Teledyne 4020 – Hydrocarbon analyzer (special version for automatic background gas switching) - Manual (Page 39)

Total Hydrocarbon Analyzer Installation
Teledyne Analytical Instruments 21
background gas.
Relay is ENERGIZED when the background gas
selection is O2, DE-ENERGIZED when the
background gas selection is N2.
Note: The polarity of this relay can be reversed using the A2
Match/A2 Invert function available from the Background
Gas display menu. See Section 4.7.2.3.
Table 3-4: Alarm Relay Contact Pins
Pin Contact
45 Threshold Alarm 1, normally closed contact
28 Threshold Alarm 1, moving contact
46 Threshold Alarm 1, normally open contact
42 Background gas selection, (normally closed contact)
44 Background gas, moving contact
43 Background gas selection, (normally open contact)
36 System Alarm, normally closed contact
20 System Alarm, moving contact
37 System Alarm, normally open contact
3.3.3.6 B ACKGROUND G AS S ELECTION AND D IGITAL R EMOTE
C AL I NPUTS
Background Gas Selection
When Background Gas is set to Auto (see Section 4.7.2), the 0-24 V
input formerly used for the Remote Zero command will be used to
select the background gas as follows:
Voltage Gas Selected
0V N
2
selected
24V O
2
selected
The background gas selection inputs (formerly digital remote zero
input) accepts 0 V (off) or 24 VDC (on) for automatic control of the
background gas switching. The customer will provide a signal that is