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Switching Power Adapter Insulation Elements

Shenzhen GEO Technology Co.,Ltd | Updated: Aug 14, 2017

  Switching power adapter insulation elements

  Many friends may not be particularly aware of the switching power adapter insulation, but it does not matter, power adapter today to give you explain the insulation of the switching power adapter, we have to deepen the understanding of the power adapter, we take a look:

  First, the insulation type

  Safeguarding the circuit in normal tasks and the presence of circuit noise is higher than the risk of voltage, insulation and insulation must be taken. UL60950 Insulation is divided into five categories: functional insulation, basic insulation, additional insulation, double insulation and reinforced insulation.

  1, functional insulation: is equipped with accurate tasks necessary insulation, does not provide electric shock safety cover, but can increase the fire and extinguished. Such as enameled patent leather.

  2, the basic insulation: to avoid the most basic shock insulation. power adapter Insulation alone is not safe, but also through additional insulation and cover to the secondary shield to reach the safety requirements, such as coil insulation.

  3, additional insulation: independent insulation added to the base insulation, protection in the basic insulation occasionally effective, the supply of electric shock to the secondary cover. The minimum thickness of the additional insulation monolithic material must be greater than or equal to 0.4mm.

  4, double insulation: the combination of basic insulation and additional insulation, is a secondary insulation system.

  5, to strengthen the insulation: to avoid a large number of electric shock insulation system, equivalent to double insulation. The minimum thickness of the monolayer used in the inside is greater than or equal to 0.4 mm. Can have several layers, power adapter but each layer can not be tested alone.

  Second, the equipment level and insulation requirements

  Different types of circuits require different types of insulation:

  1, Class I equipment. This kind of equipment to take the cover to ground, that is, metal chassis access to the shelter, as a cover. In any dangerous voltage parts and chassis only between the basic insulation, such as the station communication power and so on.

  2, Ⅱ class equipment. Use double insulation and reinforced insulation without metal chassis and ground screws, such as portable chargers.

  3, Ⅲ class equipment. Powered by a SELV source and an external, potentially dangerous voltage, only base insulation, such as board power, power adapter is required. Figure 8.2.3 shows the block diagram of the external function block diagram, first from the block diagram of the external circuit function block is LCC, SELV, TNV, ELV or risk voltage, and then confirm the functional block between the external components and the use of insulation between the level and number. It can be seen from the figure that the risk voltage is at least bipolarly insulated from the user's accessible parts.

  For example, the floating ELV path must have a two-pole insulation, and there should be at least one level between the ELV and the user, otherwise the single-stage ELV circuit will be insecure. However, if the ELV circuit ground cover (supply level 1 cover), only one can be added. Similar conditions such as radiators and metal housings, must use the secondary insulation to isolate the user from the risk voltage. Unless the metal is grounded, can be used to level 1.

  Third, insulation materials

  According to the task voltage, electrical strength, temperature requirements, mechanical strength and task environment to determine the solid insulation materials, and these information should be anti-wet and flame retardant information; if the wire insulation material, but also requested data softness.

  The semiconductor devices and the remaining components are molded in solid insulation materials, and their insulation is evaluated and tested independently in the production process. Thickness is greater than or equal to 0.4mm; if there is two layers of insulation, there is no thickness request, but each layer must be satisfied with the electrical strength of the request; if it is, the thickness of the film, Three or more layers, and no minimum thickness request, but each two-layer combination must be satisfied with the corresponding electrical strength request. power adapter There is no thickness request for basic insulation or functional insulation.