In H.P.S.V. lamps, the full form of H.P.S.V. is __________.

High Pressure Sodium Vapour (H.P.S.V.)

• H.P.S.V. lamps are a type of gas-discharge lamp that uses sodium in an excited state to produce light.
• It is highly efficient and has a long lifespan, making it popular for industrial lighting and outdoor security areas like parking lots and roadways.
• This tube contains xenon gas, sodium-mercury amalgam, and electrodes at both ends, all enclosed in a heat-resistant outer glass bulb.
• High-pressure sodium lamps have an efficiency of around more than 100 lumens per Watt, when measured for photopic lighting conditions.
•  Its efficiency increases with an increase in power rating. Some of the higher- power lamps (e.g. 600 Watt) have efficacies of about 150 lumens per watt or more.
• Normally these lamps are manufactured over wide range of ratings. The normal operating temperatures of these lamps are 300° C
• The average value life of the sodium vapour lamp is 3000 hr and these are not affected by voltage variations.