1. Not easily affected by parasitic thermocouples and resistance drop and temperature drift along the wire, transmission lines can use very cheap and thinner twisted pair wires;

2. When the output resistance of the current source is large enough, the voltage induced in the wire loop through magnetic field coupling will not have a significant impact because the current caused by the interference source is extremely small. Generally, twisted pair cables can be used to resist and reduce interference;

3. Capacitive interference can cause errors related to receiver resistance. For a 4-20mA two-wire loop, the receiver resistance is usually 250 Ω (sampling Uout=1-5V), which is small enough to produce significant errors. Therefore, the allowable wire length is longer and farther than that of a voltage telemetry system;

4. Each individual reading device or recording device can be switched between different channels with varying lengths of wires, without causing differences in accuracy due to differences in wire length;

5. Using 4mA for zero level makes it very convenient to determine open circuit or sensor damage (0mA state).

6. It is easy to install surge and lightning protection devices at the two-wire output port, which is beneficial for safe lightning protection and explosion prevention.

2、 Precautions for using temperature transmitter:

1. The power supply of the temperature transmitter should not have spikes, and the calibration of the transmitter should be carried out 5 minutes after power on, and attention should be paid to the ambient temperature at that time.

2. Do not open the cover of the digital transmitter at will to avoid moisture.

3. The shell should be firmly grounded, and power and signal output should be transmitted using shielded cables. The crimping nut should be tightened to ensure airtightness.

4. Be sure to use a wrench or other tool to tighten the nut during installation, and do not directly twist the meter head by hand to prevent breaking the internal circuit. To adjust the display direction, first loosen the "header fixing screws" on both sides, gently rotate them to the appropriate position (not exceeding 270 ℃), and then tighten the screws.