Safety ampacity meter for YJV cables

It's good to buy this power cable operation regulations, and there are other cable knowledge regulations.

Insulated conductor ampacities estimation.

The relationship between the ampacity of the aluminum-core insulated wire and the multiples of the cross-section.

Conductor cross-section (mm 2) 1 1 5 2 5 4 6 10 16 25 35 50 70 95 120

The current carrying capacity is a cross section multiple 9 8 7 6 5 4 3 5 3 2 5

Current carrying capacity (a) 9 14 23 32 48 60 90 100 123 150 210 238 300

Estimation formula: 2.5 times 9, subtract one straight up and go. 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: (1) The current carrying capacity (safety current) of various insulated wires (rubber and plastic insulated wires) is not directly pointed out in this section, but is expressed by "multiplying the cross-section by a certain multiple", which is obtained through mental arithmetic. As can be seen from Table 5-3:

The multiplier decreases as the cross-section increases. "2.5 times nine, up minus one order" refers to 2 5mm' and below various cross-section aluminum core insulated wires, the current carrying capacity is about 9 times the number of cross-sections. For example, 2 5mm' wire, the current carrying capacity is 2 5 9 22 5 (a).

The relationship between the current carrying capacity and the number of cross-sections of the wire from 4mm' and above is to go up along the wire number, and the multiple is gradually reduced to L, that is, 4. "Thirty-five times three .five, double and double groups minus five", which means that the current carrying capacity of the wire of 35mm "is 3 5 times the number of cross-sections, that is, 35 3 5 122 5 (a). From 50mm' and above wires, the multiplier relationship between the current carrying capacity and the number of cross-sections becomes two two wire numbers in a group, and the multiples are subtracted by 0 5 in turn.

That is, the current carrying capacity of the mm' wire is 3 times the number of cross-sections, and the current carrying capacity of the mm" wire is 2 5 times the number of its cross-sectional area, and so on. The conditions have been changed and converted, and the high-temperature nine-fold copper has been upgraded.

The above formula is based on the aluminum core insulated wire and the open application at an ambient temperature of 25. If the aluminum core insulated wire is laid in an area where the ambient temperature is higher than 25 for a long time, the current carrying capacity of the wire can be calculated according to the above formula calculation method, and then it can be discounted; When using not aluminum wire but copper core insulated wire, its current carrying capacity is slightly larger than that of aluminum wire of the same specification, and the current carrying capacity of one wire number can be calculated according to the above formula method. For example, the current carrying capacity of 16mm' copper wire can be calculated as 25mm2 aluminum wire.

Legal analysis: the standard for the load current value of copper wire specified in the national standard:

The allowable long-term load current of 1 square copper core wire is: 6A -8A;

The allowable long-term load current of the square copper core wire is: 8A -15A;

The allowable long-term load current of the square copper core wire is: 16A -25A;

The allowable long-term load current of 4 square copper core wire is: 25A -32A;

The allowable long-term load current of 6 square copper core wire is: 32A -40A;

Before 2000, the circuit design was generally: 4-6 mm2 for the entrance line, mm2 for lighting, mm2 for sockets, and 4 mm2 for air conditioning. After 2000, circuit design is generally as follows:

The entrance line is 6-10 mm2, the lighting is mm2, the socket is 4 mm2, and the air conditioner is 6 mm2.

Legal basis: Article 11 of the Electric Power Law of the People's Republic of China The construction and renovation plan of the urban power grid shall be included in the overall urban plan. Urban people shall, in accordance with the plan, arrange land for substation facilities, transmission line corridors and cable passages.

No unit or individual shall illegally occupy the land for substation facilities, transmission line corridors and cable passages.

iec60502-2、ticw15。Cable-carrying genre stuffiness.

It refers to the amount of current passed by a cable line when transmitting electric energy, and the cable current carrying capacity when the cable conductor reaches the long-term allowable operating temperature under thermally stable conditions is called the long-term allowable current carrying capacity of the cable.

Copper wire load specified in the national standard.

Current value standard:

The allowable long-term load current of 1 square copper core wire is: 6A -8A;

The allowable long-term load current of the square copper core wire is: 8A -15A;

The allowable long-term negative slag attack current of the square copper core line dust beam bend is: 16A -25A.

The allowable long-term load current of 4 square copper core wire is: 25A -32A;

The allowable long-term load current of 6 square copper core wire is: 32A -40A;

Arabic numerals in the mantra.

The permutation with multiples is as follows:

For conductors with mm2, the number of cross-sectional areas can be multiplied by a factor of 5.

For conductors with mm2, the cross-sectional area can be multiplied by a factor of 4.

For conductors with mm2, the cross-sectional area can be multiplied by a factor of 3.

For a wire with mm2, its cross-sectional area can be multiplied by a multiplier.

For conductors with mm2, the cross-sectional area can be multiplied by a factor of two.

The above values are for aluminum wire, and the copper wire is calculated according to the larger level, for example: 10 square copper wire is calculated according to 16 square aluminum wire.

The safe ampacity of power cable YJV22-10KV-3*400: the ampacity of laying in the air is 565A, and the direct burial is 520A.

Internal factors affecting the current carrying capacity of the cable:

The properties of the wire itself are the internal factors that affect the current carrying capacity of the cable, and the current carrying capacity of the cable can be increased by increasing the core area, using high conductive materials, using insulating materials with good thermal conductivity with high temperature resistance, and reducing contact resistance.

Increase the core area to improve the current carrying capacity of the cable: the core area (cross-sectional area of the wire) is positively correlated with the current carrying capacity, usually the safe current carrying capacity of copper wire is 5 8A mm2, aluminum wire is 3 5A mm2.

The current carrying capacity comparison table of copper core cable is as follows:

<> cable current carrying capacity refers to the amount of current that a cable line passes through when transmitting electric energy, and under thermally stable conditions, when the cable conductor reaches the long-term allowable operating temperature, the cable current carrying capacity is called the long-term allowable current carrying capacity of the cable.

Calculate the safe ampacity of the wire, remember these 3 numbers, and it is better than you can do an electrician apprenticeship for 3 years.

The safe ampacity of YJV cable is that the amount of heat emitted by the YIV wire is just equal to the heat generated by the current through the wire, and the temperature of the wire no longer rises, and the current value at this time is the safe ampacity of the cable.

There are many factors that affect the current carrying capacity of YJV cable, mainly including these: ambient temperature, cable laying, altitude, etc.

In general, the higher the air temperature, the lower the current carrying capacity of the cable. The cable is laid in different ways, which has an effect on the temperature around the cable area, and thus its current carrying capacity. As the altitude increases, the current carrying capacity of the cable decreases, which also affects its service life.

Benefits of YJV Cables:

1. YJV cable has a longer service life in the long run, although it is still a little more expensive.

2. From the point of view of technical indicators, compared with the three-core YJV cable and the two-core VV cable, all parameters are higher. In the air of 40 degrees, 10 square meters of electricity Qi Qi dispatch cable, YJV cable current carrying capacity is 60A, VV cable current carrying capacity can only reach 46A. The maximum operating temperature is 90 degrees Celsius for YJV and 70 degrees for VV.

In the event of a short circuit, the maximum temperature is YJV250 degrees Celsius, and VV is what it looks like.

3. In terms of use effect, YJV is better. Because the YJV cable has better performance and is more resistant to aging. If the service life of YJV cable is 30 years, VV cable can only be used for 28 years.

4. Wider range of use. YJV cable is generally recommended for use in civil buildings because it is more environmentally friendly, safer, and does not produce toxic gases when burned.