The protecting layer outside of 3.5.1 cable, should accord with the following requirements:
1 Exchange the electric cable of the single-phase return circuit, have through the non- magnetic metal bringing, steel wire armor.
2 In moist including chemistry, corroding environmenting or apt cabling that soaking water, the intersection of metal and set, strengthen layer, armour load onto should crowd and mould overcoats, thick the intersection of steel wire and armor of cable still should have fiber outside in the water.
3 Except that low temperature – under 20 ℃ environment or chemical liquid of pharmaceutial use soaks the place, and there is difficult firing of low toxicity the cable required should be used outside polyethylene while moulding overcoats while crowding, can adopt the polyvinyl chloride overcoat.
4 Using in has water or chemical liquid of pharmaceutial use to soak 6- 35KV importance or above 35KV of the place and hand in and unite polyethylene cable, should have metal plastics which accord with the instructions for use to compound and hinder aqueous layer, lead sheath, aluminium set or swelling type to hinder waterproof structures such as the hosepipe,etc..
Handing in in the ones that lay under water, under high pressure should also have structure of blocking water to unite polyethylene cable longitudinally.
3.5.2 Fill the oil cable
Bury and set up protecting layer choosing outside of the cable directly on 3.5.3, should accord with the following regulations:
1 When the cable bears relatively loud pressure or has machinery to damage dangerously, should strengthen layers or steel band armors.
2 Bring, might appear in the soil of displacement in the intersection of quicksand and layer, the intersection of backfill and land, the cable should have steel wire armors.
3 The termite endangers seriously and when the plastic cable does not have nylon overcoat, can adopt the metal set or steel band armor.
4 Except that this article 1 – 3 The situation outside one, can adopt and protect layer outside without the armor.
The fixed protecting layer choosing outside while laying the cable in the air of 3.5.4, should accord with the following regulations:
1 The oil immersion paper insulating lead sheath cable should have steel band armors when the arm type support is laid directly.
2 The small section insulating cable should have steel band armors when the arm type support is laid directly.
3 Bowing security such as the passenger traffic, commercial facility and expecting much and the mouse hurts the serious production placing, the plastics insulating cable can have metal set or steel band armors.
4 When high-drop that the cable lies needs the strength condition, can contain the steel wire armor.
5 Except that this article 1 – 4 Outside one, lay and support the intensive cable, does not include armors in ladder shelf or tray,etc..
6 Except that should according to the intersection of norm and 3.5.1 pairs of 3 this The regulation of one is adopted, and high-temperature over 60 ℃place should be adopted outside the cable of heat-resisting overcoats such as polyethylene,etc., should use the polyvinyl chloride overcoat.
7 It forbid use at passways closed fiber is outside tomorrow apply by cable.
Portable electric equipment,etc. needs to move or have cables that higher flexibility requires the return circuit curved frequently on 3.5.5, should adopt and protect layer outside the rubber.
The cable in the function place of radioactive rays of 3.5.6, should have suitable polyvinyl chloride, chlorine man’s rubber, sulphonating polyethylene of chlorine which tolerate the radioactive rays irradiation intensity,etc. to protect overcoats.
Lay the cable in protecting the tube on 3.5.7, should crowd and mould overcoats; The paper insulating lead sheath cable of the oil immersion, Shang Yi contains the steel armour floor.
Lay protecting layer choosing under water outside of the cable on 3.5.8, should accord with the following regulations:
1 Not open up to navigation in the brook etc. one storey of cables bearing pulling force of need armor, can select the steel band armor for use.
2 The cable in rivers, lakes, the steel wire armor pattern adopted should be met and received the strength condition. When having machinery that is damaged etc. to take precautions against to need to lay the condition, can select for use, accord with, protect, corrosion resistance strengthen to partial to layer outside the requirement.
Routes protect the choice of storey outside the cable while laying the condition through being different on 3.5.9, should accord with the following regulations:
1 The intersection of circuit and the total length exceed cable make length, should select for use, meet a full range of the same kind or difference of condition, try hard less the intersection of one and more than pattern.
2 When the circuit the total length exceeds the cable to make length, can adopt appropriate different patterns respectively according to the corresponding sector.


3.6 controls the metal shield deeply of the cable
Take electric current, voltage, direct current source that protect and trip, control return circuit,etc. need to strengthen two suits of systems of dependability while being double 3.6.1, should each adopt the control cable independently.
The return circuits of the following situations of 3.6.2, it is unsuitable to share the same control cable each other:
1 Weak electric signal, controlling return circuit and strong electric signal, controlling the return circuit.
2 Low level signal and high level signal return circuit.
3 Exchange the circuit breaker and divide a item of every weak electricity operated to control the return circuit.
The weak electric return circuit controls every pair of round wire of the electric return circuit of cable, should belong to the same control cable on 3.6.3.
The strong electric return circuit controls the cable, get rid of and lie in the supervoltage distribution device or run side by side with the high-pressure cable longer closely on 3.6.4, need to inhibit it outside the situation of the interference, does not include the metal shield.
