I. Relevant standards and specifications involving cable selection
1, DL / T5044-2004 People's Republic of China power industry standards
Selection of multi-core cable, the allowable current-carrying capacity can be calculated according to the value of single-core cable of the same cross-section.
The control line and signal line from the DC cabinet should be selected as copper core cable. Its voltage drop should not be greater than 5% of the nominal voltage of the DC system.
DC cable selection and laying should be consistent with the relevant provisions of GB50217.
2, GB50217 power engineering cable design specification
DC power supply circuit should be used two-core cable, when necessary, single-core cable can be used.
High temperature (100 ℃ or more) or low temperature (-20 ℃ or less) should not be used in PVC-insulated cables.
When laying cables directly buried, steel belt armored cables should be used when the cables are under great pressure or there is a danger of mechanical damage.
The temperature of the cable core under the action of the maximum working current shall not exceed the permissible value determined by the service life of the cable.
Determine the ambient temperature of the cable sustained permissible current-carrying capacity, if the cable is laid in the air or cable trench, should take the average of the highest temperature of the hottest month day.
3, the choice of cable path should be consistent with the following provisions
(1) to avoid the cable from mechanical external forces, overheating, corrosion and other hazards.
(2) to meet the safety requirements under the condition that the cable is shorter.
(3) easy to lay, maintenance.
(4) Avoid places that will be excavated and constructed
(5) cable in any laying method and all the path conditions of the up and down, left and right to change the components, should meet the cable allowable bending radius requirements.
Second, photovoltaic power generation system cable types, characteristics and laying methods photovoltaic power generation system cable types are mainly:
Specialized photovoltaic cable Power cable Control cable Communication cable RF cable
Specialized photovoltaic cable: PV1-F1*4mm2
String to the convergence box cable is generally used: PV special cable PV1-F1 * 4mm2.
Characteristics: photovoltaic cable, simple structure, its use of polyolefin insulation materials with excellent heat resistance, cold resistance, oil resistance, ultraviolet resistance, can be used in harsh environmental conditions, with a certain degree of mechanical strength.
Laying: It can be protected by wearing a tube, and utilizes the component bracket as a channel for cable laying and fixing to reduce the influence of environmental factors.
Power cable: ZRC-YJV22
Steel belt armored flame retardant cross-linked cable ZRC-YJV22 is widely used in: convergence box to DC cabinet, DC cabinet to inverter, inverter to transformer, transformer to the distribution unit of the connecting cable, the distribution unit to the power grid connecting cable.
The more common ZRC-YJV22 cable nominal cross section in photovoltaic power generation system are: 2.5mm2, 4mm2, 6mm2, 10mm2, 16mm2, 25mm2, 35mm2, 50mm2, 70mm2, 95mm2, 120mm2, 150mm2, 185mm2, 240mm2, 300mm2.
Features:
(1) Harder texture, temperature resistance class 90 ℃, easy to use, with small dielectric loss, chemical corrosion resistance and laying is not limited by the fall.
(2) High mechanical strength, good resistance to environmental stress, good thermal aging properties and electrical properties.
Laying: can be directly buried, suitable for fixed laying, to adapt to the needs of different laying environments (underground, water, trench pipe and tunnel).
Power cable: NH-VV
NH-VV copper core PVC insulated PVC sheathed fire-resistant power cable. Suitable for rated voltage 0.6/1KV.
Use characteristics: long-term allowable working temperature of 80 ℃. Allowable bending radius when laying: single-core cable not less than 20 times the outer diameter of the cable, multi-core cable not less than 12 times the outer diameter of the cable. The cable does not need to be pre-heated under the condition that the ambient temperature is not lower than 0 degree Celsius when laying. Voltage laying is not limited by drop.
Laying: Suitable for occasions with fire-resistant requirements, can be laid indoors, tunnels and trench pipe. Note that can not withstand the role of mechanical forces, can be laid directly in the ground.
Control cable: ZRC-KVVP
ZRC-KVVP copper core PVC insulated PVC sheathed braided shielded control cable. Suitable for AC rated voltage 450/750V and below control, monitoring circuits and protection lines.
Characteristics: Long-term permissible operating temperature is 70℃. Minimum bending radius radius is not less than 6 times the outer diameter.
Laying: generally laid in indoor, cable trench, pipeline and other requirements of shielding, flame retardant fixed place.
Communication cable: DJYVRP2-22
DJYVRP2-22 polyethylene insulation PVC sheath copper wire braided shield armored computer special flexible cable, suitable for rated voltage 500V and below for anti-interference requirements of electronic computers and automation connection cable.
Features: D