Almost all DC railways use rail as the return channel of working current. The rails are mounted on wooden or concrete sleepers and in good contact with the soil. The conductive soil electrolyte is in parallel with the guide rail. The basis of the railway network is the whole length. This relationship and the risk of corrosion are well known. Stray current generated by railway facilities must be minimized through appropriate design and management measures. However, since stray current cannot be avoided completely, it is better to take additional protection measures for pipes and cables, which is necessary in many cases.
The resistance load of welded rail is far less than that of groove joint rail. However, it is necessary to use longitudinal wiring to make jumpers at switching points and intersections.
Measures to reduce stray current are as follows:
1. The railway network is completely interconnected;
2. Good electrical insulation between railway and soil;
3. Small power supply.
The leakage load of ballasted wooden sleeper track is relatively low, which is only 1% of the leakage load of directly buried track. However, good electrical insulation can only be achieved by ensuring that there is no electrical contact between the rail and other equipment with low ground resistance.
In principle, overhead poles are not connected to the track. The only exception is that the electrical equipment on the overhead conductor pole is connected to the rail. In case of fault, it is possible to avoid high contact voltage which is not allowed. The overhead conductor pole should be insulated from the foundation and have a high enough grounding resistance.
Rails on bridges are usually electrically connected to steel or concrete members, which have low ground resistance. In the new device, according to the grounding resistance of the components and the type of track subgrade, these track and bridge elements are required to be electrically insulated.
In addition, metallic sheaths of pipes and cables shall be electrically insulated from these parts at all times to prevent stray currents from the rails being transmitted directly to these conductors.
Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services. Tel: 0539 3712117, 15588026668.