But if this does happen, the fuse (car on-board networks are mainly equipped with them) will die, like a samurai in battle - it will burn out, protecting the electrical circuit entrusted to it. It is not for nothing that in English there is a term sacrificial fuse for this type of detail - “sacrificial fuse”. The advantage of fusible disposable fuses is obvious. Firstly, when destroyed, they break the chain for sure. And secondly, they do it quickly, preventing overheating of the wires, and, as a result, a fire.
WHAT FUSES PROTECT FROM
As you probably already understood, the task of the fuse is to open the circuit in a critical situation, that is, one when there is a risk of heating the wires, melting them and catching fire, which is very dangerous, since the car is saturated with flammable liquids and materials. The situations are:
short circuit;
increasing the current in the circuit by a value higher than the fuse rating;
connection of a consumer whose power exceeds the calculated one for a given section of the network.
The latter especially applies to the cigarette lighter circuit and similar vehicle on-board sockets (located in trunks, glove compartments). After all, according to Ohm's law, in order to power the device, the power (and hence the resistance) of which is large, at a fixed voltage, you need to increase the current strength. And the wires may not be designed for this - they do not have the desired cross section, respectively, they will start to heat up. This can also be noticed in normal mode, by touching, for example, after work, the plug of a particularly productive compressor for tires or a car vacuum cleaner.
But as long as the current strength does not exceed that for which the fuse is designed, the situation is under its control, and is limited to a slight heating of the insulation, without proceeding to its melting. As soon as the current strength passes the critical level (including due to the fact that the resistance of the heated consumer increases), the thin metal conductor, the fuse core, burns out.
HISTORY AND VARIETIES OF FUSES
It is believed that the fuse was invented by Louis Francois Clement Breguet, a French electrical engineer ... and watchmaker - the grandson of the same Abraham-Louis Breguet, who founded the Breguet company. In general, the family gave the world many inventors: the grandson of the electrical engineer himself, Louis Charles, at the beginning of the 20th century, will create the world's first all-metal aircraft. In the meantime, in 1847, Louis Francois Clement, in the course of a series of experiments, found out that inserts made of wire of a certain thickness can burn out when the current in the circuit increases by an amount proportional to the cross section.
Actually, for a long time, automobile “sacrificial fuses” were not so sacrificial, because they were a plate with spring contacts, between which a wire 1-2 cm long was stretched ... and another 15-20 centimeters were wound higher, on a special small reel. When such a fuse burned out, the driver simply unwound a new piece of wire, installed it between the contacts, and it was possible to go further.
This continued until the 60s and 70s of the last century. Then, glass fusible inserts (or ceramic ones similar in size) with wire inside came into the automotive industry, familiar to many from household equipment, but were not widely used due to their fragility. Currently, they are installed only on additional circuits - more often for musical equipment or alarms, and are also present in car accessories.
The next rather lengthy stage (until the end of the 90s) is cylindrical fuses (“torpedoes”). We often called them ceramic, because of the material used to make the cylinder, although plastic inserts were also common - for example, foreign-made ones. They looked like small finger-type batteries, and they were also inserted into the sockets in much the same way. The contacts were located at the ends of the cylinder, they were connected by a fusible insert. It was from cylindrical fuses that the tradition began to mark fuses with color according to the face value.
Today, blade fuses (Blade type fuses, they are also pin or flag) are the most widespread. They are a U-shaped part, inside the translucent plastic case of which there is a fusible element, and two contacts protrude outward, inserted into the socket. Knife fuses are mounted and dismantled using plastic tweezers that come with the car or a spare set.
The color hierarchy of fusible links has finally been fixed, thanks to which the fuse rating can now be accurately determined even by people with poor eyesight.
In the modern standard, the colors are fixed in the following order:
black - 1A;
gray - 2A;
purple - 3A;
brown-yellow (sand) - 5A;
brown - 7.5A;
red - 10A;
blue - 15A;
yellow - 20A;
white - 25A;
green - 30A;
orange - 40A;
blue - 60A.
The application will protect
Firs of a higher denomination in modern cars, as a rule, are rare, and small denominations (less than 5 amperes) are quite rare. 10, 15, 20 and 30 amp fuses usually prevail in replacement kits entering the distribution network, protecting the most vulnerable electrical circuits.
When buying spare fuses, you must also pay attention to the size used in a particular car model (usually it is the same for all blocks, but there are exceptions, especially if the car has been upgraded or tuned).
There are several standards for knife type fuse links:
Micro2 /APT /ATR, dimensions 9.1 × 3.8 × 15.3 mm, ratings from 5 to 30A;
Micro3 /ATL, dimensions 14.4 x 4.2 x 18.1 mm, ratings from 5 to 15 A;
Mini / ATM / APM, dimensions 10.9 × 3.6 × 16.3 mm, rating from 2 to 30 A;
Regular / ATC / ATO / APR / ATS, dimensions 19.1 × 5.1 × 18.5 mm, rating from 0.5 to 40 A;
Maxi/APX, the largest fuses in size (29.2 × 8.5 × 34.3 mm) and rating (from 20 to 120 amps).
In addition to knife fuses, tape fuses are sometimes used - two terminals connected by a thin tape, often enclosed in a housing. These fuses usually have a large rating, so they are installed as a common fuse either in the box above the positive terminal or in close proximity to the battery.
To protect power devices that consume high currents (as a rule, also in engine compartment units), cartridge-type fuses (FJ12), consisting of contacts made of special alloys placed in a dielectric shell (cartridge), have been increasingly used lately.
WHAT THE FUSES PROTECT
Automotive fuses. Kinds. Check and replacement
In modern cars, there are no electrical circuits that are not protected by fuses. Usually they are placed in two blocks: under the hood, located at the top of the engine compartment, and saloon - usually located next to the driver's workplace at the bottom of the dashboard.
Consider the distribution of fuse links using the example of one popular crossover. There are two blocks here, the first is located in the engine compartment next to the computer, the second is under the steering wheel, closed with a coin box. In the engine compartment there are fuses for more powerful circuits: engine cooling fans (2 x 30A), electric motors of the stability control system (50A) and ABS (30A), heaters for the rear and front windows (20A each), both headlights separately, direction indicators (15A each). ), generator (10A), crankshaft sensor (30A) and several other important circuits.
In the cabin unit, there are mainly fuses with a nominal value of 10-15 A (circuits for dimensions, cigarette lighter, mirror control, heater and air conditioning fans, etc.), except for the wiper (30A) and brake lights (20A). To get to the fuses, the coin box must be dismantled without using tools.
HOW TO CHANGE THE FUSES. RECOMMENDATIONS
To locate a blown fuse, refer to your vehicle manual or the diagram on the fuse box cover.
Some fuses are equipped with fault indicator lights.
If the fuse is responsible for two devices (for example, washer and glass cleaner), note if both of them do not work. If one is not broken - apparently, the problem is not in the fusible link.
Do not remove the knife fuses with your hands, screwdrivers, a knife, use standard tweezers.
Install fuses strictly in accordance with the rating (in extreme cases, you can use a smaller rating, but not more).
In extreme cases, replace the fuse with a serviceable one from an unimportant circuit: seat heating, rear PTF, etc., but also strictly with a face value.
Do not make "bugs", "goats" from wire or foil, do not insert a bolt or coin instead of a fuse - this can lead to a fire. It's better to drive without a burning headlight than in a flaming car!