Cable tv types and calculations

　　Earliest, the definition and distinction of cables

　　The generalized wire and cable is also referred to simply as cable. The narrow sense cable describes the insulated cable. It could be defined as an assembly of one or more insulated cores, and their particular fire-resistance cable respective possible coverings, complete protective layers and surface coverings. Cables can have additional uninsulated conductors.

　　China's wire and cable connection products are divided into your following five categories in line with their use:

　　1. Clean wire 2. Winding cable 3. Power cable SOME. Communication cable and connection cable 5. Wire as well as cable for electrical equipment

　　The basic structure involving wire and cable:

　　ONE. Conductors Conductor currents, wire and cable specifications are represented by cross-section of the conductor

　　A COUPLE OF. Insulation External insulation material reported by its withstand voltage amount

　　Second, the working present and calculation

　　Electric (wire) conductor operating current calculation formulation:

　　Simplex

　　I=P÷(U×cosΦ)

　　P-power (W); U-voltage (220V); cosΦ-power component (0. ; I-phase latest (A)

　　Three phase

　　I=P÷(U×1. 732×cosΦ)

　　P-power (W); U-voltage (380V); cosΦ-power thing (0. ; I-phase current (A)

　　The safe cut-off in the general copper wire can be 5-8A/mm2, and the safe cut-off in the aluminum wire is 3-5A/mm2.

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

　　In other thoughts, in a single-phase routine, each 1 mm A COUPLE OF of copper wire could withstand 1 KW regarding power load; three-phase nicely balanced circuit can withstand 2-2. SOME KW of power.

　　Nonetheless, the higher the operating current on the cable, the smaller this safe current per sq millimeter.

　　The allowable safe operating current on the cable is:

　　Ten away from five (less than twenty times five)

　　One hundred and two (more than BV cable 100 times more than two)

　　2553 5 (two five times by simply four or three or perhaps five times three)

　　Two plus a half times 7905 (multiplied by way of 2. 5 points to the 70% and 95% lines)

　　This tube temperature is 80% (varies using temperature, the number with safe currents is multiplied by 0. 8 or perhaps 0. 9)

　　Copper upgrade calculation (in exactly the same section of the aluminum core in the basis of a go up, such as 2. 5 inside the copper core is the 2. 5 in aluminum core rise, then according to four square mm aluminum core count)

　　Add half from the bare wire (half the main safe current rating)

　　3rd, the common electricity (line) conductor type

　　Cable specification type meaning:

　　In the wire type, the letter B shows the wire, the letter V indicates the polyvinyl chloride within the plastic, and the letter R indicates the cord (the conductor is a considerable number of filaments twisted together). There is absolutely no indication that the real estate agent core symbol or challenging line (common single-core conductor) is definitely omitted.

　　Common cable varieties:

　　BV-indicates a single office assistant core PVC insulated wire without sheathed wire. Relevant to AC voltage 450/750V along with below power devices, home appliances, instruments and telecoms equipment wire and cable.