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Dec 29, 2017


PT100 working principle

How it works: When the PT100 at 0 degrees Celsius when his resistance is 100 ohms, its resistance will rise as the temperature increases from nearly uniform. But the relationship between them is not simply proportional to the relationship, but should be closer to a parabola.

Platinum resistance of the resistance changes with temperature changes in the formula:

(T-100) t & lt; / RTI & gt; t & lt;

0 & lt; t & lt; 850 ° C Rt = R0 (1 + At + Bt2)

Rt is the resistance at t ℃, R0 is 0 ℃ when the resistance. The formula A, B, coefficient for the experimental determination. Here is the standard

DIN IEC751 Coefficient: A = 3.9083E-3, B = -5.775E-7, C = -4.183E-12

According to Vader formula to obtain the resistance is greater than or equal to 100 ohms Rt -> t conversion formula:

0 ≤ t & lt; 850 ° C t = (sqrt ((A * R0) ^ 2-4 * B * R0 * (R0 - Rt)) - A * R0) / 2 / B / R0

PT100 temperature sensor is a platinum (Pt) made of resistive temperature detector, is a positive resistance coefficient, the resistance and temperature changes in the relationship is as follows: R = Ro (1 + αT) where α = 0.00392, Ro (Resistance value at 0 ℃), T is Celsius temperature. Therefore, platinum-made resistance temperature detector, also known as PT100.

1: Vo = 2.55 mA × 100 (1 + 0.00392T) = 0.255 + T / 1000.

2: When measuring Vo, do not separate any current, otherwise the measured value will not be allowed. Circuit analysis Since the general power supply more parts, the power supply is with the noise, so we use zener diode as regulator parts, the role of the 7.2V zener diode, making the 1K resistor and 5K variable resistor The voltage and the 6.5V, 5K variable resistor on the adjustment of the transistor can determine the radio (collector) pole current, and we must be set to 2.55mA collector current, making the measurement voltage V as shown by the arrow to 0.255 + T / 1000. Subsequent non-inverting amplifier, the input resistance is almost infinite, but also amplified 10 times, making the output of the op amp 2.55 + T / 100.6V Zener diodes such as the role of 7.2V zener diode, We use it to call out 2.55V, so the voltage follower output voltage V1 is also 2.55V. Then, the output of the differential amplifier is Vo = 10 (V2-V1) = 10 (2.55 + T / 100-2.55) = T / 10, and if the current room temperature is 25 ° C, the output voltage is 2.5V. [1] 

Curve chart

PT100 / PT1000 platinum resistance RT curve chart

Indexing table of PT100

-50 degrees 80.31 ohms

-40 degrees to 84.27 ohms

-30 degrees 88.22 ohms

-20 degrees 92.16 ohms

-10 degrees 96.09 ohms

0 degrees 100.00 ohms

10 degrees 103.90 ohms

20 degrees 107.79 ohms

30 degrees 111.67 ohms

40 degrees 115.54 ohms

50 degrees 119.40 ohms

60 degrees 123.24 ohms

70 degrees 127.08 ohms

80 degrees 130.90 ohms

90 degrees 134.71 ohms

100 degrees 138.51 ohms

110 degrees 142.29 ohms

120 degrees 146.07 ohms

130 degrees 149.83 ohms

140 degrees 153.58 ohms

150 degrees 157.33 ohms

160 degrees 161.05 ohms

170 degrees 164.77 ohms

180 degrees 168.48 ohms

190 degrees 172.17 ohms

200 degrees 175.86 ohms


Common pt100 temperature sensing elements are ceramic components, glass components, mica components, which are separated by platinum wire around the ceramic framework, glass skeleton, mica frame and then processed through a complex process


Medical, electrical, industrial, temperature calculation, resistance calculation and other high-precision temperature equipment, the scope of application is very wide.

Thin film platinum resistance

Film Platinum Resistance: Platinum is sputtered on a ceramic substrate with a film thickness of less than 2 microns by vacuum deposition. The Ni (or Pd) leads are fixed with a glass frit and laser-tempered to form thin film elements.

Temperature Sensor

PT100 thermal resistance of the temperature value and the relationship between changes in resistance, people will use it to the characteristics of research and development and production of the PT100 RTD temperature sensor.

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