What dangerously faulty electric equipment?

At malfunctions of electric equipment the automatic machine has to work and deenergize the device.

Электрическая схема включения человека и электропотребителей в сеть при обрыве нулевого провода

Circuitry of inclusion of the person and electroconsumers in network at break of the zero wire: 1 – place of break of the zero wire; 2 – electroiron; 3 – TV; 4 – the electroconsumer with the zanulenny body; 5 – metal body of the electroconsumer; R3– ground resistance at the consumer distance; QF– automatic cut; XS1, XS2– plug adapters; XS3– the plug adapter with zanulenny contact; I h – the current proceeding through the person.

At the same time the arisen small ignition can be extinguished the fire extinguisher without special difficulties. But happens that it is sewn up in the electric unit for any reason is absent or does not work. Here there can also be the real fire. In most cases violation or non-compliance with simple rules of electrical safety becomes the reason of the fires. Knowing rules of electrical safety, it is possible to minimize probability of emergence of the fire.

Now let's look what occurs in electric devices and installations that is the beginning of the cause of the fire. First of all we will remember properties of electricity, namely what occurs when passing electric current in the conductor. From the course of physics it is known that substances consist of atoms and molecules which form among themselves communication in the form of the crystal grid and that the movement of electricity is the movement of the charged particles in the substance.

Опасность сетей однофазного тока

Danger of networks of the single-phase current: and - the scheme of touch to the wire of the isolated network; - the equivalent .skhema; in - the scheme of touch to the ungrounded wire of network with the grounded pole; - the scheme of touch to the wire of faulty network; д - the scheme of touch to the wire of network with the grounded average point; е - the scheme of touch to two wires of network.

And so to the electron which should pass into the conductor and fast to run all electric chain, and then to come back in the source, on the way it is necessary to face the set of atoms and molecules. At such collision the electron transfers the part of the energy which will heat substance, and in our case the wire. It is all about quantity of these electrons: the more we will pass current through the conductor, the more it will heat up. Each device has the admissible norm of heating which miscalculates at the development stage.

Taking into account it copper windings of electric motors and different coils, such as actuator or electromagnet, contain strictly certain quantity of rounds which directly influences current. Besides heating dissipates on all conductor and manages to be cooled, transmitting heat to the environment surrounding it (the wire which is in the wall transfers heat to this wall, and the engine winding - to the body of the cursor).

Thereby at rated values of the permissible current of installation heat up to the certain safe level and do not cause ignition. And here is how only in the device for any reasons the quantity of rounds of the winding is broken, current from rated value sharply jumps up. Excessive heating of all electrochain and its further ignition results.

Safety locks which problem at increase in admissible values of current to switch-off the equipment and to stop further heating are widely used to prevention of emergencies.

It should be added that, unlike burning of not electric character, the burning installations before operation of the automatic machine or manual shutdown of electricity feed-in are energized. Therefore, it becomes dangerous to extinguish them by means of water. For this purpose it is necessary to use carbon dioxide fire extinguishers or sand.

In conclusion we want to give advice: do not put the crossing point in protection devices or instead of the necessary safety lock the wire bug.

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