The choice of lighting distribution mode?

For landscape lighting and road lighting with short power supply distance and small calculation load, single-phase power distribution can be adopted, and the voltage drop and terminal short-circuit current value should be verified. Power Distribution The cabinet adopts outdoor type, and the bottom edge is 0.3 meters higher than the floor for floor installation.

For long power supply distance and large calculation load, three-phase power distribution is adopted, and three-phase A,B and C in low-voltage circuit are connected to each group of street lamps in turn to avoid three-phase imbalance. The power distribution cabinet adopts outdoor type, and the bottom edge is 0.3 meters higher than the floor.

Compared with the traditional single-phase circuit, the three-phase five-wire circuit used in the low-voltage lighting circuit can effectively reduce the line voltage loss.

7 street lamp cable protection pipe diameter size and laying requirements?

The total cross-sectional area of the conductors in the protective tube shall not exceed 40% of the cross-sectional area of the tube. The inner diameter of the tube should not be less than 1.5 times the outer diameter of the cable.

When the cable passes through the pipe and is buried at a depth of 0.5 meters in the green belt of the sidewalk, it passes through D50 steel pipe at the crossing place, and the earth covering depth is 0.7 meters. If the above requirements cannot be met, a layer of c20 reinforced concrete layer shall be added on the top of the pipe.

8 street lamp TT grounding system specific practices?

The local TT system without PE line is adopted, and the leakage protector with 300mA is added to the outgoing circuit breaker circuit.

All lamp poles and lamps must be firmly connected with the foundation reinforcement of the lamp pole. As the grounding device, the grounding resistance is less than 30Ω. After the construction of the lamp pole foundation, it must be tested whether the grounding resistance meets the requirements. If it fails to meet the requirements, the grounding level must be increased. For specific measures, see: 03D501-4 for grounding device installation in Atlas of National Building Design Standards.

9 street lamp design how to choose the transformer according to the calculation load?

The size of transformer capacity is not a problem, the key is the problem of power supply radius. In engineering, the power supply radius of street lamp box transformer is usually about 700 (if voltage drop calculation is necessary to be accurate). Therefore, one transformer is required for 1.5 kilometers, and three street lamp box transformers are recommended for 4.225 kilometers.

The capacity depends on the total power of the transformer-powered street lamps, plus 50% of the reservation (some main roads need advertising lighting or reserved intersection street lamps).

1) There is a leakage in your power calculation. NG250 of the lamp is the power of the high-pressure sodium light source. Don't forget the power of the ballast, which is generally 10-20% of the power of the light source. This is the estimated value. If there is the power value of the ballast in the lamp selection, add it directly.

2) You are more worried about the transformer capacity. Therefore, after the power (KW is the unit, active power) is added up, if it does not exceed 80 KW, the total number can be directly divided by 0.85 (that is, the power factor of street lamps), and the obtained number is assumed to be S1. Let S1 divide by the transformer capacity, and the requirement is met at 70-85%. Or divide S1 by 0.8 to look at the value and choose a transformer close to the standard capacity.

Of course, street lights should consider traffic signal electricity, advertising electricity, urban landscape electricity, transformer capacity is usually reserved at 70%, but must be combined with the owner whether to reserve these electricity.

If the transformer capacity is greater than 100KVA, it is necessary to consider the low-voltage compensation, the calculation method of the above method, but the power factor of the 0.85 is changed to 0.9 or 0.92.