, there should be metal shield.
Control the metal shield type choice of kind of the cable on 3.6.6, should influence according to the possible electric interference, charge to and inhibit the interference measure synthetically, meet the requirement for needing to reduce interference or overvoltage.
3.6.6.1 weak electricity lying in above 110KV distribution device controls the cable, should always have shielding, double-deck types are always shielded.
3.6.6.2 the intersection of computer and the intersection of monitoring system and signal control shielding of return circuit choose, should accord with following regulation:
1 Switch amount signal, can use and always shield.
2 High level analog signal, should spend the core of line to entangling to shield, can also spend the core of line to entangling to divide shielding if necessary.
3 Low level analog signal or quantity signal of the pulse, should use the core of line to entangling to divide shielding, can also spend the core of line to entangling to divide and shield compounding to always shield if necessary.
Other 3.6.6.3s situation,should according to electromagnetic induction, electrostatic induction and electric potential raising influence factor, adopt the suitable shielding pattern.
3.6.6.4 is while laying the way and requiring the cable to have steel armour, metal set, should fully utilize it to shield the function.
Need to reduce the control cable that the electricity interferes with on 3.6.7, can count and increase a spare core in the core of job outside.
Control connecting the place type of metal shield of the cable on 3.6.8, should accord with the following regulations:
1 The analog signal return circuit of the computer monitoring system controls the shielding layer of cable, can’t form two o’clock or multipoint earthing, should use the a little earthing centralized formula.
2 Except that 1 One,etc. needs a bit to ground the control cable shielding layer outside the situation, the interference in electromagnetic induction is relatively great, should
Two earthing adoption; Interference of electrostatic induction relatively old, can spend any ground.
It shield or it shield combinedly always,it is be internal to should be, outside if you can’t shield, if you can’t divide, use by some, earthing two o’clock.
3 Two earth choice, also should consider shielding layer unlikely to boil, melt under temporary the intersection of attitude and the intersection of electric current and function.

3.7 electric cables of sections
Basic demand that the cable core section of electric cable chose on 3.7.1.
The core temperature of cable under 3.7.1.1 largest job electric current function, can’t exceed the permission value confirmed according to the service life of cable. The working temperature of cable core of the lasting job return circuit, should accord with the regulations of appendix A.
The thermal effect produced in function time of electric current that 3.7.1.2 is maximum to short out, should meet heat stable condition. To return circuit that fuse box protect, meet heat stable condition can electric current apply, lower rigging the core temperature, less than the appendix A listed allowing value according to short out.
3.7.1.3 connects the voltage under the function of the electric current of largest job of return circuit to lower, can’t exceed the allowing value of this return circuit.
Large electric current return circuit or 35KV the above high-pressure cable of 3.7.1.4 relatively long distance, when according with the above-mentioned clause, should choose economic section, can until ” whether year expense expenditure minimum ” Principle.
3.7.1.5 aluminium core cable sections, it is unsuitable to be smaller than 4m㎡.
3.7.1.6 submerged cables are laid while needing the core of cable to bear pulling force and more rational, can select the section for use according to resisting and drawing the requirement.
Confirm and fill 10KV and the following daily cable while making the core section of minimum cable according to the electric current of lasting job on 3.7.2, should satisfied with the appendix B cable and fill and let and cut the flow continuously ‘ Suggestive basic value ,Influence, charge permission that correction coefficient confirm to, cut the flow according to following the intersection of service condition and difference by the intersection of appendix and C.
1 Ambient temperature difference.
2 The coefficient difference of thermal resistance of soil while laying is buried directly.
3 Many sticks of influence stood side by side cables.
4 The open air does not have sunshine shadow while sunshading to lay impracticably.
The intersection of norm and 3.7.2 this under the other situation that string stipulate, cable confirm, allow minimum the intersection of cable and core at the section according to lasting the intersection of job and electric current in 3.7.3, should calculate or test prove, calculate content or parameter, choose, should conform to the following regulations:
1 Intermediate frequency supplies power the return circuit uses the non- coaxial cable, it is not a worker that should charge to situation skin effect and neighbouring effect of next part increase the influence lossed and generated heat frequently.
2 Single the intersection of core and in order to cross, each other link when three sectors in unit system vary long high-pressure cable, should charge metal to, protect to loss, generate heat, influence while being additional layer.
3 Lay on plastics protecting cabling in the tube, should charge to the thermal resistance, influence; Arrange in the tube the cable in location of different holes should also be charged to the influence of heat factor each other separately.
4 Lay the cable in the refractory trough box of close, semi-closed or ventilative type, should charge to and include influence on increasing in thermal resistance of factor such as this type material, thickness of body of the box, size.
5 Exert fire-proof coating, band on in the cable when the thickness of cap rock is greater than 1.5mm, should charge to influence of its thermal resistance.
6 In the ditch when the cable pays attention to the sand and not has regular moisture content to supplement, should choose greater than ℃2.0 according to the sand quality situation? The coefficient of thermal resistance of m/W is charged to the influence increased to the thermal resistance of the cable.
