Bi-level lighting control system for hid lamps

A bi-level HID control system for connection to an HID lighting system having (i) an AC power supply branch circuit having a common line and a line voltage line and (ii) at least one HID luminaire, the luminaire including an HID lamp and ballast circuit connected thereto for controlling the operating current through the lamp, the ballast circuit having an inductance and a ballast capacitance connected in series with the lamp, a pair of power input leads each connected to a respective one of the common and line voltage lines of the branch circuit, and a pair of output leads, including one lead connected to the ballast capacitance, for connection to the lamp, said bi-level control system comprising:

• a) a control unit comprising
• i) an input for connection to the line voltage line,
• ii) an output, and
• iii) control means for switchably connecting said output to said input, and
• b) a slave unit for connection in the HID luminaire, said slave unit comprising
• i ) a slave capacitance, and
• ii) an electro-mechanical slave relay for switching said slave capacitance into and out of the ballast circuit in the luminaire, said slave relay including a moveable switch member moveable between first and second switch positions and a coil energizeable for moving said switch member,
• iii) a first lead connected to one side of said coil for connection to the common line of the branch circuit,
• iv) a second lead connected to the other side of said coil for connection to said output of said control unit, said second lead being connectable to said output with a single control line,
• v) a third lead connected to one side of said slave capacitance for connection to the one of the pair of ballast circuit output leads connected to the ballast capacitance,
• vi) a fourth lead connected to the other side of said slave capacitance for connection to the lamp in the luminaire,
• with said leads of said slave unit respectively connected to said output of said control unit, the common and line voltage lines of the branch circuit, and ballast, said coil of said slave relay is responsive to a line voltage signal received on said second lead from said output of said control unit to move said switch member for one of (a) switching said slave capacitance into the ballast circuit and (b) switching said slave capacitance out of the ballast circuit, whereby the light output level of the HID lamp is switched from a first light output level to a second, different light output level.

A slave unit of a bi-level control system for connection in an HID luminaire having (i) an HID lamp and (ii) a ballast circuit including a ballast capacitance connected to said lamp for controlling the lamp operating current, said slave unit comprising:

• i) a slave capacitance
• ii) and electro-mechanical slave relay for switching said slave capacitance into and out of the ballast circuit in the luminaire, said slave relay including a moveable switch member moveable between a normally closed and an open switch position and a coil energizeable for moving said switch member,
• iii) a first lead connected to one side of said coil for connection to a common, neutral line of an AC power supply branch circuit,
• iv) a second lead connected to the other side of said coil for connection to a switchable line voltage output of a control unit of the control system, said second lead being connectable to said output of the control unit with a single control line,
• v) a third lead connected to one side of said slave capacitance for connection to an output lead of the ballast circuit output connected to the ballast capacitance, and
• vi) a fourth lead connected to the other side of the slave capacitance for connection to the lamp in the luminaire,
• with said leads of said slave unit respectively connected to the switchable line voltage output of the control unit, the common and line voltage lines of the branch circuit, and the ballast, said slave relay is responsive to a line voltage signal received on said second lead from said output of said control unit for one of (a) switching said slave capacitance into the ballast circuit and (b) switching said slave capacitance out of the ballast circuit, whereby the light output level of the HID lamp is switched from a first light output level to a second, different light output level.

A control unit of a bi-level HID control system having a slave unit with a switched capacitor and a slave relay connected thereto, the slave relay being switchable with a line voltage signal received on a control input thereof, said control unit comprising:

• i) a pair of power inputs each connectable to a respective one of the common and line voltage lines of an AC power supply branch circuit;
• ii) a control output;
• iii) switching means comprised of an electro-mechanical control relay having first and second switch positions, in only one of said switch positions said control output being connected to said power input connectable to the line voltage line;
• and
• iii) switching control means for switching said control relay between said switch positions to control the connection of the line voltage line to the output, whereby switching of the slave relay is controlled when its control input is connected to said control output of said control unit with a single control line.

A bi-level HID lighting system including an AC power supply branch circuit having a line voltage line and a common line, at least one HID lamp, a ballast means connected to said HID lamp and said line voltage and common lines for providing stable operating power to said lamp, a switched slave capacitance, a slave relay for switching said slave capacitance into and out of circuit with said HID lamp and ballast means to switch said HID lamp between a first light output level and a second different light output level, said slave relay having a pair of control inputs, and a control unit connected to said slave relay for controlling the switching of said slave relay, wherein the improvement comprises:

• one of said control inputs of said slave relay is connected to said common line of said AC branch circuit;
• said control unit includes switch means for switchably connecting the line voltage line to an output of the control unit;
• and
• a single control line connects said output of said control unit to the other of said control inputs of said slave relay, whereby switching of said line voltage line to said output of said control unit switches said slave relay and one of a) connects the slave capacitance in circuit with said ballast and HID lamps and b) disconnects said slave capacitance from said ballast and HID lamp, whereby the light output level of the HID lamp is switched between the first and second, different output levels.