One day, one lady, with no knowledge of electrical engineering, revealed the reason for the lack of light in her apartment. There was a brief interruption, and the woman urgently wants him to live. You can laugh at this story, or better still look at its inappropriateness in the report. Electrical technicians, without any further information, know what kind of phenomenon it is and what it threatens to do if they open the short-circuit circuit. The information below is addressed to people who do not have technical knowledge, and who, like everyone else, are not insured against inconveniences associated with the operation of equipment, machines, equipment and emergency situations adjusted them. It is important for every person to know what short-circuits are, what their causes are, what their possible consequences are and how they can be avoided. This description cannot be completed without knowledge of the basics of electrical engineering science. A reader who does not know them may be bored and not finish reading the article to the end.
Popular introduction to Ohm's law
Regardless of the nature of the current of the electric lance, the fault lies only in the fact that there is a difference in potentials (or voltage, the same). The nature of this phenomenon can be explained from the example of a waterfall: since there is a difference between the rivers, the water flows directly from where it is, and if not, it will stand at home. Let the students know Ohm's law, which means that the force is greater than the voltage, and the force is less than the force of the inclusions:
I - the size of the struma, which is sometimes called the strength of the struma, although this is not a very literate translation from the German language. Measured in Amperes (A).
In fact, by force (that is, the reason for the acceleration) the strum itself does not exist, but it itself manifests itself during the hour of a short freeze. This term has already become common and is often used, although academics from some universities, having heard the word “power strum” from a student, immediately put it “unsatisfied.” “But how do we fire that we go out of the wiring under the hour of a short circuit? - Feeds the aggressive opponent, - What is not strength? The proof is due to respect. On the right is that there are no ideal conductors, and their thoughts are heated by this very fact. If we assume that R=0, then no heat would be seen, as is clear from the Joule-Lenz law, induced below.
U - the same difference in potentials is also called voltage. Survives at Voltakh (with us, beyond cordon V). It is also called electrodestroying force (EPS).
R - electrical support, so that the material will move through the flow path. For dielectrics (insulators) it is large, although not insignificant, for conductors it is small. Measured in Ohms, but evaluated as a pet value. Of course, whichever conductor is stronger, it is better to carry out the string, and whichever is more successful, the worse. Therefore, pets are measured in Ohms, multiplied by square millimeter and divided by meter. Whichever value the temperature increases, the greater the difference. For example, a gold wire conductor is 1 meter long and has a span of 1 sq. mm at 20 degrees Celsius, the lead value is 0.024 Ohm.
Another formula for Ohm's law for the full lancug, before it, the internal (power) support of the voltage source (ERS) was introduced.
Two simple, but important formulas
It is impossible to understand the reason why the current of short-circuiting occurs without mastering one more simple formula. The tightness, similar to the avant-garde, is old (without reactive storage units, more about them later) supplying a struma to the voltage.
P – tension, Watt or Volt-Ampere;
U – voltage, Volt;
I - Strum, Ampere.
The tension of the unstressed one is muted, but it is limited, therefore, due to its fixed value, the voltage changes due to the increased flow. The consistency of these two parameters of the working lance, expressed graphically, is called the current-voltage characteristic.
And one more formula is necessary in order to develop the structure of short-circuit currents, this is the Joule-Lenz law. Vaughn gives an indication of how much heat is seen under the hour, the support of the vanity, and even simpler. The conductor is heated with an intensity proportional to the magnitude of the voltage and the square of the flow. And, of course, the formula cannot be done without an hour, the longer the base is heated, the more heat will be seen.
What happens in the lancet when there is a short circuit
So, the reader can appreciate that having mastered all the physical laws in his head, he needs to understand the magnitude of the short circuit. Ale from the beginning the trace appears in the nutrition, scho, vlasne, tse taka. Short circuit (short circuit) - this is the situation if the pressure is close to zero. I admire the formula for Ohm's law. When considering this option for a lancet plot, it is important to realize that there is a great deal of inconsistency. In all cases, it will be surrounded by the support of the EPC engine. In any case, the short-circuit current is even greater, and according to the Joule-Lenz law, the larger it is, the more hot the conductor will be. Moreover, the storage rate is not straight, but quadratic, so that if I increases a hundredfold, then the heat will be ten times more. There are dangers in this place that need to be set to fire in an hour.