The working temperature of core of the cable of 3.7.4 is greater than the cable of ℃70, calculate while allowing to cut the flow continuously, should still accord with the following regulations:
1 A fairly large number of this kind of cable is laid on the tunnel, shaft containing machinery ventilation, should charge to the influence that rise warm to the environment.
2 Electric current cut, lay in dry moist soil direct, under get rid of, implement, change soil, deal with, wait for, can avoid the situation of moving in moisture content, should the soil thermal resistance coefficient be below ℃2.0? m/W.
Confirm on 3.7.5 the cable allows to cut the ambient temperature of the flow continuously, should be according to using the average for many years of meteorological temperature of the area, and Wen Sheng who charge to real environment influences. Should accord with the regulations of table 3.7.5:
Cable allow ambient temperature to cut flow confirm continuously ‘ ℃ Table 3.7.5
The cable lays the place there is ambient temperature chosen in machinery ventilation
The ground temperature equally of hottest moon of the depths is buried in the land under the Central Committee
Supreme water temperature average of day of the hottest moon underwater
Average of maximum temperature of in the outdoor air, day of the hottest moon of cable trench
The factory building with the heat source apparatus ventilates the design temperature
The average of maximum temperature adds 5 ℃on day when does not there is not the hottest moon
Ventilate the design temperature in the general factory building, room
There is not the average of maximum temperature of day of the hottest moon
Does the average of maximum temperature add 5 ℃on day when the indoor cable trench does not is not there the hottest moon?
Tunnel
The tunnel ventilates the design temperature
Note: Act as? The intersection of norm and 3.7.4 pairs of 1 this Under the situation of one, can’t adopt and only add 5 ℃ directly.
The cable core section when the cable passes sector of different heat-dissipating conditions on 3.7.6 is chosen, should accord with the following regulations:
3.7.6.1 return circuit chiefs have not exceeded the situation made the length of the cable cable:
1 Important the intersection of return circuit and total length should relatively poor the intersection of sector and terms choose the same section according to dispel the heat among them.
2 When the submerged cable lays machinery intensity requirement to need to increase the section, the total length of return circuit can choose the same section.
3 Only if important return circuit, can press and choose the section to the heat-dissipating condition of sector of greater than 10m, but every return circuit should not exceed three kinds of specifications.
3.7.6.2 return circuit chiefs exceed the situation made the length of the cable, should choose the core section of corresponding appropriate cable according to the sector.
Protect the return circuit in holding the device absolutely on 3.7.7, confirm while allowing the minimum section of core of the cable according to heat stable condition of meeting shorting out, can calculate according to the regulation of the appendix D.
Should conform to the following regulations to choose to short out while calculating the condition on 3.7.8:
1 Calculate, use the intersection of system and wiring, should take the intersection of normal running and way, and should more than planning and development consider 5 year build up, according to project.
2 Short out some should choose electric current might take place through the intersection of cable and most large to short out return circuit.
3 Should short out and calculate according to three phases.
4 Short out for function time of electric current, should fetch and protect and excise time and circuit breaker to divide the sum of time of the floodgate completely. To straight feeders such as the motor,etc., should adopt and mainly protect time; Other situations, should press reservely and protect counting.
The power clicks three-phase Line four while grounding neutrally directly to make systematic cable neutral thread section under IKV on 3.7.9, can’t be smaller than working in the necessary minimum section continuously according to the largest uneven electric current of circuit; To having influence and return circuit of harmonic electric current, should meet the section of demand at the same time, and accord with the following regulations:
1 Put the electric light as the return circuit of main load with the gas, the section of neutral line is unsuitable to be smaller than the core line section of looks.
2 Except that 1 Outside a situation stipulated, the section of neutral line is not smaller than 50% of the looks core line sections.
3.7.10. order while grounding under IKV directly to if you can’t dispose, if you can’t protect by earth connection, lines or protection earthing line the cable core line sections of systems neutral neutral, choose to require.
3.7.10.1 neutral line, protect the intersection of earthing and neutral section of line, should accord with the intersection of norm and 3.7.9 regulation of the string this; Protect the earthing neutral line section, should still accord with the following regulations respectively according to the cable core material:
1 The core of copper, are not smaller than 10m㎡.
2 The core of aluminium, are not smaller than 16m㎡.
3.7.10.2 sections to protect ground wire, should respond to the request that the return circuit protected the reliable movements of the electric apparatus, and should accord with the regulations of table 3.7.10.
Allow the minimum section m㎡ according to the protection ground wire that heat stabilizes the requirement Table 3.7.10
The looks core line sectional S of cable protects the ground wire and allows the minimum section
S is less than or equal to 16S
16<S is less than or equal to 3516
S> 35S/2
Exchange, supply power, go back, route many sticks of cable make up in parallel, 3.7.11, should adopt the same section.
Effective section of the metal shielding layer of electric cable of 3.7.12, should warm to appreciate, exceed insulating partial to the short circuit of layer and permitting the average of maximum temperature outside under possible temporary the intersection of attitude and the intersection of electric current and function.