Release time：2014.06.24 Browse the number：

A general principle, selection of wire and cable

When choosing wire and cable, generally pay attention to the wire and cable type, specification (conductor cross section).

The choice of ___________ cable models

When choosing wire and cable, want to consider to use, installation conditions and security; For example, according to different purposes, the optional power cables, overhead insulated cables, control cables, etc.; Depending on the installation conditions, can choose the general plastic insulated cables, steel tape armoured cable, steel wire armoured cable, anti-corrosion cable, etc.; According to the security requirement, can choose not secondary cable, flame-retardant cables, halogen-free flame retardant cable, fire-resistant cable, etc.

 

2. The choice of wire and cable specifications

 

Determine the use of wire and cable specifications (conductor cross section), the general should consider fever, voltage loss, economic current density, mechanical strength, etc. The selection criteria. According to experience, low voltage power line because of the load current is bigger, so the general choice under heating conditions section first, and then calculating the voltage loss and mechanical strength; Low-pressure ZhaoMingXian because of its higher requirements on voltage level, can according to the first selection section allows the voltage loss condition, then calculating the heating condition and mechanical strength; For high voltage line, according to economic current density first selection section, and then calculating the heating conditions and allow the voltage loss; And high voltage overhead line, should also check its mechanical strength. If the user does not have experience, should consult the opinions of the relevant professional units or persons. General selection of wire and cable specifications, see the table below:

 

Wire and cable specifications reference table

 

Conductor cross section

2 mm

Copper core PVC insulated cables

Ambient temperature of 25 ℃ overhead laying

IEC 227 01 (BV)

Copper core PVC insulated power cable

The directly buried installation environment temperature 25 ℃

VV22-0.6/1 (3 + 1)

Steel core aluminum stranded wire

Environmental temperature 30 ℃ aerial installation

LGJ

Allow the current carrying capacity A

KW capacity

Allow the current carrying capacity A

KW capacity

Allow the current carrying capacity A

KW capacity

1.0

17

10

 

 

 

 

1.5

21

12

 

 

 

 

2.5

28

16

 

 

 

 

4

37

21

38

21

 

 

6

48

27

47

27

 

 

10

65

36

65

36

 

 

16

91

59

84

47

97

54

25

120

67

110

61

124

69

35

147

82

130

75

150

84

50

187

105

155

89

195

109

70

, 230

129

195

109

242

135

95

282

158

230

125

295

165

120

324

181

260

143

335

187

150

371

208

300

161

393

220

185

423

237

335

187

450

252

240

 

 

390

220

540

302

300

 

 

435

243

630

352

Description: 1. The same specification aluminum conductor carrying capacity is about 0.7 times that of copper core selection of aluminum conductor is copper conductor is a specification, cross-linked polyethylene insulation can choose a small specifications, fire-resistant wire and cable, choose the larger size.

 

2) the calculation capacity is the three-phase 380 v, Cos phi = 0.85 as benchmark, if single-phase 220 v, Cos phi = 0.85, capacity should be by a third.

 

3. When the environment temperature is higher or the way of Ming fu, its safe carrying capacity would decline, at this time should be chosen large size; When used to frequent starting motor, should choose 2 ~ 3 specifications.

 

4) the PVC insulated wire according to single overhead laying methods of calculation, if wear pipe laying or root, should choose 2 ~ 3 specifications.

 

5 the above data are for reference only, the final design and determine the type and specification of the cable should consult relevant professional information or electrical manual.

 

Second, the use of wire and cable products use characteristics can be found in the specific product catalog.

 

Third, wire and cable of transportation and storage

 

___________ transportation dropped from a height are strictly prohibited in the cable or the cable with cable, especially in lower temperature (usually 5 ℃ or so and below), throw, fall cable would likely lead to insulation, sheath craze.

 

2. As far as possible avoid storage in the open air to bare cable, the cable is not allowed to lie flat.

 

3. Lifting package, it is forbidden to several plates at the same time. In vehicles, ships and other transportation, cable to use appropriate methods to be fixed, prevent collision or overturned, in order to prevent mechanical damage cable.

 

_____ the cable it is strictly prohibited contact with acid, alkali and mineral oil, with the corrosive substance for sequestration. Within the warehouse storage cable shall not have damaged the harmful gas of insulation and corrosion of metal.

 

⒌ cable during storage, should be periodically rolling (summer for 3 months time, other seasons can discretionary deferred). When rolling, we will send the under side of the house rolls up, lest floor be affected with damp be affected with damp rot. Store often should pay attention to the cable head are intact.

 

Pictures of cable storage period is limited to product delivery period, should not be commonly more than one and a half years, the longest do not exceed two years.

 

Four, wire and cable installation and construction

 

Wire and cable laying installation design and construction shall be in accordance with the GB 50217-94 "electric power cable design code" and other relevant provisions, and adopt the necessary cable accessories (terminal and connector). Operation quality, safety and reliability of power supply system is not only related to quality of wire and cable itself, also associated with the construction quality of cable accessories and wiring. Statistical analysis through the line fault, due to factors such as construction, installation and connection failure often than electric wire electric cable faults caused by ontology is much more likely. So to correctly choose wire and cable and related accessories, except in accordance with the requirements of specification for the design and construction, should also pay attention to the following issues:

 

___________ cable installation shall be carried out by a qualified professional unit or professionals, and do not conform to the requirements of the relevant rules of construction and installation, could lead to a cable system can not run normally.

 

This human, when laying cable should be unified command and control the rhythm, every one shoulder 1.5 ~ 3 m cable, put and pull, slowly.

 

3. Mechanical casting cable, generally adopts special cable laying machine is equipped with necessary drawing tools, traction, control proper size uniform, so as not to damage the cable.

 

_____ the cable before casting, to check the cable and head are intact appearance, pay attention to the direction of rotation of cable, when casting don't squashed or scratch the cable outer sheath, low temperature in winter when do not break way to straight cable, so as to avoid insulation, sheath craze.

 

⒌ when the bending radius of the cable laying should be greater than the specified value. After the cable laying before installation, measured with 1000 v megohmmeter cable insulation resistance between the conductor is normal, and according to the cable specifications, length and different as the result of the measurement of the ambient temperature properly modified, small specification (below 10 mm 2) solid core conductor cable should also measure the conductor is on and off.

 

Pictures of cable, such as directly buried must pay attention to the soil condition, general building under the embedding depth of cable should be no less than 0.3 meters, a soft or surrounding environment more complex, such as cultivated land, building construction site or road, must have certain embedding depth (0.7 ~ 1 m), in case of accidental damage from buried cable should be erected sign when necessary. (five wooden album)