increasing street lighting efficiency

8/9/2019 Increasing Street Lighting Efficiency

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Increasing Street lighting efficiencyEffect of line voltage increase on street lighting

By: Dr. Eng Mohamed H. Helal

Saving street lighting energy become simple and secure, a saving average of 25% to 60 % can be easy

achieved while keeping lighting task within standard limits!Some basic informations need to be reviewed

1) The total consumed power of a 250Watt High Pressure Sodium lamps circuit ( Lamp + Ballast is290Watt when the line voltage is 220Volt ( lamp voltage is 100 ~ 110V Lamp power is 250 Watt ballast

is 40 W )2) The total power consumed of same circuit will be 325Watt when line voltage is 230Volt ( lamp voltage

will be 115 ~ 120 Volt Lamp power = 283W, ballast 42 W)

3) The consumed power will reach 360Watt when line voltage is 240 Volt ( Lamp Voltage is 120 ~ 125 Voltwhile lamp power is 315 Watts and ballast 45 Watt )

4) Sodium Lamps are designed to work at 100Volt + 6% and 8 % when lamp voltage is increasedbecause of line voltage , lamp voltage will be increased too then lamp power will be up more thanpermitted limits effecting lamp lumen depreciation and service life become dramatically shorter ..

5) A case study using 250Watt HPS lamp with magnetic ballast at constant voltage 220Volt then run for 12hours , then next day increase the line voltage to 230 Volt and run for 12 hours third day increase the line

voltage to 240 Volt and run for 12 hours then compare was made , the reason for doing this study is todetermine the effect of line voltage increasing on street lighting and to calculate the relative consumption.

The electronic programmable ballast was programmed to work 2 hours at full power then 4 hours at 90%power then 4 hours at 75% power then go down to 65% power till the power is turned off .

The measured data was as following:

RED = Magnetic Ballast Green = Electronic Dimmable Ballast


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According to this program and at fixed voltage of 220V the electronic dimmable ballast will

save 24% from the billing energy for the customer while for the distribution company will

save 12 ~ 15 % more in form of Power factor improvement as electronic ballast is 99.9 %

compare to 90% for the magnetic and the Harmonics are reduced to 5% for the electronic

compare to 30% for the magnetic due to the use of capacitor that will distort the wave andincrease the harmonics .

Another great benefit is the starting current that will be down to 0.3 Ampere compare to 3,2

Ampere when using the magnetic ballast ..

When voltage is increased to 230 Volt the savings will be increased as well:

There is an average of 9% increasing in the magnetic circuit consumption when the line

voltage was increased by 10 Volts (4.5 % of the line voltage (220 Volt)According to standards line voltage can be increased by 10% (220 + 10% = 242 Volts )

When apply 240 Volts to magnetic ballast circuit the following data was obtained:


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The 250 Watt lamp circuit started to consume 360 Watts when line voltage is only 240 Volt , street lighting

voltage is usually much higher than these limits ( 245 ~ 255V at late night time )This phenomena will cause great damage as well as large energy consumption that is estimated to be 24%

from the circuit constant designed voltage ( 220 V )

290 Watt x 1.24 = 360

Conclusion:

Increasing of line voltage for a High Pressure Sodium Lamps that uses magnetic ballast willincrease the consumed power by and average of 1% for each increased 1 Volt from designed

Voltage .

Use of electronic constant power electronic ballast with AVR (Automatic Voltage Regulated)facility will save up to 39% from direct billing while will give other benefits that can bemeasured as 15 % more energy saving while increasing lamp service life and improving lamp

lumen depreciation and service life ..

For more informations contact Dr. Mohamed H. Helal .. [email protected]

increasing street lighting efficiency

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