The wires fry until red (or even hotter), and they transfer this energy to the walls, floors and other objects that stick out and burn them. If the phase of the neutral conductor is adjusted, the source of a short circuit of the device, closed to itself, is to blame. The basic electrical wiring is the worst nightmare of fire inspectors and is the reason for the many fines that are imposed on unaccountable authorities. And the fault, obviously, is not the Joule-Lenz and Ohm laws, but the insulation that has dried out due to old age, careless or illiterate installation, damage to the mechanical nature or over-wiring.
However, the current of the short circuit, although great, is also not infinite. The amount of trouble that can be caused depends on the heating power and the parameters of the electrical circuits.
Lantsyugi of the zminnogo strum
The above situations were of a less veiled nature, but were in a state of calm. Most often, the power supply of both residential and industrial facilities vibrates as a result of an alternating voltage of 220 or 380 Volts. Problems with permanently insured wiring most often occur in cars.
There is a difference and difference between the two main types of electricity. On the right is that the passage of the exchangeable stream crosses the additional warehouse supports, called reactive and of the intellectual nature of the objects that arise from them. Inductances and capacitances react to a changing flow. The short-circuit circuit of the transformer is separated not only by an active (or ohmic, one that can be measured by an intestinal adjuster-tester) support, but by another inductive storage one. Another type of vantagement is emnisny. Schodo vector of active struma, vector of reactive warehouse diaphragm. The inductive stream rises, and the inductive stream advances it by 90 degrees.
The butt of the difference in the behavior of vantagement, which affects the reactive warehouse, may be the primary speaker. This is why fans of deep music re-vantage until the magnetic field does not knock the diffuser forward. The coil flies away from the core and immediately burns out, which is why the inductive storage voltage changes.
Vidi KZ
A short circuit circuit may occur in different lances connected to different terminals of a permanent or changeable circuit. The simplest thing on the right is the extreme plus, which is a rapport with the minus, without the need for vantage.
And as a result, there are more options. A single-phase short-circuit current occurs when the phase is connected to the neutral or grounded. In a three-phase circuit, incorrect contact between two phases may fail. A voltage of 380 or more (when transmitting energy to large lines via power lines) volts can also trigger unacceptable results, including arcing at the time of commutation. It is possible to close all three (or even at the same time with the neutral) switches at the same time, and the flow of a three-phase short circuit flows through them until the automation fails.
That's not all. Rotors and stators of electrical machines (motors and generators) and transformers often suffer from such an unpleasant phenomenon as interturn short circuit, when the power supply loops create their own ring. This closed circuit extends to the edge of a low support at the edge of the alternating stream. The short circuit force in the turns increases, causing the entire machine to heat up. Please, since things have gotten so bad, don’t wait until all the insulation melts and the electric motor starts up. The windings of the machine need to be rewound, for which special equipment is required. This is why there are quiet surges if there is a short circuit of the transformer through the “interturn” circuit. The less the insulation burns, the easier and cheaper it will be to rewind.
Rozrakhunok the size of the stream with a short circuit
No matter how catastrophic this other phenomenon may be, this assessment is important for engineering and applied science. The formula for short circuit current is very similar to Ohm’s law, it just requires some explanation. Otje:
I short circuit = Uph / (Zn + Zt),
I short circuit - The value of the short-term flow, A;
Uph - phase voltage, V;
Zn - rear (including reactive storage) support of the short-circuited loop;
Zt - total (including reactive storage) support of the life (power) transformer, Ohm.
The outer supports are designated as the hypotenuse of the rectum tricumus, the legs of which are the size of the active and reactive (inductive) support. It’s even simpler, you need to study the Pythagorean theorem.
More often than not, the formula for the short-circuit current is, in practice, experimentally derived curves. The stench is deposits of magnitude I k.z. Once the conductor is exhausted, the power transformer will be cut and tightened. The graphs are a collection of exponentially lower lines, and it is also impossible to select a subline. The method gives approximate results, and its accuracy fully satisfies the practical needs of energy engineers.
