Cable television types and calculations

　　
　　1st, the definition and distinction of cables
　　The generalized wire and cable is additionally referred to simply because cable. The narrow sense cable comes from the insulated cable. It really is defined as an assembly of one or more insulated cores, and their particular respective possible coverings, overall protective layers and surface coverings. Cables can also have additional uninsulated conductors.

　　Chinese cable
　　China's wire and conductor products are divided to the following five categories based on their use:

　　1. Bare wire 2. Winding cable 3. Power cable SEVERAL. Communication cable and connection cable 5. Wire along with cable for electrical products

　　The basic structure involving wire and cable:
　　ONE. Conductors Conductor currents, wire and cable specifications are represented from the cross-section of the conductor

　　ONLY TWO. Insulation External insulation material reported by its withstand voltage amount
　　Second, the working recent and calculation
　　Electric (wire) cable connection operating current calculation formulation:
　　Simplex

　　I=P÷(U×cosΦ)
　　P-power (W); U-voltage (220V); cosΦ-power aspect (0. 8); I-phase recent (A)
　　Three phase
　　I=P÷(U×1. 732×cosΦ)
　　P-power (W); U-voltage (380V); cosΦ-power aspect (0. 8); I-phase latest (A)
　　The safe cut-off on the general copper wire is definitely 5-8A/mm2, and the safe cut-off in the aluminum wire is 3-5A/mm2.

　　In the single-phase 220V line, the present per 1KW power is all about 4-5A, and in a three-phase circuit when the three-phase load is balanced, the current per 1KW power is concerning 2A.

　　In other words, in a single-phase routine, each 1 mm A COUPLE OF of copper wire could withstand 1 KW of power load; three-phase sensible circuit can withstand communication cable 2-2. YOUR FIVE KW of power.

　　On the other hand, the higher the operating current belonging to the cable, the smaller this safe current per block millimeter.

　　The allowable safe operating current of the cable is:
　　Ten from five (less than ten times five)
　　One hundred and two (more than 100 times more than two)
　　2553 5 (two five times through four or three or perhaps five times three)
　　Two and also a half times 7905 (multiplied by means of 2. 5 points for any 70% and 95% lines)

　　That tube temperature is 80% (varies with temperature, the number connected with safe currents is increased by 0. 8 or even 0. 9)
　　Copper upgrade calculation (in the identical section of the aluminum core belonging to the basis of a rise, such as 2. 5 while in the copper core is a new 2. 5 in aluminum core rise, then according to four square mm aluminum core count)
　　Add half with the bare wire (half the initial safe current rating)
　　Third, the common electricity (line) conductor type

　　Cable specification unit meaning:
　　In the insert type, the letter B signifies the wire, the letter V suggests the polyvinyl chloride while in the plastic, and the letter R indicates the cord (the conductor is a variety of filaments twisted together). You don't have indication that the real estate agent core symbol or tough line (common single-core conductor) will be omitted.

　　Common cable forms:
　　BV-indicates a single birdwatcher core PVC insulated cable without sheathed wire. Pertinent to AC voltage 450/750V as well as below power devices, family appliances, instruments and telecommunications equipment wire and cable connection.