Teledyne 3220 - Multi-channel oxygen monitor system - Manual (Page 20)

2 Operational Theory Model 3220
Teledyne Analytical Instruments 6
Operational Theory
2.1 Introduction
The Model 3220 combustible gas analyzer is composed of four
components:
1. System Chassis
2. Control Unit
3. Channel Modules
4. Micro-fuel Cell
The System Chassis provides structural support and electrical
interconnection for a Control Unit and up to eight Channel Modules. Each
Channel Module can monitor one sensor.
2.2 System Chassis
All electrical connections are located on the rear of the system
chassis. There are nine terminal strips, one for each of the Channel
Modules and one for the Control Module.
2.3 Control Unit
The Control Unit provides control of electrical power to the
channel module, audio alarms and external alarms through the common
alarm relays. The front panel of the Control Unit is shown if Figure 2-1
Alarm signals from any Channel Module trigger the corresponding
relays in the Control Unit. For example, “alarm 1” signals from any channel
trigger the “alarm 1” relay in the system control module. There are three
such relays in the Control Unit, one each for alarm 1, alarm 2, and failure
alarms. The failure alarm relay in the Control Unit is operated “fail-safe”;
however, the gas level alarm relays can be optionally connected for operation
in the “non fail-safe” mode by setting the configuration jumpers as indicated
in the installation section 3.6.2. Each of these relays provides SPDT contacts
for operation of external devices.