1

Lab Manual

RTD PT-100Platinum Resistance Temperature Detector - 100 Ohm at 0oC

Prepared by

Tam Hai-Dang Nguyen

ElectroMechanical Energy Laboratory

April 2013

2

Contents

1. Introduction.............................................................................3

2. Circuit board ...........................................................................4

3. Data acquisition system ..........................................................8

4. Procedure ..............................................................................10

Appendix - PT100 Temperature / Resistance Table ..................13

3

1. Introduction

This manual will introduce you to the PT100 and describe its function so you

can make the best use of your new instrument.

Product specification:

1. Body is ceramic

2. Temperature range: -200 oC to 350 oC

3. Size: Ф1.5 x 16(L) mm

4. Order: http://shop.cpu.com.tw/product/8798/info/

Circuit Schematic:Figure 1

Figure 2

4

2. Circuit board

Simulation of the circuit in Proteus software:

Varistors RVA and RVB are used to control the output voltage at pin 7 of LM324.

Using negative feedback (non-inverting amplifier)

1 fout in

g

RV V

R

(1)

Figure 3

Pin7

RVA RVB

Voutput

LM324

Figure 4

5

The output voltage of the circuit equals: (Tam figured out by experiment)

100( )output PT RA RBV V V k (2)

The linear properties of RTD PT100:

Calibration: by adjusting the varistors RVA RVB (see figure 3), we can make the

voltage line pass through desired values (0.25V at 25oC, 0.9V at 90oC). Then, reading

temperature (T) of PT100 will correspond to the output voltage (Vout):

T = 100*Vout

Figure 5

Figure 6

6

The completed circuit board in cover box:

6 mm

RB RA

Power LED

Power LED

power jack

Power (+)Power (-)

Output (+)Output (-)

BNC adapter

PT100

PT100

Figure 7

Figure 8

7

Specification:

1. Power supply: 7-15 V plug in 6 mm jack or power jacks (+)/(–)

2. Power LED indicator

3. 2 output ways: outputs (+)/(–) or BNC adapter

The construction of a ceramic PT100:

Measuring temperature by PT100’s body is better than by its tip.

To get the accurate temperature of the object, there should be a layer of thermal

grease (also called thermal paste, thermal compound) between PT100’s body and

object’s surface.

PT100

Object

Figure 10

Figure 9

8

3. Data acquisition system

DAQ software: LabVIEW with NI-9234 card

(4-Channel, ±5 V, 24-Bit, IEPE and AC/DC Analog Input Module)

DAQ system:Figure 11

Figure 12

9

The user interface in LabVIEW:

The block diagram:

Measure temperature of 3 channels.

DAQ assistant block reads voltages from 3 PT100 boxes, plots them in graph

and writes to 3 data files (temp1.lvm, temp2.lvm, temp3.lvm) in the same folder.

Temperature T [oC] = 100*Vchannel

Figure 13

Figure 14

10

4. Procedure

1. Connect PT100 boxes to NI-9234 (see figure 8 on page 6).

- option 1: using output(+) and output(–).

- option 2: using BNC connection.

2. Use USB communication between NI-9234 card and computer.

3. Start LabVIEW program, configure DAQ assistant block (config. steps in the

following).

4. Run the program: 2 options

- normal run: collect data, plot graph and write to files (*.lvm).

- run continuously: for testing.

Configuration steps:

1. Add a voltage channel, select an analog input from ai0 to ai3.

Voltage

11

2. Signal input range is ±5 V.

3. Coupling mode is DC.

4. Acquisition mode is N samples.

5. Rate (Hz) equals 10k.

6. Samples to read equals running time x rate (set 10k if 1s run).

ai0 to ai3

Signal rangeCoupling mode

Acquisition mode Samples to readRate (Hz)

12

7. Advanced Timing tab: set timeout value ≥ running time.

Timeout (s)

13

Testing reading temperature of hot water with 3 PT-100:

1. Pour hot water into a cup.

2. Use reading temperature of IR camera as reference (72.5oC).

3. Do all procedure steps, normal run, sampling time equals 12s.

4. Temperature T [oC] = 100*Vchannel = 100* 0.73 = 73

14

Appendix - PT100 Temperature / Resistance Table

15