How the process works
It seems that everything is going smoothly. It started to go wild, the light dimmed and then went out. In fact, as a physical phenomenon, the process can be extended, intensified, analyzed and divided into phases. Until the emergency moment, the lancet is characterized by the flow rate, which is within the nominal mode. Unpredictably, the new support changes sharply to a value close to zero. Inductive storage (electric motors, chokes and transformers) are essential to facilitate the growth process. Thus, at the first microsecond (up to 0.01 s), the strength of the short-circuit voltage circuit becomes virtually unchanged and is further reduced during the beginning of the transition process. The EPC of this step gradually reaches a zero value, then passes through a new one and is installed at some stabilized value, which will ensure the passage of the great I short circuit. The flow itself at the moment of the transition process is a sum of periodic and aperiodic warehouses. The shape of the graph of the process is analyzed, from the result it is possible to determine the constant value of the hour, which is determined by the value of the delay, which is determined by the value of reactively ї (inductive) warehouse total support.
Impact strum short circuit
In technical literature, the term “short-circuit shock stream” is often used. Needless to say, it’s not that scary at all and there’s no direct relationship to electricity. The concept means the maximum value of I short. in the lancus of the changeable stream, which reaches its value begins in the period after the emergency situation has occurred. At a frequency of 50 Hz, the period is 0.2 seconds, for half - exactly 0.1 seconds. At this moment, the interaction of conductors, located close to each other, reaches the greatest intensity. The shock current of a short circuit is indicated by the formula, as in this article, the definitions are not for fakhivs and certainly not for students, without any sense. It is available from special literature and handbooks. In itself, this mathematical expression does not become particularly complex, but it will require a lot of voluminous comments that will immerse the reader in the theory of electric lances.
Corisne KZ
It would seem that it is an obvious fact for someone who, in short, is a very bad thing, unacceptable and undesirable. This can lead to a short-term breakdown of the object, disconnection of emergency equipment, and, in the worst case, to damaged wiring and further damage. So, all efforts must be concentrated on eliminating this adversity. However, the development of short circuit currents is a very real and practical alternative. A number of technical features have been found that can be used in the high flow rate mode. The butt can be a basic welding device, especially an arc one, which short-circuits the electrode from grounding during operation. The difference in power supply lies in the fact that these modes are of a short-hour nature, and the tightness of the transformer allows for vibration and re-vantation. When the electrode is welded to the point where it is finished, high currents pass through (the heat is measured at tens of amperes), which results in enough heat for local melting of the metal and creation of a metal seam.
Methodi zakhistu
In the early days of the rapid development of electrical technology, when mankind was still experimenting with galvanic devices, there were various types of generators, motors and lighting, the problem of the destruction of these devices due to conversion arose. zhen i strumi short zamykana. The simplest solution was based on the advanced installation of fusible elements, which reacted under the influx of resistive heat, as the flow exceeded the set value. Such servants serve people today, their main advantages lie in simplicity, reliability and cheapness. Ale є й shortcomings. The very simplicity of the “cork” (as the authorities of the fusible rates called it for their specific shape) provokes those who burn out, not to be clever, but to replace the elements that have gone wrong with first darts, violins, or even flowers. Can you guess that such a protection against short-circuit currents does not lose its noble function?
At industrial enterprises for the suppression of revantage of lancets, automatic vimikacs began to be used earlier, below the apartment panels, and for the rest of the decade, “traffic jams” were important to be replaced by them. “Automatic” is much simpler, you can not change them, but turn them on, having identified the cause of the short circuit and checking for it once the thermal elements have cooled down. Their contacts sometimes burn out, so it’s best to replace them and not be able to clean them for good. Larger folding differential machines with high voltage do not serve longer, but their functional significance is wider; they are connected to the voltage at the minimum turn of the flow “on the side”, for example, when affecting a person strum.
In everyday life, it is not recommended to experiment with short periods of time.
To ensure safety during the operation of household electrical appliances, it is necessary to correctly calculate the cross-section of the power cable and wiring. The fragments of the Milkovo assembly cut the wires of the building cable before installing the wiring through a short circuit. This threatens the guilt of the future. It is also important to choose a cable for connecting electric motors.
Rozrahunok struma
The size of the strum is determined by its tightness and is necessary at the stage of designing (planning) a living space - apartments, cabins.
- Deposit the value of the value select the life cable (wire), which connections and electrical connections can be made to the limit.
- Knowing the voltage of the electrical circuit and the external pressure of electrical devices, you can use the formula calculate the strength of the stream that needs to be passed through the conductor(Wire, cable). For its size, choose the area across the vein.
