According to research, the accelerated destruction of the underground communications of metal is due to the occurrence of galvanic corrosion. Its cause is the purposeful movement of charged particles that are stray currents. This situation points to the fact that to ensure the safety of steel structures necessary to understand how to eliminate stray currents in underground pipes for water supply.
The definition
Stray currents - is charged elektrochastitsy a certain path of movement arising in the land, which is a conductor. The term wandering arose from the fact that it is impossible to predict the location of the particles and the beginning of the emergence process. Influence wandering elektrochastits extremely negative impact on metal objects, above ground and below.
Similar processes occur due to the growing number of electrified objects, which are the basis of modern countries. And since the ground conductor for electricity, there is an interaction between the elements.
Wandering like particles having electric, which requires to interact comparison of a voltage of 2 arbitrary points, only for the embodiment of vagus conductor - it land. As a result, the metallic material located near the process breaks down faster due to corrosion.
The process of forming
The reason for the occurrence of stray currents serves a large number of equipment working on the electric charge, resulting in potential sources are the following elements:
- in the presence of memory objects such as a substation HV zero conductor valves;
- emergence activity as a result of destruction of the insulating layers of wires carrying current in the cables and overhead networks, where neutral is isolated;
- presence binder technological link between the conductor and ground constructions with a grounded neutral and rail transport, the movable current.
The mechanism of occurrence of spontaneous discharges can consider an example of one of the following claims.
One end of the neutral conductor is connected to the power storage, and the other is connected to the bus PEN consuming energy having adjoining to the memory. This implies that the value of the electric potential difference between the terminals generates stray currents, as energy will be transferred to the memory, which in turn will form a chain.
In this case, the amount of the loss is not of great interest, as the pass along the path of low resistance, however, a certain portion will fall to the ground.
Similarly, leakage of energy occurs in the case of damage to the wiring insulation.
In this case, the constant uninterrupted leakage does not occur, because of its appearance signals the system and there is automatic localization section, and according to the regulations, there is a certain amount of time allotted to eliminate Troubleshooting.
Important! Coglasno statistics main space forming power and the leakage of stray currents education occur in urban and suburban areas where there is ground transportation, depending on the grid.
When using city electric transport, voltage is applied from the power substation in the traction system, passing on the rails and make the return cycle. If the rails as iron base with respect to the conductor are not sufficiently stable, it leads to the formation of ground locations stray currents, then any metal structure, which appeared on their way, for example, sanitary products, act as conductor.
Important! Such an interaction occurs due to the fact that moving current chooses the path of least resistance, which at the metal is lower than that of the earth.
All this will lead to the accelerated destruction of metal products.
Interconnection currents and corrosion processes
Any water in the soil is damaged by corrosion due to exposure to moisture and salts, but here even if the plug and current activity, then there is the electrolytic process. Thus on the electrochemical reaction rate affects the charge flowing between the anode and the cathode. Hence, the damage of the metal products will affect the activity of soil resistance to the movement of the charges, as well as the complexity of currents that are in the anodic and cathodic zone.
In such circumstances, the water supply system is subject to the usual corrosion under the influence of leakage currents. The impact creates a galvanic couple, accelerating corrosion development. In history there are many moments when stacking the pipeline had to be 20 years, but in fact the destruction occurred after 2 years.
Embodiments possible protection
To protect metal products from the harmful effects of different methods that can be divided according to the nature of their use in passive and active.
passive version
This embodiment is an application of a different insulating material forming the protection for the conductor to the metal. As the insulation is applied:
- epoxy resin mixture;
- inclusion in the polymer;
- a coating of bitumen.
However, if we restrict ourselves to this embodiment, the full protection does not work, since the insulating material is not wholly barrier due to the presence of diffusion permeability. Therefore, there is a partial isolation process. In addition, in the process of moving a fiber tubes may be damaged thereby causing significant scratches, notches, through holes and other flaws.
Important! Therefore, the use of passive protection method can be used only as a supplement.
active protection
It indicates the use of the active source localization method of exposure by applying cathodic polarization, where the natural negative charge shifts.
To realize such protection is necessary to use one of two tools:
- Electroplating method - the effect of the galvanic couples performed destruction of the sacrificial anode, thereby ensuring protection of metal structures. The method is active when the soil resistance of 50 ohms per meter, if no resistance following method is effective.
- DC power source - ensure the avoidance of dependence on the strength of the soil resistance. Cathodic protection is used, the source of which is enclosed in the formed converter connected to the AC circuit. Since the source specially formed through its regulation can set the desired current level of protection, depending on the circumstances.
Such a method can provide and negative effects:
- reprotected - exceeding the required capacity, the result is the destruction of metal products;
- incorrect calculation of protection - resulting in accelerated stress corrosion located near metal objects.
These examples can be considered for the protection of such a product as a heated towel rail.
Corrosion processes on such products or other endpoints water products have never happened, but it was actually before the application of multilayer pipes, where there is contact with the aluminum inside wall. As a result, the formation of stray elements occurs not only due to the use of plastic pipes in direct room, but in others, as in an apartment building, they can be applied with a neighbor another floor.
Important! To avoid the negative impact of the resulting currents need to own design equalize potentials, by providing a towel warmer, and water pipes battery element ground.
The use of so necessary grounding occurs in respect of any communication which is made of metal pipe, for example, a gas pipeline in the ground.
Rules of performance measurement
To assess the full extent of the situation with the leak electrocharge must perform a number of activities:
- measuring the voltage and current through the membranes aspiration line cables;
- detection of the potential difference between the contact rails and conduits located in the soil;
- level check rails isolation from the primer coating used for the experiments web portion;
- Score leakage power density with sheaths of cables in the ground.
To perform the measurements, a special device is used, if the event is held on the railroad tracks should be chosen the rush hour traffic.
To test transformers and substations are used in the line of motion - electrode coupled to the device, connected to the memory stick and 10 meters from the substation. The entire device is fixed difference arises.
If will laying line pipes for water supply is important to identify the location of stray currents, to this end, the difference potential between two sampling points of the earth surface, arranged perpendicularly to each other in compliance with equal distance. Such a definition is important to carry out systematically with a gap of one kilometer.
Thus consuming appliances must have precision class not less than 1.5, and the equipment from 1 Mohm resistance. Application of measuring electrodes the potential difference is higher than 10 mV. The time of one measurement necessarily takes place within 10 minutes, and the gap between the processes 10 seconds.
conclusion
The calculation of the capacity and determination of localization stray electric particles should not be neglected, as the quality of this work depends water supply system, but this should be used simultaneously two methods of protection, which will settle the arising tension and ensure complete protection pipeline.
