Elements called fuses are most commonly used to avoid a short circuit that may occur and occur in any electrical system. Its operation necessarily takes place from the fusion of the fuse element, inserted in its interior. This fuse element is a conductor having a small cross section, when exposed because of its high resistance, to a higher heating than the other conductors when the current enters.
It impinges on a wire connected in parallel with the fusible element and that will slowly release a spring that will act on a type of plate or button, or even a screw, which is found coupled generally corporal cap. The fuses have within them, completely enclosing the element, a kind of granulated extinguishing material. Browning 2B5V74
The fuse element is essentially a blade or a wire, which may be of silver, tin, lead or alloy, nailed within a body, which is often porcelain, and must be sealed carefully . They need to contain an indicator, which can then be verified if the operation was actually performed.
Fuses are considered as the most used elements for protection against short circuits in electrical systems and their operation is based on the fusion of the fuse element, found inside. This element consists of a simple conductor of a small cross section, which in turn due to its high resistance passapor a higher heating than the other conductors in the passage of the current. reelcraft 82000OLS
The fuse element consists of a wire or blade, usually projected on materials such as tin, silver, lead or alloy, inserted into a closed porcelain body. It has an indicator, which has the function of allowing the verification whether it acted or not. It is a wire connected in parallel with the fuse element, which may release a kind of spring that acts on a platelet or screw, usually attached to the body cap.
The fuse can be found in different forms and depending on the nominal current of the fuse, it strikes one or more wires or blades in parallel with some sections of reduced section. In it, they may also contain a soldering point, in which the melting temperature will be much lower, compared to that of the element acting for long duration overloads.
The power contactors are for maximum currents up to approximately 600 A. In general, they have three main contacts of the NA type – normally open, for the operation of three-phase loads and can also be provided with coupled auxiliary contacts. An important factor to be verified in the use of the contactors is the sparks produced by the impact during the switching of the contacts, as this causes the natural wear of the contacts, besides constituting risks to human health. The intensity of the sparks can be aggravated in humid environments and also with the intensity of electric current circulating in the panel. In this way different forms of protection are applied, resulting in a classification of these elements. Basically there are four main categories of employment of contactors:
– AC1: it is applied in ohmic or little inductive loads, as heaters and furnaces the resistance;
– AC2: for drive of induction motors with winding rotor; air motor
– AC3: it is application of motors with cage rotor in normal loads like pumps, fans and compressors;
– AC4: is for heavy maneuvers, such as driving the induction motor under full load, reversing in full gear and intermittent operation.