If you have electricity living in your apartment or cabin, you need to go through some complicated steps in order to properly install the electrical circuit.
Similar structures are designed for industrial purposes: determining the required area of cut of the cable cores for the time of connection of the industrial installation (various industrial electric motors and mechanisms).
Single-phase voltage 220 V
The power of the stream I (in amperes, A) is determined by the following formula:
I = P/U,
de P – external electrical supply (must be indicated in the technical passport of the device), W (vat);
U – voltage of the electrical circuit, (volts).
Below in the table is presented the magnitude of the requirements of typical household electrical appliances and the use of them with power (for a voltage of 220 V).
| Elektroprilad | Potency, W | Strum power, A |
| Pralna machine | 2000 – 2500 | 9,0 – 11,4 |
| Jacuzzi | 2000 – 2500 | 9,0 – 11,4 |
| Electrical subtexts | 800 – 1400 | 3,6 – 6,4 |
| Stationary electric stove | 4500 – 8500 | 20,5 – 38,6 |
| Microwave oven | 900 – 1300 | 4,1 – 5,9 |
| Dishwashing machine | 2000 - 2500 | 9,0 – 11,4 |
| Freezers, refrigerators | 140 - 300 | 0,6 – 1,4 |
| Electric meat grinder | 1100 - 1200 | 5,0 - 5,5 |
| Electric kettle | 1850 – 2000 | 8,4 – 9,0 |
| Electric coffee cooker | 6z0 - 1200 | 3,0 – 5,5 |
| Juicer | 240 - 360 | 1,1 – 1,6 |
| Toaster | 640 - 1100 | 2,9 - 5,0 |
| Mixer | 250 - 400 | 1,1 – 1,8 |
| Hairdryer | 400 - 1600 | 1,8 – 7,3 |
| Praska | 900 - 1700 | 4,1 – 7,7 |
| Gunpowder | 680 - 1400 | 3,1 – 6,4 |
| Fan | 250 - 400 | 1,0 – 1,8 |
| TB | 125 - 180 | 0,6 – 0,8 |
| Radio equipment | 70 - 100 | 0,3 – 0,5 |
| Adjust the lighting | 20 - 100 | 0,1 – 0,4 |
Presented to the little one electrical control diagram for an apartment with a single-phase connection up to a voltage of 220 V.
As you can see from the picture, there are a lot of different electrical energy connections through the auxiliary circuit breakers to the electrical machine and to the heating machine, which may require insurance for the installation of appliances that the apartment will have. A provider who brings down vitality is also responsible for satisfying the need for energy-supplying people.
Aim lower table for attached wiring for single-phase apartment connection diagrams for selecting a dart at a voltage of 220 V
| Peretin lived dart, mm 2 | Diameter of conductor core, mm | The Middle Ages lived | Aluminum lived | ||
| Strum, A | Potency, W | Strum, A | Pressure, kW | ||
| 0,50 | 0,80 | 6 | 1300 | ||
| 0,75 | 0,98 | 10 | 2200 | ||
| 1,00 | 1,13 | 14 | 3100 | ||
| 1,50 | 1,38 | 15 | 3300 | 10 | 2200 |
| 2,00 | 1,60 | 19 | 4200 | 14 | 3100 |
| 2,50 | 1,78 | 21 | 4600 | 16 | 3500 |
| 4,00 | 2,26 | 27 | 5900 | 21 | 4600 |
| 6,00 | 2,76 | 34 | 7500 | 26 | 5700 |
| 10,00 | 3,57 | 50 | 11000 | 38 | 8400 |
| 16,00 | 4,51 | 80 | 17600 | 55 | 12100 |
| 25,00 | 5,64 | 100 | 22000 | 65 | 14300 |
As can be seen from the table, the crossbars were deposited in the same manner as the material from which the wires were prepared.
Three-phase voltage 380 V
With a three-phase electrical current, the power of the current I (in amperes, A) is calculated using the following formula:
I = P /1.73 U,
de P-stress, W;
U - voltage in the boundary, V,
Since the voltage in a three-phase electrical circuit is 380 V, I can see the formula:
I = P/657.4.
Once a three-phase power supply with a voltage of 380 is connected to the unit, the connection diagram will look like the current order.
