Caractéristiques des accessoires d'assemblage de sonde de capteur PT100

RTD Pt100 Sensor features
The Pt100 Sensor probe is the most widely used type of resistance temperature detector (RTD = Resistance Temperature Detector), and like all resistance thermometers, it uses electrical resistance to measure temperature. Ainsi, a resistance thermometer does not directly show temperatures, but the amount of resistance in ohms as a function of temperature.
Platinum is the main primary material used in high-precision resistance temperature sensors, including the Pt100 sensor. The Pt100 Resistance Thermometer is the most widely used temperature probe in manufacturing process control because it covers a wide temperature range from -200 ° C à +850 °C and boasts good measurement accuracy and repeatability, which is also a prerequisite for laboratory measurements.
For these reasons, the Pt100 Sensor probe is often preferred over the thermocouple.
The Pt100 Sensor probe has a resistance of 100 ohms at 0 °C and 138.5 ohms at 100 °C. Its resistance varies linearly with temperature, c'est à dire., as temperature increases, so does the resistance of the Pt100; therefore, if we can measure resistance, we can determine temperature.

The pt100 temperature sensor is an instrument that converts temperature variables into a transmittable standardized output signal. Mainly used for measurement and control of temperature parameters in industrial processes. A transmitter with a sensor usually consists of two parts: the sensor and the signal converter. The sensor is mainly a thermocouple or a thermal resistor; the signal converter is mainly composed of a measuring unit, a signal processing and a conversion unit (since industrial thermal resistors and thermocouple scales are standardized, signal converters are also called Transmitter), some transmitters have added display units, and some also have fieldbus functions.

RTD PT100 Temperature Sensor Probe – 3-Wire Digital Stainless Steel 4x30mm Temperature Sensor 2m/78.74in Long – Measure Range -50°C to 200°C – Étanche, Oil-Proof and Anti-Corrosion

RTD Pt100 Temperature Sensor 2m Cable Stainless Probe 100mm 3 Wires -50~450 ℃

Sonde de capteur de température RTD PT100 3 Wires 2M Cable Thermocouple 1/2″ BSP Thread

Output signal of pt100 temperature sensor
If the pt100 temperature sensor is composed of two sensors used to measure the temperature difference, there is a given continuous functional relationship between the output signal and the temperature difference. There is a given continuous functional relationship between the pt100 temperature sensor output signal and the temperature variable (usually a linear function). The early production of PT100 temperature sensor has a linear functional relationship between its output signal and the resistance value (or voltage value) of the temperature sensor. The standardized output signals are mainly DC signals of 0mA~10mA and 4mA~20mA (or 1V~5V). Other standardized output signals with special provisions are not excluded. Temperature transmitters can be divided into two-wire systems and four-wire systems according to the power supply wiring method. The transmitters include electric unit combination instrument series (DDZ-Ⅱ type, DDZ-Ⅲ type and DDZ-S type), miniaturized modular type and multi-functional intelligent type. The former does not have a pt100 temperature sensor, and the latter two types of transmitters can be easily combined with thermocouples or thermal resistors to form a sensor-equipped transmitter.

Measurement method of pt100
Constant current and constant voltage method
In traditional instrumentation, this method is generally used. After constructing the constant current or constant voltage method, use Ohm’s law to calculate the resistance value of Pt100, and then query the graduation table to obtain the temperature. This method is the simplest and most versatile.
Universal Sensor Interface UTI method
Although the traditional method is simple, it has many shortcomings. Using a universal sensor interface chip, only a temperature-insensitive reference resistor is required. By connecting Pt100 to the UTI circuit, the ratio between Pt100 and the reference resistor can be obtained through the MCU, thereby obtaining the resistance value and temperature. This approach works well for microprocessor (MCU)-based systems. All UTI information is output only through an MCU-compatible signal, which greatly reduces external wiring and couplers between discrete modules.
un) Wiring diagram for connecting 1 Pt100__
b) Wiring diagram for connecting 2 à 3 Pt100_______
c) Wiring diagram for connecting 8 Pt100__

Pt100 tolerance classes
The tolerance class of a Pt100 probe indicates the accuracy with which the sensor can measure the temperature defined by the IEC 60751 standard.
The most common accuracy (tolerance) classes for Pt100 probes are class AA, UN, B and C.
Class AA has a tolerance of ±0.10 °C at 0 °C and ±0.53 °C at 250 °C.
Class A has a tolerance of ±0.15 °C at 0 °C and ±1.05 °C at 450 °C.
Class B has a tolerance of ±0.3 °C at 0 °C and ±3.3 °C at 600 °C.
Class C has a tolerance of ±0.6 °C at 0 °C and ±6.6 °C at 600 °C.
There are also more accurate accuracy (tolerance) classes, tel que 1/5 DIN or 1/10 DIN constructed as fractions of the B tolerance class values
Cependant, these tolerance classes are less common and are usually more expensive than classes A, B and C. En outre, to ensure such a precise tolerance class they have narrow fields of use.

RTD Pt100 sensor wiring
A resistive temperature sensor such as the resistance thermometer can be connected to the readout instrumentation with 2, 3 ou 4 wires.
The choice of connection depends on the degree of accuracy required in temperature measurement and the type of process application.

2-wire Pt100 RTD Sensor
The 2-wire Pt100 is the least accurate as the resistance of the connection cable adds up as an error to the measurement of the resistance at the temperature detected.
As mentioned, this type of connection does not compensate for the resistance of the connecting cable, which can greatly affect the measurement reading, to a greater extent as the cable length increases.
The 2-wire Pt100 is the simplest configuration but less accurate and reliable than the 3-wire Pt100 and 4-wire Pt100. It is usually used with short leads or where high accuracy is not required.

3-wire Pt100 Sensor RTD
To compensate for the added resistance, a second platinum wire is added to the sensor at the third lead.
The third lead is used to determine the lead resistance itself, which is subtracted from the overall measurement resistance, providing the true resistance due to temperature change alone.
The requirement is that the diameter of the conductors, and therefore their resistances, are the same, as is assumed from a 3-wire connection.
In other words, the 3-wire Pt100 is a resistance thermometer that uses three wires to connect the sensor to the reading instrumentation, allowing for compensation of variations in the electric cable.
The 3-wire Pt100 is the most used in industrial applications where the temperature measurement accuracy is better than the 2-wire Pt100, but less precise and reliable than the 4-wire Pt100.

4-wire Pt100 Sensor RTD
The 4-wire Pt100 resistance thermometer is very precise and is often used in laboratories, to measure the temperature of fluids and gases and where maximum reading accuracy is required.
The 4-wire Pt100 differs from the 3-wire Pt100 due to the presence of an additional wire for each pole of the sensor. These compensation wires eliminate the effect of variations in the electrical wires that carry the signal to the reading instruments.
Therefore the 4-wire Pt100 resistance thermometer is more accurate and reliable than the 3-wire Pt100 because of the compensation of the resistances of the wires used for measurement.