(1) Electrostatic induction

(2) Electromagnetic induction

(3) Leakage current induction

2) Additional thermoelectric potential and chemical potential.

3) Vibration.
When a wire moves in a magnetic field, it generates an induced electromotive force. Therefore, it is necessary to secure the signal wires in a vibrating environment. The above four types of interference are all connected in series with the signal, that is, they appear in the form of series-mode interference.

4) Interference caused by different ground potentials.
In the earth, there are often potential differences between different points. Especially near high-power electrical equipment, when the insulation performance of these equipment is poor, this potential difference is even greater. In the use of instruments, there are often more than two ground points in the input loop intentionally or unintentionally. This will introduce the potential difference of different grounding points into the instrument. This ground potential difference can sometimes reach more than 1 to 10 volts. It appears on the two signal wires at the same time. Through electrostatic coupling, a common voltage to ground can be induced at the two input terminals, which appears in the form of common mode interference. Since common mode interference does not superimpose with the signal, it does not directly affect the instrument. However, it can form a leakage current to the ground through the measurement system. This leakage current can directly act on the instrument through the coupling of the resistor, causing interference.

5) Radio frequency interference

6) Others