System Hardware Overview
Manual Part Number:
5-06-4900-53-0
Revision Level: C
ECO 044952
Revision Date:
May 08, 2018
Page 1-6
1.4
System Inputs and Outputs
1.4.1 Oxygen Sensor Input
The Oxygen Sensor electrical input is used to indicate the Oxygen level concentration in a process
vessel headspace, or a process gas stream. Sensors are available to measure the Oxygen
concentration in percent by volume or partial pressure in the ranges from 0.1% to 25.0%, and 0.1%
to 50.0%. All available Neutronics Inc. Sensors are Intrinsically Safe, remote-mounted devices,
and may be interfaced through electrical safety barriers for hazardous applications,
1.4.2 Flow Switch Status Input
The Flow Switch Status electrical interface is used to indicate the flow status of sample gas from
the process to the Oxygen Sensor, for extractive applications where a Neutronics Inc. Sampling
System has been provided. A closed flow switch indicates sufficient sample flow. An open Flow
Switch indicates that sample flow has dropped below the mechanical set point of the Flow Switch.
In this flow condition, the Oxygen reading may not be representative of the process Oxygen level.
Neutronics Inc. Flow Switches are Intrinsically Safe, and may be interfaced through electrical
safety barriers for hazardous applications.
1.4.3 O
2
Alarm Relay Output
The Oxygen Alarm relay is mapped to the O
2
Alarm setpoint, and is provided for process control
use. The user may set the level at which the O
2
Alarm activates (section 3.2.2). The O
2
Alarm
may be configured as ascending (highest Oxygen level allowable) or descending (lowest Oxygen
level allowable) activation. The relay output may be configured for fail-safe (relay coil de-
energized in alarm state) or non fail-safe (relay coil energized in alarm state) activation. Factory
default settings are ascending, and fail-safe (Appendix C, Factory Configuration). The O
2
Alarm
relay contacts are form C (DPDT), voltage-free.
1.4.4 Inert Gas Control Relay Output
The Inert Gas Control (ICS) relay is mapped to the Inert Gas Control high and low limit setpoints,
and is provided for process control use. The user may set the levels at which Inert Gas Control
activates (high limit setpoint), and de-activates (low limit setpoint). The relay output may be
configured for fail-safe (relay coil de-energized in alarm state) or non fail-safe (relay coil energized
in alarm state) activation. The factory default setting is fail-safe (Appendix C, Factory
Configuration). The ICS relay contacts are form C (DPDT), voltage-free.
The purpose of the ICS relay is to control the flow of inert gas to the process being monitored, to
keep Oxygen levels in the process within an acceptable range at all times. Purging the process
with inert gas lowers the Oxygen concentration in the process. The Mini-ICS Analyzer will activate
the ICS relay when the Oxygen concentration rises to the High ICS limit setpoint. It will deactivate
the ICS relay when the Oxygen concentration falls below the Low ICS limit (sections 3.2.3 and
3.2.4).
1.4.5 Fault Relay Output
The Fault relay output is used to indicate that there is at least one system fault active on the Model
Mini-ICS Analyzer (section 4.3.1
– fault codes and definitions). The Fault relay contacts are Form B
(SPST), voltage-free.
Note
: The user can configure the ICS relay to activate on certain Fault conditions for process
safety applications (sections 4.1.2.9, and Appendix C).
