2 / 3 wire PT100 Temperature Sensor Probe

RS pro rtd 2/3/4 wire pt100 ohm Temperature Sensor Wiring harness, resistance temperature detector. 2 npt platinum resistance thermometer stainless steel probe, Fast response, high temperature resistance, waterproof characteristics.

PT100 sensors usually use three-wire connection. Two of the lines can be understood as straight-through, and the resistance in the middle is 0 ohms (call these two lines B and C lines). As for the last line (called line A), between A and B/C, the resistance is about 110 ohms at room temperature. Generally, meters or collectors provide terminals for three-wire connection (although it can be understood that the B/C line is a direct connection, it must be connected). There are also a small number of devices that use four-wire connection or two-wire connection. The accuracy is also the higher the number of lines, the higher the accuracy. The three-wire connection method usually uses a bridge to ensure the accuracy of the test results.

Pt100 is a platinum thermal resistor, its resistance is proportional to the change of temperature. The relationship between the resistance of PT100 and temperature change is: when the temperature of PT100 is 0℃, its resistance is 100 ohms, and at 100℃, its resistance is about 138.5 ohms. Its industrial principle: When the PT100 is at 0 degrees Celsius, its resistance is 100 ohms, and its resistance will increase at a constant rate as the temperature rises.

Application of Pt100 temperature sensor
The isolation transmitter is a hybrid integrated circuit that converts the thermal resistance signal into a linear standard signal according to the temperature. This circuit integrates a set of multi-channel highly isolated DC/DC power supplies, several high-performance signal isolators and thermal resistor linearization, long-line compensation, and interference suppression circuits on the same chip. Especially suitable for Pt100/Cu50 thermal resistance signal isolation and conversion into standard signals, temperature signal transmission and distortion-free remote transmission. Temperature signal acquisition and isolation of industrial field PLC or DCS systems.
The chip integrates a high-efficiency DC-DC, which can generate two sets of mutually isolated power supplies to supply power to the internal input amplification circuit, modulation circuit, and output demodulation circuit, conversion circuit, and filter circuit respectively. The SMD process structure and new technology isolation measures enable the device to achieve: 3000VDC triple isolation of power supply and signal input/output. And it can meet the industrial-grade harsh working environment requirements of wide temperature, humidity and vibration.
The temperature signal isolation amplifier is very easy to use and requires only a few external components to achieve the isolation and transmission of Pt100 thermal resistance signals. And can realize the functions of one in and two out, one in and four out for industrial site temperature control signals.

PT100 cable wiring method
PT100 thermal resistor is the main component that converts temperature changes into resistance value changes. It is usually necessary to transmit the resistance signal to the computer control device or other primary instruments through the leads. Industrial thermal resistors are installed at the production site at a certain distance from the control room. Therefore, the lead of the thermal resistor will have a greater impact on the measurement results.

There are three main wiring methods for the PT100 thermal resistor wire harness:
2-wire wiring harness: The method of connecting a wire to both ends of the thermal resistor to draw out the resistance signal is called a two-wire system. This lead method is very simple, but because the connecting cable must have lead resistance r, the size of r is related to the material and length of the wire. Therefore, this cable connection method is only suitable for occasions with low measurement accuracy.

3-wire wire harness: The method of connecting one lead to one end of the root of the PT100 thermal resistor and two leads to the other end is called a three-wire system. This method is usually used in conjunction with a bridge, which can better eliminate the influence of lead resistance and is the most commonly used lead resistance in industrial process control.

4-wire sensor harness: The method of connecting two wires at both ends of the root of the PT100 thermal resistor is called a four-wire system. Two of the leads provide a constant current I for the thermal resistor, convert R into a voltage signal U, and then lead U to the secondary instrument through the other two leads. It can be seen that this lead method can completely eliminate the resistance influence of the lead and is mainly used for high-precision temperature detection.
PT100 thermal resistance adopts three-wire connection method. The three-wire system is used to eliminate measurement errors caused by the resistance of the connecting wires. This is because the circuit used to measure thermal resistance is generally an unbalanced bridge. The thermal resistor is an arm resistor of the electric bridge, and its connecting wire (from the thermal resistor to the central control room) also becomes part of the bridge arm resistor. The resistance of this part is unknown and changes with the ambient temperature, causing measurement errors. Using a three-wire system, connect one wire to the power end of the bridge, and the other two wires to the bridge arm where the thermal resistor is located and the adjacent bridge arm. This eliminates measurement errors caused by wire line resistance. In industry, the three-wire connection method is generally adopted.