Peretin is alive in the life cable with varying voltage in a three-phase circuit with a voltage of 380 V for attached wiring is presented in the table.
| Peretin lived dart, mm 2 | Diameter of conductor core, mm | The Middle Ages lived | Aluminum lived | ||
| Strum, A | Potency, W | Strum, A | Pressure, kW | ||
| 0,50 | 0,80 | 6 | 2250 | ||
| 0,75 | 0,98 | 10 | 3800 | ||
| 1,00 | 1,13 | 14 | 5300 | ||
| 1,50 | 1,38 | 15 | 5700 | 10 | 3800 |
| 2,00 | 1,60 | 19 | 7200 | 14 | 5300 |
| 2,50 | 1,78 | 21 | 7900 | 16 | 6000 |
| 4,00 | 2,26 | 27 | 10000 | 21 | 7900 |
| 6,00 | 2,76 | 34 | 12000 | 26 | 9800 |
| 10,00 | 3,57 | 50 | 19000 | 38 | 14000 |
| 16,00 | 4,51 | 80 | 30000 | 55 | 20000 |
| 25,00 | 5,64 | 100 | 38000 | 65 | 24000 |
For the growth of the struma in the lantsugs there is a vitality, which is characterized by a great constant reactive pressure, which is characteristic of stagnant electrical power supply in the industry:
- electric motors;
- lighting fixtures;
- welding transformers;
- Induction furnaces
In case of swelling, it is necessary to undergo medical treatment. For tight fittings and installed parts of the reactive tension of the body, and therefore for such fittings, the tension coefficient is taken equal to 0.8.
Zmist:
The flow of charged particles in an electrical conductor is called an electrical flow. Electrostrum is not characterized only by the amount of electrical energy that passed through the conductor, since in 60 minutes an electrician equal to 1 Coulomb can pass through it, but the same amount of electric energy can be passed through a wire. Idnik in one second.
What is the strength of the struma?
If you see the amount of electricity that flows through the conductor at different intervals of an hour, it is clear that in a shorter period of time the current flows more intensely, then another value is introduced into the characteristics of the electric current - this is the strength of the current, which is characterized by the flow that flows into the conductor, per second to hour . By one unit, the magnitude of the force of the flow that passes through the electrical equipment is taken by the ampere.
In other words, the strength of the electric current in the conductor is the amount of electricity that has passed through its crossbar in a second per hour, marked with the letter I. The strength of the electric current is expressed in amperes - the same amount as the ancient forces of the constant current that pass via endless parallel wires with the smallest with a retina, remove one side by 100 cm and spread out in a vacuum, which interacts with each other per meter of the conductor with a force = 2*10±7 Newton steps per 100 cm of the conductor.
Fahivtsi often indicate the size of the strum to pass through; in Ukraine (struma strength) it is equal to 1 ampere, if 1 coulomb of electricity passes through the crossbar of the conductor every second.
In electrical engineering, you can often use other quantities at a given value of the power flow to pass through: 1 milliampere, which is a traditional unit / Ampere, 10 minus the third stage Ampere, one microampere - ten per minus w Ostogo stage Ampere.
Knowing the amount of electricity that passed through the conductor in a short period of time, you can calculate the power of the stream (as they say in Ukraine - the power of the stream) using the formula:
If the electric lance is closed and there is no anterior gallbladder, then the same amount of electricity flows through the skin area of its transverse cut per second. Theoretically, this is explained by the impossibility of accumulating electrical charges in any place of the Lanzug, so the force of the current through it is, however, the same.
This rule is true even in folding lances, if there is a collar, but also applies to the dozen sections of a folding lance, as can be seen in the appearance of a simple electric lance.
How the power of the strum is simulated
The magnitude of the force is measured by a device called an ammeter, and also for small values - a miliammeter and a microammeter, which can be seen in the photo below:
There is an idea among people that if the power of the stream in the conductor before the acquisition (living) is measured, then the value will be greater than after it. This is Milk's idea, based on the fact that there is no significant amount of effort expended on those to bring companions to life. Electrostrum in the conductor is an electromagnetic process, in which the charging of the electronics takes place, they directly collapse, and the energy is transmitted not by the electrons, but by the electromagnetic field from which the conductor emits.
The amount of electrons that came out of the cob of the lancet, the same number of electrons, and after living at the end of the lancet, the stink cannot be wasted.
