Teledyne 3300TB - Low cost trace oxygen analyzer - Manual (Page 20)

3 Installation Model 3300 TB
3-4
Teledyne Analytical Instruments
Analog Outputs: There are three DC output signal connectors with
screw terminals on the panel. There are two wires per output with the polar-
ity noted. See Figure 3-3. The outputs are:
0–10 V % Range: Voltage rises with increasing oxygen concentration,
from 0 V at 0 percent oxygen to 10 V at full scale
percent oxygen. (Full scale = 100% of programmed
range.)
0–10 V Range ID: 03.33 V = Low Range, 06.66 V = High Range,
10 V = Air Cal Range.
4–20 mA % Range: Current increases with increasing oxygen concentra-
tion, from 4 mA at 0 percent oxygen to 20 mA at full
scale percent oxygen. (Full scale = 100% of pro-
grammed range.)
Alarm Relays: The three alarm-circuit connectors are screw terminals
for making connections to internal alarm relay contacts. There is one set of
contacts for each type of alarm. Contacts are Form C, with normally open
and normally closed contact connections capable of switching up to 0.5
ampere at 125 VAC into a resistive load (2A for 30 VDC).
The alarm relay circuits are designed for failsafe operation, meaning the
relays are energized during normal operation. If power fails the relays de-
energize (alarms activated).
The contact connections are indicated diagrammatically on the rear
panel as Normally Closed, Common, and Normally Open. Figure 3-2
explains how these act in failsafe operation.
Alarm 1 and Alarm 2 can both be configured as either HI or LO. A
HI alarm will activate when concentration is above treshold, while a LO
alarm will activate concentration is below treshhold.
Figure 3-2: Contact ID for FAILSAFE Relay Operation