What effect does the heating cable wire shield have?
The shielding layer is a common component in the current heating cables and various types of cables, and a barrier is formed by the use of metal wire (mesh). In this period, xiao 'an will understand the important role of metal wire shield in heating cable with you:
The concept of shielding layer: generally speaking, when one end of the shielding layer makes an equipotential connection and the other end is suspended, it can only prevent electrostatic induction and cannot prevent the voltage induced by the change of magnetic field strength. In order to reduce the inductive voltage of the shielded conductor, a double layer shielding with insulation separation should be adopted when only one end of the shielding layer is equipotential connection, and the outer layer shielding should be equipotential connection at least two ends. In this case, the outer shield is connected with other equally potential problems to form a loop, which induces an electric current, thus producing a magnetic flux that reduces the strength of the source magnetic field, and thus basically cancels out the voltage induced when there is no outer shield.
Metal shielding layer is mainly to electromagnetic shielding, so that the internal electromagnetic interference is not external, and the internal electromagnetic energy does not easily run outside. In the electrical equipment in the use of more, all places or parts that need to resist electromagnetic interference need metal shielding layer. In the heating cable, the role of metal shield in the cable is mainly reflected in the following aspects:
The role of electric field in the insulation layer is strengthened to make electric field consistent with the direction of insulation radius (i.e. radial) and metal shield band grounded. The electric field is terminated on the metal belt, and there is no electric field outside the metal belt.
Prevent axial surface discharge. In the condition that the cable is not well grounded, because the semi-conductive layer has a certain resistivity, the potential distribution may be uneven in the axial direction of the cable, causing the cable to discharge along the surface.
The protection system of power station needs the outer conductor shielding. The wrapped copper belt has excellent lightning protection characteristics.
Normally flow through the capacitor current, the metal belt can be used as the circuit of short circuit fault current when short circuit.
Through the above understanding of the cable shielding layer technology, what xiao-an also wants to point out here is: the radiation problem of the heating cable electric ground heating, users who do not know the structure of the heating cable will definitely worry about the radiation problem of the cable, and may give up this high-quality heating method. So what we need to know is that the amount of radiation produced by the heating cable through the shielding layer process is no different from the amount of radiation produced by our home appliances (lighting bulbs). Do not go into the heat cable radiation big mistake.
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