Patent ID: 8058822

Claim:
A method for energy saving in public lighting systems, the method comprising: operating a sodium-vapor street light at a nominal power during a first predetermined number of hours T 1 ; reducing power supplied to the sodium-vapor street light to a first percentage of the nominal power, once a second predetermined number of hours T 2 has elapsed; reducing the power supplied to the sodium-vapor street light to a second percentage the nominal power, wherein the second percentage is smaller than the first percentage, once a third predetermined number of hours T 3 has elapsed; restoring the first percentage of the nominal power of the sodium-vapor street light, once a fourth predetermined number of hours T 4 has elapsed; restoring the nominal power of the sodium-vapor street light; and, concluding by automatically turning off the sodium-vapor street light after a fifth predetermined number of hours T 5 ; wherein ignition of the sodium-vapor street light involves regulation of frequencies around vacuum resonant frequency of a resonant tank circuit of a resonator, modulation of a switching frequency of the resonator prevents occurrence of an acoustic resonance phenomenon in the sodium-vapor street light and a sampling supply system of closed loop consumption to micro controller regulates output power to the sodium-vapor street light.