
In latching mode, once the alarm or alarms trigger, they will
remain in the alarm mode even if process conditions revert back
to non-alarm conditions. This mode requires an alarm to be
recognized before it can be reset. In the non-latching mode, the