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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 35 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 Two-Wire RTD Transmitter will produce a standard 4-20mA output
signal proportional to that produced by its RTD input temperature sensor.
Transmission of the proportional current output may be accomplished by
using inexpensive copper wire. The RTD transmitter accepts two-wire or
three-wire ohm platinum RTD sensors (PT100,alpha = 0.00385).

1

Summary of Contents for TX94A

Page 1: ...e mail info omega com For latest product manuals www omegamanual info TX94A Ultra Miniature Temperature Transmitters TM Shop online at omega com User sGuide ...

Page 2: ...specifications without notice omega com info omega com Servicing North America U S A Omega Engineering Inc Headquarters Toll Free 1 800 826 6342 USA Canada only Customer Service 1 800 622 2378 USA Canada only Engineering Service 1 800 872 9436 USA Canada only Tel 203 359 1660 Fax 203 359 7700 e mail info omega com For Other Locations Visit omega com worldwide ...

Page 3: ...ns 1 1 3 General Description 2 1 4 Features 2 1 5 Models Available 3 Section 2 Installation 2 1 Mounting 4 2 2 Wiring 5 Section 3 Calibration Instructions 3 1 Equipment Required 6 3 2 Set up of Equipment 6 3 3 Calibration Procedures 7 Section 4 Troubleshooting Guide 8 Section 5 Specifications 9 ...

Page 4: ... 2 Figure 2 1 Assembly inside a Protection Head 4 Figure 2 2 Wiring Diagram for RTD Transmitter 5 Figure 3 1 Transmitter Calibration Set Up 7 Figure 5 1 Dimensions 9 Table 1 1 Range Code 3 Table 1 2 Model Numbers 3 Table 3 1 Calibration Values 7 ...

Page 5: ... 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 wir...

Page 6: ...ransmitter The transmitter works with 2 or 3 wire RTDs and provides an output current of 4 20mA proportional to the RTD Sensor When the transmitter is mounted inside a protection head see Figure 2 1 two copper wires now carry the temperature signal and dc voltage to operate the transmitter thereby reducing possible noise pick up errors The transmitter does NOT provide isolation between its input a...

Page 7: ... 120 F 40 to 49 C 1 0 to 200 F 18 to 93 C 2 0 to 300 F 18 to 149 C 3 0 to 500 F 18 to 260 C 4 0 to 750 F 18 to 399 C 5 0 to 1000 F 18 to 538 C 6 Table 1 2 Model Numbers Model Number Description TX94A RTD Transmitter 100 ohm Pt alpha 0 00385 Insert range code from Table 1 1 ...

Page 8: ...ounting The transmitter may be 1 surface mounted 2 mounted inside a protection head shown in Figure 2 1 Figure 2 1 Assembly of the Transmitter inside an PR 14 Protection Head SECTION A A POWER LINES RTD WIRES ...

Page 9: ...the PS and PS power terminals Note that the load usually a monitoring instrument may be connected to either the or power lead 2 Connect the RTD element to the IN and IN input terminals Figure 2 2 Wiring Diagram for RTD Transmitter 3 WIRE RTD RED BLACK RED BLACK JUMPER WIRE BLACK 2 WIRE RTD ...

Page 10: ...s for the Z zero and S span adjustments that correspond to the model number For example for Model TX94A 2 the Z value is 92 95 ohms and the S value is 135 84 ohms If a Thermocouple RTD Simulator is used such as the Model CL511 Precision Calibrator select the Temperature Input Z zero and S span values 3 Set the Decade Box to the selected Z zero ohmic value Adjust the Z potentiometer to read 4 000 m...

Page 11: ...el Alpha 0 00385 Zero Span TX94A Zero Span 40 120 F 1 84 27 119 01 0 200 F 2 92 95 135 84 0 300 F 3 92 95 156 94 0 500 F 4 92 95 197 69 0 750 F 5 92 95 246 69 0 1000 F 6 92 95 293 46 COPPER WIRE RTD CALIBRATOR CL511 DECADE RESISTANCE BOX EITHER OR ZERO SPAN With 250 Ohm Load dc Supply must be at least 12 35 Vdc DC SUPPLY 8 35 Vdc DMM 4 20 mA MONITOR 250 Ohms ...

Page 12: ...on the power supply a Measure the total resistance of each device excluding the transmitter and power supply in the 20 mA loop including the resistance of the lead wires b Calculate maximum allowable loop resistance using the formula Loop Resistance maximum Vsupply 8 V 0 020A For example a 24V power supply would give a maximum loop resistance of 16 V 0 020A 800 ohms c Make sure the power supply is...

Page 13: ...Range 25 Power Supply Voltage Operating Range 8 Vdc to 35 Vdc 28 mA max required per transmitter Accuracy 0 1 of full scale includes effects of hysteresis and repeatability Frequency Response 3dB 3Hz Thermal Zero Shift 0 01 F of span span 10 mV 0 02 F of span 4 10 mV span Thermal Span Shift 0 01 F of span 0 93 23 6 MAX 0 52 13 2 0 480 12 19 0 480 12 19 0 156 3 96 for 6 32 SCREW 2 PLCS 0 250 6 35 1...

Page 14: ...an 4 20 mA dc Current Output Limits 3 to 28 mA typical Max Loop Resistance Vsupply 8V 0 020A ohms Load Resistance Effect 0 01 of span per 300 ohms change Power Supply Effect 0 002 of output span per volt Input Sensor 2 or 3 wire RTD Max Bridge Current 0 8 mA ...

Page 15: ...GA if the unit is found to be defective it will be repaired or replaced at no charge OMEGA s WARRANTY does not apply to defects resulting from any action of the purchaser including but not limited to mishandling improper interfacing operation outside of design limits improper repair or unauthorized modification This WARRANTY is VOID if the unit shows evidence of having been tampered with or shows ...

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