Omega TX90A Series User manual

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TX91A
(J, K, T, E) 4-20 mA
Mini Temperature Transmitter
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User’s Guide
TM

The information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains, and reserves
the right to alter specifications without notice.
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i
TTAABBLLEEOOFFCCOONNTTEENNTTSSPPAAGGEE
1.0 GETTING STARTED. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Unpacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Safety and EMC Considerations . . . . . . . . . . . . . . . . . . . . 1
1.3 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.4 Available Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.5 Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.6 Shock Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.0 CONNECTING POWER AND SIGNAL INPUTS. . . . . . . . . 4
3.0 CALIBRATING THE TRANSMITTER. . . . . . . . . . . . . . . . . 6
4.0 SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
LIST OF FIGURES AND TABLES
Figure 2-1 Power Input Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 2-2 Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Figure 3-1 Calibration Setup using a Millivolt Source . . . . . . . . . . . . . 6
Figure 3-2 Calibration using a Thermocouple Simulator . . . . . . . . . . . 7
Figure 4-1 Case Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 4-2 Transmitter Block Diagram . . . . . . . . . . . . . . . . . . . . . . . 11
Table 1-1 Range/Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Table 2-1 Screw-Terminal Pin Assignment . . . . . . . . . . . . . . . . . . . . 5
Table 3-1 Fahrenheit Temperature to Millivolt Conversion Chart . . . . 8
Table 3-2 Celsius Temperature to Millivolt Conversion Chart . . . . . . . 9

ii

SECTION 1 GETTING STARTED
1.1 Unpacking
Remove the packing list and verify that you have received all equipment. If you have
any questions, contact the nearest Customer Service Department, as listed on the
cover of this manual.
Upon receipt of shipment, inspect the container and equipment for any signs of
damage. Note any evidence of rough handling in transit. Immediately report any
damage to the shipping agent.
Note: The carrier will not honor any claims unless all shipping material is saved for
their examination. After examining and removing contents, save packing materials
and carton in the event reshipment is necessary.
1.2 Safety and EMC Considerations
This instrument is a Class III device (8 to 50 Vdc).
Always use a power supply, which complies with EN 60950 safety standard.
••Do not expose the transmitter to rain or condensing moisture.
••Do not operate the transmitter in flammable or explosive atmosphere.
••As with any electronic instrument, you may encounter high voltage exposure
when installing, calibrating or removing parts of the transmitter.
EMC Considerations
••Whenever EMC is an issue, always use shielded cables.
••Never run signal and power wires in the same conduit.
••Use signal wire connections with twisted-pair cables.
••Install Ferrite Bead(s) on signal wires close to the instrument if EMC problems
persist.
Failure to follow all instructions and warnings may result in injury!
1.3 General Description
The TX91A Series transmitter accepts thermocouple sensor types J, K, T, and E and
will produce a standard 4-20 mA output signal proportional to that produced by its
attached thermocouple millivolt input. The transmitter does NOT provide isolation
between its input and the 4-20 mA output; therefore, an ungrounded thermocouple
junction is suggested to prevent possible ground loops.
The transmitter provides cold reference junction compensation for the thermocouple
types as well as amplification, common-mode rejection and controlling the current
drawn from an 8-to-50 Vdc source to produce the 4-to-20 mA output signal. As
much as 800 ohms dropping resistance may be used in the power leads of the
TX91A when the unit is energized from a 24 Vdc source because of the small
compliance voltage needed by the unit.
1

1.4 Available Ranges
As specified in Table 1-1, the transmitter has 10 ranges. Depending upon the range,
the transmitter can measure temperature span as narrow as 160°F or as wide as
1000°F. A multi-turn, top-accessible potentiometer provides fine span tuning. A
second top-accessible, multi-turn potentiometer provides a zero adjustment which
allows placement of the 4-mA output temperature within +/- 25% for Fahrenheit and
+/- 10% for Celsius of nominal span (refer to Section 3.0, Calibrating the Transmitter,
for more details).
Table 1-1. Range/Models
RRaannggeeMMooddeell
0 to 200°FJ2K2T2E2
0 to 300°FJ3K3T3E3
0 to 500°FJ4K4T4E4
0 to 750°FJ5K5T5E5
0 to 1000°F J6 K6 N/A E6
-0 to 100°CJ7K7T7E7
-0 to 150°CJ8K8T8E8
-0 to 250°CJ9K9T9E9
-0 to 400°C J10 K10 T10 E10
-0 to 500°C J11 K11 N/A E11
2

1.5 Ordering Guide
The model number describes the functionality of the transmitter.
MMooddeellTTeemmppeerraattuurreeRRaannggee
* 0 to 1000°F ( 0 to 500°C) is not available for type T thermocouple.
**Factory Scaling available for additional charge. Consult factory.
To order additional transmitters, write TX91A followed by the model letter and number.
For example:
TX91A-J3 = Transmitter with thermocouple type J and a temperature range of -0 to 300°F.
TX91A-E9 = Transmitter with thermocouple type E and a temperature range of -0 to 250°C.
3
J
K
T*
E
2 -0 to 200°F
3 -0 to 300°F
4 -0 to 500°F
5 -0 to 750°F
6 -0 to 1000°F
7 -0 to 100°C
8 -0 to 150°C
9 -0 to 250°C
10 -0 to 400°C
11 -0 to 500°C
OPTION:
FS** Factory Scaling
TX91A-

4
1.6 Shock Resistance
Lightweight TX91A transmitter circuit boards are fabricated from rigid, shock resistant
materials with the components soldered to the circuit board.
The TX91A transmitter's small size permits mounting into thermowells or wall mount-
ing in confined areas.
SECTION 2 CONNECTING POWER AND SIGNAL INPUTS
••Verify that the transmitter is connected for the correct power voltage rating.
••The transmitter has no power on switch, so it will be in operation as soon as you
apply power.
Figure 2-1 Power Input Setup
+PS and -PS screws accept 2mm (13 gauge) or lighter wire. Input range is 8-50 Vdc.
DC SUPPLY
8--50 VDC
4--20mA
+IN
-IN
+PS
PS
R LOAD
TH RMOCOUPL
TRANSMITT R
1
25
4

5
SECTION 2 CONNECTING POWER AND SIGNAL INPUTS (continued)
Table 2-1. Screw-Terminal Pin Assignment
* For improved EMC performance, connect Pin 3 to Earth Ground.
Figure 2-2 Pin Assignment
12345
01
ZS
RANGE:
TYPE: JKTEP
02 03 04 05 06 07 08 09 10
IN IN PS
M
PS
1 + Thermocouple
2 - Thermocouple
3 * Earth Ground
4 +Power/Signal Output
5 -Power/Signal Output

6
3.0 CALIBRATING THE TRANSMITTER
Calibration Setup:
To prepare the ice bath:
1. Fill a glass beaker with crushed ice made from distilled water.
2. Fill the beaker with enough distilled water so that the ice bath just becomes
slush, but not enough to float the ice.
3. Insert the reference thermocouple.
Figure 3-1. Calibration Setup using a Millivolt Source
1
2
3
4
5
SPAN
(—)
(—)
(—)
(—)
(+)
(+)
(+)
(+)
DMM
(4-20 mA)
MONITOR
DC SUPPLY
24 VDC
MULTIVOLT
SOURCE
DMM
ZERO
INPUT
THERMOCOUPLE
WIRE
ICE BATH
COPPER
WIRE
REFERENCE
PROBE
250 OHMS