Assuming that there are three sections of roads in a city with lengths of 3 kilometers, 5 kilometers, and 10 kilometers, and road lights are laid every 30 meters, with one on each side, the total number of street lights required for these three sections is 202 and 334 respectively. , 668 lamps, traditional street lamps with a power of 250W high-pressure sodium lamps as the standard, LED street lamps with a power of 50W as the standard for comparison.
The unit price of traditional street lights is 1,000 yuan/light, and the unit price of LED street lights is 3000/light. The cost of the light source for laying traditional street lights with three lengths of roads are: 202*1000=202,000 yuan, 334*1000=334,000 yuan, 668 *1000=668,000 yuan. The cost of the light source required to pave the road with three lengths of LED street lights are: 202*3000=606,000 yuan, 334*3000=1.002 million yuan, 668*3000=2.004 million yuan.
Let’s analyze the cost of laying cables for two light sources on a three-segment road. The load flow of the traditional street lamp trunk cable for a 3km road is I=P/U=202*250/220=230A, which requires a copper core with a cross-sectional area of 60mm2. The unit price of the cable is 120 yuan/meter, and the cable cost is 120*3000=360,000 yuan. The load flow of the LED street light trunk cable is l=P/U=202*50/220=44A, and it needs a cross-sectional area of 10mm2 The copper core cable requires a copper core cable with a cross-section of 12mm2, the unit price is 12 yuan/meter, the cable cost is 12*300=36,000 yuan, and the cable load flow of the traditional street lamp trunk line for 5 kilometers of road I=P/U=333 *250/220=377A, it needs a copper core cable with a cross-section of 90mm2, the unit price is 180 yuan/m, the cable cost is 980*5000=900,000 yuan, and the LED street light trunk cable load flow I=P/U=333 *50/220=73A, it needs a copper core cable with a cross-section of 20mm2, the unit price is 25 yuan/piece, the cost is 25*5000 = 125 thousand yuan, and the cable flow rate of the traditional street lamp trunk line for 10 kilometers of road I=P/U=666 *250/220=680A, it needs a copper core cable with a cross-section of 400m2, the unit price is 360 yuan/meter, the cable cost is 360*10000=3.6 million yuan, the LED street light trunk cable load flow I=P/U= 666 *50220=146A, it requires a 42mm2 copper core cable with a unit price of 60 yuan/meter and a cost of 600,000 yuan.
