Urgent stray current mechanism, what is stray current Introduction to stray current

1. Stray current refers to the current that flows outside the designed or specified circuit, also known as "lost current". It flows in the soil and is not related to the piping system being protected. This current enters the pipeline from a certain part of the pipeline B, this part is called the cathode, and after the current flows along the pipeline for a certain distance, it flows out of the pipeline C, this part is called the anode, where the pipeline produces anodic oxidation, that is, stray current corrosion.

2. Stray current corrosion is essentially electrochemical corrosion, and anodic corrosion is more serious. The overview diagram takes a DC traction system as an example.

Answer] :(1) DC stray current caused by DC overhead electric locomotive; (2) The leakage current that occurs after the damage to the surface of the cable may also produce stray current; (3) The AC stray current is generally small, but when the electrical traction trap network is AC and the neutral line of the power transformer is grounded, the AC stray current generated is enough to detonate the electric thunderbolt beam; (4) The stray current of metal-free objects, mainly the natural current of the earth, whose value is much smaller than the safe current of the detonator, and there is no change before and after the power failure; (5) The stray currents that threaten the security of the electric explosion network are mainly distributed between the conductors, among which the air duct is the largest to the rail, followed by the slag is the air duct to the rock mass and the rail to the rock mass.

As shown in Figure 2-1, because the running rail cannot be completely insulated from the ground, some current leaks from the running rail to the ground, and the traveling rail is at the anode of the corroded battery and is easily corroded. The data show that the stray current corrosion of the track is more obvious in the tunnel and the fork, and in some places it is necessary to re-track in 2 3 years.

The corrosion of the running rail and its accessories generally occurs on the contact surface with other objects, and these corrosions are difficult to detect from the outside, and when they are found, the rail needs to be replaced, etc., so it is very harmful. When the buried pipeline and the high-voltage AC transmission line are close to or cross, the current generated by the AC transmission line generates an induced voltage on the pipeline through magnetic coupling, so that the potential of the pipeline to the ground is not zero. If the pipeline voltage is too high, it may pose a threat to the personal safety of operators and maintenance personnel.

In the subway system, when the traction current is not well flowed back and a large amount of stray current flows into the ground, the voltage between the rail and the structural reinforcement will rise, which poses a threat to the personal safety of platform passengers. When the line is introduced into buildings such as operation warehouse, repair warehouse and traffic inspection warehouse, if the insulation construction is poor, a certain degree of electrical connection will occur between the rail and the building, so that the leakage current will become larger, and the stray current corrosion will be extremely violent.