What is the formula for calculating the capacity of the engineering wire, and what is the formula fo

Estimation of the safe ampacity of various insulated conductors.

Formula 1: 2.5 down the whole nine times, up minus one straight number pair, three or five lines multiply 3.5, double and double groups halved times.

Note: "2.5 times the whole nine, up minus one straight pair," that is; That is, the following various aluminum core insulated wires have a safe current carrying capacity of from, from 4mm; Above, the relationship between the safe ampacity of the wire and the cross-section is: the wire number is arranged upward, and the multiple is gradually reduced by one; and 35mm; The safe ampacity of the wire is a multiple of the cross-section; That is, "three or five lines multiply three point five", 50mm; Above, the multiplier relationship between the number of cross-sections and the safety current is a group of two wire numbers, and the multiples are reduced in turn.

That is, "double and double in groups halved".

Special note: The table is suitable for aluminum wire insulated wires, and the ambient temperature is 25; c. Applying it openly. When the ambient temperature rises, the laying method changes, and when copper wire is used, it can be corrected by the following estimation method.

Formula 2: "Different conditions are treated separately, and high-temperature nine-fold copper is upgraded." Wire threading.

Two, three, four, eight, seven, six folds are the best to remember. ”

Note: When the wire used is a copper wire, its safe current carrying capacity is slightly larger than that of the aluminum wire of the same specification, which can be calculated by adding a wire number according to the table. If calculated as 16mm; of copper wire, which can be regarded as 25mm; The aluminum wire, with the formula one has 25 4 = 100a, that is, "high temperature nine-fold copper upgrade".

The number of wires threading through the pipe increases, and the safe current carrying capacity of the wires decreases. The estimate can be regarded as an open application, with a discount. The safe current when one tube passes through two wires is twice that of the open application.

The larger the wire diameter, the current carrying factor is lowered accordingly, and the coefficient is generally 4 A when it reaches 240 square millimeters, because the larger the wire diameter, the worse the heat dissipation is relatively square millimeter BV wire corresponding to the safe current carrying capacity of . If the wire is heat-resistant to 90 degrees. 105 degrees, or decoration special wire (nylon sheathed wire), fire-resistant wire, safe current carrying capacity increased to safety.

The safe ampacities of BVV wires are calculated according to 90% of the above current.

There is a current-carrying mantra that you can take.

The power of the wire = the safe current carrying capacity of the wire * 220V, although the wire is small in size, it plays an important role in the circuit, it carries the transmission of current, can effectively ensure the normal use of electricity, so we should not only choose a good quality wire, but also choose the right wire.

Relatively speaking, the thinner the wire, the less power it can carry in the electrical appliance; The thicker the wire, the more power it can carry. For example, induction cooktops.

The power is 1800 watts, the current is, it is recommended to choose a square copper core wire, if the power of the induction cooker reaches 4000 watts, it is recommended to choose a 4 square copper core wire. Ruler reputation.

Wire power considerations.

It is necessary to pay attention to how many kilowatts can be carried by 1 square wire, which should be determined according to the type of wire, for example, 1 square aluminum wire, its current bearing capacity is generally about 5A, that is, kilowatts, and the current that 1 square Tongling section line can withstand is larger, probably, that is, about kilowatts.

When arranging wires in home decoration, it is necessary to determine how many square wires need to be used, and you can judge by the current. Generally, the lighting voltage in the home is not too large, about kilowatts, so you can choose to use square wires. There are many electrical appliances in the home, such as refrigerators, air conditioners, washing machines, etc., these appliances usually have a large power, if calculated according to 5 kilowatts, the current is 23A.

So we're going to need about 4 square wires.

Number of squares8 = the number of currents, the power is 220 square number 8, this calculation method is enough margin, the current carrying capacity of the wire is related to many conditions, such as material, wire type, use conditions, connection, etc., so the maximum value is difficult to say exactly.

As long as it is a copper core wire, every square millimeter.

The cross-sectional area can safely pass through the rated current of 4--5A.

In a 220V single-phase circuit, the current is about about 1KW of power; In a 380V three-phase balanced circuit, the current is about 2A per 1kW of power.

The above values are very close to the results that can be calculated by physical calculation formulas, so electricians do not remember them in their work"Cumbersome"Just remember these formulas.

Every 1 square millimeter of copper core wire, if used in a 220V single-phase circuit, can safely carry the current passed by a load of 1kW; If it is used in a three-phase balanced load (e.g. electric motor) circuit, the current through the load can be safely carried through.

How many watts can a square wire load:

How many kilowatts of electricity is poured by the square wire, the load current value of the wire specified in the national standard, the square millimeter of the copper core wire is 16A 25A about 5500 watts.

Aluminum core wire square millimeter 13A 20A about 4400 watts 220VAC voltage for a long time not more than 10A is the most standard, most of the time does not exceed 15A is considered safe.

The formula for calculating power is: single-phase PUI power factor.

by the number of wires squared.

Correspondingly, the safe ampacities of wires are calculated.

Refer to the comparison table of the safe ampacities of the wires to see directly: the square number of wires The conditions of use of the wires (temperature, bushing) The safe ampacities of the wires.

The cross-sectional area of the wire commonly used in the home circuit is: 1 1 5 2 5 4 6 10 16 25 35. The above estimation formula is based on aluminum wire, and the copper wire calculation is automatically upgraded by one level.

For example: 4 covers are sold with aluminum wire 4 5 20a, but 4 copper wire 6 aluminum wire 6 5 30a. If the 4 copper wire is laid through the pipe, the safe current carrying capacity is 30 0 8 24a, and if the ambient temperature is 40 degrees, the safe current carrying capacity is 24 0 9 21 6a.

Estimating mantras

Multiply by nine at 2.5 and subtract one by one straight up.

Thirty-five times 3.5, double in a group minus five.

The conditions have been changed and converted, and the high-temperature nine-fold copper has been upgraded.

The number of pipe roots is two, three, four, eight, seven and six folds full of load current.

Note: The current carrying capacity (safety current) of various insulated wires (rubber and plastic insulated wires) is not directly indicated in this formula, but is expressed by "multiplying the cross-section by a certain multiple", which is obtained by mental arithmetic. As can be seen from Table 5 3, the multiplier decreases with the increase of the cross-section.

The above content refers to: Encyclopedia - Ampacity.

The formula for calculating line capacity is p=root number 3 (uicos). The transmission capacity of the transmission line (MVA) :p = root number 3 (UICOS).

The transmission capacity of the 35kV transmission line needs to be calculated according to the current and transmission power factor. Therefore, the formula for calculating the line capacity is p = root number 3 (uicos).