The operating temperature of the wire, what is the working temperature of the wire

There are many kinds of wires, check the "Electrician's Manual" The maximum allowable temperature of the bare wire is 70 degrees, and the maximum allowable temperature of the insulated wire is 65 degrees, see the figure below**:

The commonly used working temperature is generally divided into four grades, that is, as shown in the figure above: 25° 30° 35° 40 °, different working temperatures, their interception current is different, and the power carried is also different.

It is best to use a high-temperature wire with a specification of 200 degrees. It is available at the Industrial Appliance Store.

The cable material is divided into two parts: one is the conductor and the other is the insulator.

The function of a conductor is to turn on the current, so it generates heat, and the higher the current, the more it heats up (the heat is proportional to the square of the current). The insulator itself does not generate heat, but it is wrapped around the conductor, and the heat emitted by the conductor will be transferred to the insulator 100%, causing the temperature of the insulator to rise.

The conductor is made of metal, which is relatively not afraid of high temperatures, and one or two pairs of copper and aluminum will not have any effect. However, the insulator is made of organic matter, and it is relatively afraid of high temperatures, and the temperature of one or two will make the insulator unbearable.

Therefore, in order to ensure that the insulator of the cable will not be damaged by high temperatures, it is necessary to limit the heat generation of the conductor, that is, to limit the temperature of the conductor.

If we say that "the cable conductor can be allowed to operate at 90 degrees for a long time", it means that the working temperature of the cable conductor can be maintained at 90 degrees for a long time without causing additional damage to the insulating material of the cable.

But this 90 degrees is not absolute either. It is also permissible to exceed 90 degrees for a short period of time (not too much), and of course the life of the cable will be shortened a little bit as a result. Conversely, if the operating temperature is lower than 90 degrees for a long time, the service life of the cable will be extended accordingly.

The maximum allowable temperature is the maximum temperature that the cable can withstand without causing damage!

The maximum allowable operating temperature of the general wire is 65.

The ordinary wire insulation layer is generally made of polyethylene, polyvinyl chloride and other materials, and the allowable temperature of different insulation materials is different, such as PVC insulated wires, the maximum allowable temperature is 70 when the rated load is used; The maximum allowable temperature for a short time is 160 °C; XLPE insulated wire, the maximum allowable temperature at rated load is 90; The maximum permissible temperature for a short period of time is 250 °C, etc.

Factors influencing the temperature of the wire insulation:The allowable temperature of the wire insulation layer is related to the insulation material and the heat resistance level of the insulation material, the heat resistance level of the insulation material is divided into 7 grades, and the Y-level insulation material is generally natural textiles such as wood and fiber and plastics with low melting points.

Its ultimate operating temperature is 90 °C; Class E insulation materials are generally polyester film and Class A material composite, etc., and its ultimate working temperature is 120; Class B insulation materials are polyester enameled wire, polyester film, etc., and its ultimate working temperature is 130.

There are many kinds of wires, check the "Electrician's Manual" The maximum allowable temperature of the bare wire is 70 degrees, and the maximum allowable temperature of the insulated wire is 65 degrees, see the figure below**:

For example, ordinary wires can withstand high temperatures of 70 degrees Celsius, polyethylene wires can withstand high temperatures of 90 degrees, polyolefin wires can withstand high temperatures of 150 degrees Celsius, and silicone rubber wires can withstand high temperatures of 180 degrees Celsius.

High-temperature wire, refers to corrosion resistance, oil resistance, strong acid, strong alkali, strong oxidant, etc.; It has electrical insulation performance, high voltage resistance, low high-frequency loss, no moisture absorption, and large insulation resistance; It has excellent flame resistance, aging resistance and long service life.

Cable maintenance attention:1. The cable should not be damp, heated, corroded or bruised.

Second, the cable should be inspected for a certain number of years, and if any fault is found, it should be replaced in time.

3. Do not overload the cable.

4. Frequently check the use of electrical and wiring at home, and carry out maintenance and overhaul in a timely manner.

Fifth, for the line of the old building, found to be flooded or wet, especially the line in disrepair and aging, should immediately ask the electrician to repair.

6. For the lines that are easy to be soaked by floods, electricians should be asked to relocate the lines and take elevated and moisture-proof measures.

7. If there is a power outage in rainy days, the power supply should be cut off immediately, and an electrician should be asked to check the cause and send someone to take care of it.

The maximum allowable operating temperature of the general wire is 65.

The ordinary wire insulation layer is generally made of polyethylene, polyvinyl chloride and other materials, and the allowable temperature of different insulation materials is different, such as PVC insulated wires, the maximum allowable temperature is 70 when the rated load is used; The maximum allowable temperature for a short time is 160 °C; XLPE insulated wire, the maximum allowable temperature at rated load is 90; The maximum permissible temperature for a short period of time is 250 °C, etc.

Precautions for purchasing a power cord:

Look at the appearance of the power cord qualified products, its insulation layer is soft, tough, very elastic, the surface layer is tight, smooth, no roughness, and has a pure gloss. The surface of the insulation layer should have a clear and scratch-resistant mark, and the insulation layer feels transparent, brittle and non-tough.