What kind of conductors are there? The experts give the meaning of a “conductor” - this is a material in which the parts that carry a charge can move freely. Such power in practice can be used to destroy all metals, acid and salt. And the material or speech, in which the flow of charged particles of difficulty or the burning of the weak, is called insulators (dielectrics). The most advanced dielectric materials are quartz or ebonite, piece insulator.
Visnovok
In practice, the current supply operates with great values of power, up to hundreds, or even thousands of amperes, and also with small values. In everyday life, the value of the current in various settings can be an electric stove, which reaches a value of 5 A, and a simple frying lamp can reach a value of 0.4 A; for a photocell, the value of the current that passes is measured in microamps. The lines of municipal transport (trolleybus, tram) have a maximum current of 1000 A.
Electrical energy carries a high level of insecurity, since neither the workers of nearby substations nor everyday appliances are protected. Short-circuit current is one of the most unsafe types of electrical energy, but there are methods to control it, protect it and eliminate it.
What is it like?
A short-circuit shock (SCS) is a sharply growing shock electrical pulse. The main concern is that, according to the Joule-Lenz law, such energy has a very high level of heat. As a result of a short circuit, darts may melt or electrical components may burn out.
Photo – time diagramIt consists of two main warehouses - the aperiodic warehouse strum and the intermittent warehouse.
The formula is periodic
The formula is aperiodic As a matter of principle, it is easier to observe the very energy of aperiodic guilt, which is omniscient, pre-emergency. Even at the moment of the accident, the difference between the phases has the greatest amplitude. Also, his peculiarity does not mean the type of guilt of his strum in the margins. The lighting diagram will help show the principle of this flow.
The device, through high voltage during a short circuit, short-circuits at a small distance or “shortly” - so this phenomenon has lost its name. There is a stream of short three-phase fault, two-phase and single-phase - here the classification is based on the number of closed phases. In such surges, short circuits may result in short circuits between phases and to ground. Then, in order to mean it, you will need to firmly ground yourself.
Photo – result of short circuit It is also possible to divide the short circuit according to the type of electrical installation connection:
- from grounding;
- Without anything.
To explain this phenomenon, let’s take a look at the butt. For example, there is a specific connection between the line and connections to the local power line for additional soldering. With the correct circuit, the voltage in the local electrical circuits will be reduced. Based on this, for the purpose of determining the strength of the short-term signal, we can use Ohm’s formula:
R = 0; Ikz = Ɛ/r
Here r - opir KZ.
By substituting these values, you can determine the current short circuit at any point along the entire power transmission line. There is no need to check the short circuit multiplicity.
Ways to grow up
It is acceptable that a short circuit has already occurred in a three-phase circuit, for example, at a substation or on the windings of a transformer, so that short-circuit currents are identified:
Formula – strum of triphasic mixing Here U20 is the voltage of the transformer windings, and Z T is the main phase (as a short circuit). If the voltage in the boundaries is an important parameter, it is necessary to arrange the support.
Electrical skin, transformer, battery contact, electrical darts - provide their nominal support. In other words, every skin has its own Z. They are characterized by a combination of active and inductive supports. Also, there are odors, but the stench is not significant for the breakdown of high-strength streams. Therefore, many electricians use a simpler method for calculating these data: arithmetic arrangement of the support of a stationary strum on successively connected plots. When these characteristics are in mind, it is not important to follow the formula below to develop a new support for a plot or a whole border:
Formula for full grounding De ε is the value of the EPC, and r is the value of the support.
Doctors, who are about to re-vamp the operations back to zero, decided to take the following form:
I = ε/r = 12/10 -2
Therefore, the power during a short circuit of the battery is still 1200 Amperes.
