Six knowledge points for municipal streetlight design

- Jul 04, 2018 -

1. Is the main switch of the street light 3P or 4P?

If it is an outdoor light fixture, in order to avoid the danger of leakage, a leakage switch will be installed. In this case, a 4P switch is used. If the leakage is not considered, the main switch can be a 3P switch.

2. Advantages and disadvantages of different layouts of street lamps.

One-sided arrangement - for narrower roads, he requires that the installation height of the luminaire be equal to or greater than the effective width of the road. The advantage is that the inducibility is good and the cost is low. The disadvantage is that the road surface brightness (illuminance) on the side of the lamp is not lower than the side on which the lamp is set.

Staggered arrangement—requires that the installation height of the luminaire is not less than 0.7 times the effective width of the road. The disadvantage is that the longitudinal uniformity of the brightness is poor, and the inductivity is not as good as that of the one side. Symmetrical arrangement—requires that the installation height of the luminaire is not less than half the effective width of the road.


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3. Reasonable choice of street lamp installation height, cantilever length and elevation angle.

Installation height (h)—The economical installation height of the gas discharge lamp is 10-15 m. The glare of the installation is too low, the glare is increased, and the excessive glare is reduced, but the lighting utilization rate is lowered.

Cantilever length - should not exceed 1/4 of the installation height. The effect of too long cantilever:

1. Reduce the brightness (illuminance) of the sidewalk and curb on one side of the lamp.

2. The mechanical strength of the cantilever is required to be high, which affects the service life.

3. The effect is beautiful, resulting in an uncoordinated ratio between the cantilever and the pole. 4. The cost will increase.

Elevation angle—The elevation angle of the luminaire should not exceed 15 degrees.

The elevation angle of the fixture is to increase the range of illumination of the luminaire to the lateral direction of the road. Over-exposure caused increased glare, slower lanes and sidewalks reduced in brightness.

 

4. Reasonable power compensation for street lamps.

The single lamp dispersion compensation method is used to increase the power factor of various lamps to 0.9 or more, thereby reducing the capacity of the special lamp for street lamps by more than 51% and reducing the line loss by about 75%, which has obvious energy saving effect.


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5. Street light control.

Based on the principle of practical energy conservation, following the practice of most cities today, the control method combining light control and clock control is designed according to the different requirements of different traffic volume periods. That is, in the period of heavy traffic after dark, all street lights are lighted to ensure the safe passage of pedestrians and vehicles; after midnight, with the decrease of traffic volume, all street lights on one side are turned off by clock control to ensure normal traffic. Under the premise of achieving the most economical energy saving effect.

6. Lighting distribution method selection.

For landscape lighting and road lighting with short power supply distance and small calculation load, single-phase power distribution can be used, and voltage drop and terminal short-circuit current value should be verified. The power distribution cabinet is of outdoor type, and the bottom side is installed at a height of 0.3 meters above the floor.

For the long power supply distance, the calculation load is large, and the three-phase power distribution is adopted. In the low-voltage circuit, the three-phase A, B, and C phases are sequentially connected to each group of street lamps to avoid three-phase unbalance. The power distribution cabinet is of outdoor type, and the bottom side is installed at a height of 0.3 meters above the floor.

The lighting low-voltage line uses a three-phase five-wire loop to effectively reduce the line voltage loss compared to the traditional single-phase loop.


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