According to the national standards, the wire surface should have a continuous mark of the manufacturer's name, product model and rated voltage. This is conducive to finding the manufacturer in time when problems occur during the use of wires, and consumers must pay attention to this when purchasing wires. At the same time, consumers should pay attention to the name of the manufacturer and product model indicated on the certificate when purchasing wires.

75 degrees Celsius.

The maximum operating temperature of a typical wire is 75 degrees Celsius, which includes the temperature rise generated by the operating current. Although the cable allows for this operating temperature, it will accelerate the aging of the wire insulation and shorten the life of the wire.

Rubber insulated wire, maximum operating temperature 65°, insulated PVC material, not more than 70°C.

A wire is a wire that transmits electrical energy. It is divided into bare wire, magnet wire and insulated wire. Bare wires have no insulation, including copper, aluminum flat wires, overhead stranded wires, and various profiles (such as profile wires, busbars, copper bars, aluminum bars, etc.).

It is mainly used for outdoor overhead and indoor busbars and switch boxes. Magnet wire is an insulated wire that generates a magnetic field when energized or induces an electric current in a magnetic field.

It is mainly used for motor and transformer coils and other related electromagnetic equipment. Its conductor is mainly copper wire, which should have a thin insulation layer and good electrical and mechanical properties, as well as heat, moisture, solvent resistance and other properties. Different properties can be obtained by using different insulating materials.

A wire is a wire that transmits electrical energy. It is divided into bare wire, magnet wire and insulated wire. Bare wires have no insulation, including copper, aluminum flat wires, overhead stranded wires, and various profiles (such as profile wires, busbars, copper bars, aluminum bars, etc.). It is mainly used for outdoor overhead and indoor busbars and switch boxes.

Magnet wire is an insulated wire that generates a magnetic field when energized or induces an electric current in a magnetic field. It is mainly used for motor and transformer coils and other related electromagnetic equipment. Its conductor is mainly copper wire, which should have a thin insulation layer and good electrical and mechanical properties, as well as heat, moisture, solvent resistance and other properties.

Different properties can be obtained by using different insulating materials.

Generally, the low-voltage power cable we use has a long-term allowable operating temperature of no more than +65 degrees.

Depending on the temperature rating of the wire, the temperature rating is generally determined by the type and formulation of the insulation and sheath material. Domestic home improvement wiring is generally 70 degrees Celsius.

For example, PVC has 60 degrees Celsius, and there are also 70 75 80 90 105 degrees Celsius.

There is also Teflon, which is 200 and 350.

Thermostat wax tablet methodDuring the test, a set of temperature indicator wax sheets are pasted with an insulating rod at the measured place or glued first in the event of a power failure. There are 60 types of wax tablets (yellow) (green (red)). The disadvantage of the thermometric wax tablet method is that the reaction time is long, the paste is inconvenient, and the temperature can only be roughly checked, so it is rarely used at present.

Color-changing thermometric brushworkIt is actually a disc used in the shipbuilding industry to monitor the heating working temperature during welding, and the temperature is indicated according to the discoloration characteristics of the color papping element in the pen at a certain temperature. To measure the contact temperature in the power cable line, a color-changing thermometer with a color-changing temperature of 70 base sheds can be used. When using, put the pen on the insulating rod and draw a line at the place to be measured.

When the temperature of the connector exceeds 70, the color of the pen line will change to lake blue. This method of measurement measures temperature quickly (1 2s), is easy to use, and is inexpensive.

Non-contact temperature measurement devices such as infrared thermometers can be used to measure controls. Now there is no use of thermal imaging.

Is there a telemetry device that shows the temperature distribution on the image? Some time ago, airports, stations, and docks all had this kind of body temperature screening equipment.

Abnormal. The copper core is allowed to use 4 amperes per square millimeter. The specification stipulates that the maximum allowable temperature rise of plastic (polyethylene) insulated cable is 40 degrees, and now many informal cable factories have cut corners on the cable, saying that it feels hot, and the cable does not know whether it is a copper core or an aluminum core, and the estimated temperature is above 60 degrees, there must be a problem.

If the wire is heated, it is normal, but if it is overheated, it will cause some safety problems, so the situation of overheating with the first code must be dealt with in time, and the cause must be found out before it can be better handled.

The cause of the heating of the wire.

1. The resistance does not match the specified requirements, and the wire is easy to heat up after running for a period of time.

2. Improper selection of wire model, generally the square number is small, the conductor cross-section is too small when using wires, the wire is overloaded, and long-term use is easy to lead to heat and heat dissipation imbalance.

3. The wiring is too dense, and the ventilation and heat dissipation effect is not good during operation, which is easy to lead to the occurrence of heating.

4. The nearby heat source is too close to the wire, which affects the heat dissipation of the wire.

5. The joint is not compressed, and the resistance through the joint is too large, causing the wire to heat up.

6. The insulation of the wire is poor, resulting in small insulation resistance.