Cut-off arrangement for and method of protecting a ballast-starter circuit from high pressure sodium lamp cycling malfunction

A method of protecting from damage a ballast-starter means of a luminaire of the type having a source of power normally connected to the ballast-starter means, and a high pressure sodium lamp across which the ballast-starter means supplies voltage of predetermined magnitude to thereby operate the lamp, in the event of a cycling malfunction wherein the lamp is extinguished and the ballast-starter means applies a voltage of magnitude greater than said predetermined magnitude across the extinguished lamp,

• the method comprising the steps of:
• (a) detecting the magnitude of the voltage across the extinguished lamp, and generating an electrical current signal when the magnitude of the voltage across the extinguished lamp reaches a threshhold magnitude which is greater than said predetermined magnitude;
• and
• (b) disabling the power source from the ballast-starter means in response to the generation of the electrical current signal to thereby protect the ballast-starter means from damage in the event of cycling malfunction.

In a luminaire of the type having a high pressure sodium lamp, a source of electrical power, and ballast-starter means normally connected to the power source and operative for supplying voltage of predetermined magnitude across the lamp to operate the latter,

• a cut-off arrangement for protecting the ballast-starter means from damage in the event that the voltage across the lamp exceeds said predetermined magnitude, comprising
• (a) sensor means for detecting the magnitude of the voltage across the lamp, and for generating an electrical current signal when the magnitude of the voltage across the lamp reaches a threshhold magnitude which is greater than said predetermined magnitude;
• and
• (b) means responsive to the generation of the electrical current signal for disabling the power source from the ballast-starter means to thereby protect the latter from damage.

A method of protecting from damage a ballast-starter means of a luminaire of the type having a source of power normally connected to the ballast-starter means, and a high pressure sodium lamp across which the ballast-starter means supplies voltage of predetermined magnitude to thereby operate the lamp, in the event that the voltage across the lamp exceeds said predetermined magnitude,

• the method comprising the steps of:
• (a) detecting the magnitude of the voltage across the lamp, and generating an electrical current signal when the magnitude of the voltage across the lamp reaches a threshhold magnitude which is greater than said predetermined magnitude;
• and
• (b) disabling the power source from the ballast-starter means in response to the generation of the electrical current signal to thereby protect the ballast-starter means from damage.