# Calculation of current carrying capacity of overhead cable

How to calculate the current carrying capacity of the power cable, such as 6 square millimeter aluminum core wire. The flow rate is 30A. The upper two of 100 means that the safe load flow of a wire of 100 square or larger is twice the diameter of the wire. For example, the safe load flow of a 150 square aluminum core insulated wire is 300A four 35 four three turns means 10 square The load flow of the 25 square aluminum core insulated wire is four times the diameter of the wire, and the wire is within 35 square to 70 square meters (not including three times). The two halves of 95 mean that the safe load flow of 70 square and 95 square inches of aluminum core insulated wires is twice the diameter of the wire. If it is not exposed, it will be folded according to the above method and then 20% (multiplied. If the ambient temperature exceeds 25 degrees, please calculate according to the above wire diameter method, and then discount it by 10%. When the temperature of the two pipes is When the conditions are used at the same time, Safety Luo calculates the ad flow rate as the diameter of the upper wire. The result is a 30% discount, and the bare wire plus half means the same cross section. The bare aluminum wire is 5 times the safe load of the insulated aluminum core wire flow The copper wire upgrade calculation means that the cross section of the copper wire is increased by one level in the order of the aluminum core wire section, and then according to the corresponding aluminum core wire conditions, for example: 35 square bare copper wire, upgrade according to the formula of 50 square aluminum core wire At the first level, calculate 50 * 3 * 5 = 225A, that is, 225A is 35 square safe load bare copper wire flow. For cables, there is no introduction in this formula. Usually directly buried grounded high-voltage cables can usually be directly calculated by the corresponding multiple in the first sentence. For example, the buried load of a 35 square millimeter high-voltage armored aluminum core cable is 35×3 = 105A. 95 square millimeters are about 95×5≈238A.
Usually, most units are estimated based on some simplified conditions and assumptions, and even some units simply apply various standards or standard conditions. The following load flow table. Since the actual installation conditions are very different from the standard conditions, the load flow obtained in this way is absolutely inaccurate.
The following common high-voltage cable models are: XLPE insulated power cable (ordinary high-voltage cable) 6 / 1KV6 / 6KV7 / .7 // 35KV product standard: Use characteristics: This product is suitable for power transmission and Distribution, can be used for fixed line installation, the maximum long-term working temperature of the cable conductor is 90 degrees, when a short circuit occurs (the longest time does not exceed 5S), the maximum temperature of the cable conductor does not exceed 250 degrees. Specifications: 35KV and below flame-retardant XLPE insulated power cables (flame-retardant high-voltage cables) 6/1KV6/6KV7/. 7 // 35KV product standard: Use characteristics: This product is suitable for power transmission and distribution with AC rated voltage of 35KV and below. The maximum long-term working temperature of the cable conductor is 90 degrees. When short-circuited (the longest time does not exceed 5S), the maximum temperature of the cable conductor does not exceed 250 degrees. Specification model: 35KV and below fire-resistant cross-linked polyethylene insulated power cable (fire-resistant high-voltage cable) 6 / 1KV6 / 6KV7 / .7 // 35KV product standard: use characteristics: this product is suitable for AC rated voltage 35KV power supply, transmission and distribution and In the following fixed installations, the maximum long-term working temperature of the cable conductor is 90 degrees, and the maximum temperature of the cable conductor does not exceed 250 degrees during a short circuit (the longest time does not exceed 5S).