What is the cross-sectional area of power cord for 380V 4KW three-phase motor?

A 380V 4KW three-phase motor requires a power cord of 1 square cross-sectional area.

The current is I = p/(1.732 ucosφ) = 4/(1.732 x 0.38 x 0.85) = 7.2a (according to the standard three-phase commercial power, cos φ is the load power factor, and general motors take 0.85).

Under the condition of low current, the safe current carrying capacity of aluminum cable per square is 9A, so the square number of aluminum wire is 7.2/9=0.8 square.

General cable specifications are (square millimeter): 1, 1.5, 2.5, 4,6, 10, 16, 25,35,50,70,95,125. So the aluminum wire should be 1 square.

The formula for calculating the safe current-carrying capacity of aluminum cables per square meter is: "2.5 times 9, minus a number from top to bottom", which refers to aluminum-core insulated conductors with various sections of 2.5 square meters or less, and its current-carrying capacity is about 9 times of the number of sections. Such as 2.5 square conductor, the current carrying capacity is 2.5×9=22.5(A). The multiple relationship between the current carrying capacity and the number of conductor sections with squares or more is that they are arranged upward along the number of lines, and the multiple decreases by L in turn, that is, 4×8, 6×7, 10×6, 16×5 and 25×4.

Extended data

1, performance

The power cord is only an accessory of household appliances, but it plays a vital role in the use of household appliances. If the power cord is broken, the whole appliance will not work. The household power cord shall be of BVV2×2.5 and BVV2× 1.5 models. BVV is a national standard code, which is a copper sheathed line. 2×2.5 and 2× 1.5 represent 2-core 2.5 mm2 and 2-core 1.5 mm2 respectively. Generally, 2×2.5 is used as the main line and trunk line, and 2× 1.5 is used as a single electrical branch line and switch line. BVV2 ×4 is used for single-phase air conditioning special line, and also provides special grounding wire.

Identification method

1, see the quality certificate of household appliances.

If the quality of household appliances is qualified, then the quality of the power cord of household appliances should also be tested, and there will be no big problem.

2, check the wire section

The cross section of the wire, the surface of the copper core or aluminum core of the qualified product should have metallic luster, and the copper with black surface or the aluminum with white surface indicates that it has been oxidized and is unqualified.

3. Look at the appearance of the power cord

The insulation (sheath) layer of qualified products is soft, tough and elastic, and the surface layer is dense, smooth, without roughness and pure luster. The surface of insulation (sheath) layer should have clear traces of friction resistance. For products made of informal insulation materials, the insulation layer feels transparent, fragile and inflexible.

4. Look at the core of the power cord

The wire core, which is made of pure copper raw materials and subjected to strict wire drawing, annealing and twisting, should have a bright, smooth surface, no burr, tight and flat twisting, soft and tough, and not easy to break.

5. Look at the length of the power cord.

Different electrical appliances have different requirements on the length of power cord, so it is best for decoration owners to know the length of qualified power cord before buying, so as to know fairly well when buying electrical appliances.

Baidu encyclopedia-power cord