How does High Pressure Sodium technology operate?
High pressure sodium (HPS) lamps have an efficacy of 80 to 140 lumens per watt, a long lamp life of 20,000 to 24,000 hours, and the best lumen maintenance of all HID sources. Wattages most commonly range from 70W to 1000W, with the 70W lamp using a 7uf-280Volt Capacitor and the 1000W using a 26uf-525Volt Capacitor, and the warm-up time is from 2 to 4 minutes. Re-strike time is approximately 1 minute.
The biggest drawback of high pressure sodium is the yellowish color light output, but it is acceptable for use in many industrial and outdoor applications (e.g., roadway lighting). High pressure sodium and metal halide lamps comprise the majority of HID lighting applications.