Using this method, you can open the circuit breaker for an engine, generator and other installations. In addition, it will not be possible to determine the permissible parameters for the skin-surrounding electrical device. In addition, it should be noted that in case of asymmetrical locking of the vantage, there is a different sequence, for the appearance of which it is necessary to know cos and op. For the development of the structure, a special table GOST 27514-87 is used to indicate these parameters:
The concept of a one-second short circuit is also clear, here the formula for the force of the current during a short circuit is calculated with the help of a special coefficient:
Formula - coefficient KZ It is important that if the cable is cut, the short circuit may be difficult to pass through for wiring. The optimal duration is up to 5 seconds. Taken from Nebrat’s book “Rozrahunok KZ at the Merezhakh”:
| Retin, mm 2 | Trivality of short circuit, permissible for a specific type of dart | |||
| PVC insulation | Polyethylene | |||
| Lived in copper | Aluminum | Mid | Aluminum | |
| 1,5 | 0,17 | neither | 0,21 | neither |
| 2,5 | 0,3 | 0,18 | 0,34 | 0,2 |
| 4 | 0,4 | 0,3 | 0,54 | 0,36 |
| 6 | 0,7 | 0,4 | 0,8 | 0,5 |
| 10 | 1,1 | 0,7 | 1,37 | 0,9 |
| 16 | 1,8 | 1,1 | 2,16 | 1,4 |
| 25 | 2,8 | 1,8 | 3,46 | 2,2 |
| 35 | 3,9 | 2,5 | 4,8 | 3,09 |
| 50 | 5,2 | 3 | 6,5 | 4,18 |
| 70 | 7,5 | 5 | 9,4 | 6,12 |
| 95 | 10,5 | 6,9 | 13,03 | 8,48 |
| 120 | 13,2 | 8,7 | 16,4 | 10,7 |
| 150 | 16,3 | 10,6 | 20,3 | 13,2 |
| 185 | 20,4 | 13,4 | 25,4 | 16,5 |
| 240 | 26,8 | 17,5 | 33,3 | 21,7 |
This table will help you understand the severity of a short circuit in normal operation, the amperage on the busbars and different types of wires.
Since it takes a lot of time to obtain the data behind the formulas, special equipment is required. For example, the indicator Shch41160 is very popular among professional electricians - it vibrates the short-circuit current of phase-zero 380/220V. The digital device allows you to significantly increase the strength of the short circuit in commercial and industrial applications. Such a device can be purchased from special electrical stores. This technique is good if you need to accurately measure the length of the loop and the section of the lance.
The “Emergency Emergency” program is also used, as it can quickly determine the thermal effect of the short circuit, an indicator of the waste of power in the flow. The verification is carried out in automatic mode, all parameters are entered and all the data is itself processed. This is a paid project, the license costs close to thousands of carbovants.
Video: protecting the electrical circuit from a short circuit
Zakhist and vkazivki shodo vyboru obladnannya
Regardless of all the insecurity of this device, there is still a way to limit or minimize the risk of emergency situations. It is very easy to use an electrical device to eliminate short circuits, which can be a flow-exchange reactor, which significantly reduces the thermal effect of high electrical impulses. But this option is not suitable for everyday vikoristan.
Photo - diagram of the protection block in short circuit At home, it is often possible to keep track of the circuit breaker and relay protection. These are very sensitive to the flow of interchange (maximum and minimum flow limits), and when they are moved, life is switched on. The machine allows you to determine the permissible level of amperes, which helps to increase safety. The selection is carried out in the middle of possession with a high class of protection, as required. For example, for a 21 ampere circuit, it is recommended to install a 25 A circuit breaker.
Briefly mumble.
Short flashing (short) This mode of operation of the electric energy source is called when its clamps are closed by a conductor, the basis of which can be set equal to zero. A short circuit occurs when wires are connected to each other to connect a source of electrical energy to a source, the fragments of which can be considered to be an insignificant point and which can be taken equal to zero. Short circuits may occur if the wire insulation is damaged.
Possible short circuit circuits
Considering those that the internal support of the device r 0 is even less, and the support of the ammeter is almost as high as 0, the force of the stream in the lancus increases to even greater values.
Short circuit in emergency mode, because The great strum that comes with this can lead to inaccessibility, both the device itself and the accessories, devices and wires included in the lancet. Except for certain special types of generators, such as welding ones, short circuits. Do not make unsafe conditions a normal operating mode. It is worthwhile to avoid these episodes if it is important to remove as much as possible from the generator. The high internal support of the generator limits the strum, and it does not reach a value that is unsafe for the generator
Butt:
The Lancug has a 220V voltage and has a 109 Ohm support. Electrical support of wires is 1 Ohm. Find out the strength of the struma lancet in the operating mode and in the short-circuit mode.
Read also
Briefly mumble. Short circuits (short circuits) are called such a mode of operation of the electrical energy source, when the circuits are closed by a conductor, the basis of which can be set equal to zero. A short loop occurs when people connect with each other...