Method and apparatus for switching of parallel capacitors in an HID bi-level dimming system using voltage suppression

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the transient voltage suppression means having a clamping voltage that is greater than peak voltage of the unswitched capacitor.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the transient voltage suppression means clamping voltage when combined voltage exceeds the clamping voltage of said means, thereby permitting control of clipping time and magnitude per cycle.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the electronic switch comprising zero-crossing opto-coupler devices.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the transient voltage suppression means comprising voltage suppressors in series.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the load comprising relatively high wattage HID lamping, the lamping comprising at least one lamp having a wattage of 1000 watts or greater.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the electronic switch comprising back-to-back 1200 volt SCR switching devices.

In a bi-level control system switched by means of capacitive switching and having an unswitched capacitor and a switched capacitor, an electronic switch for operation of relatively high wattage load, the improvement comprising transient voltage suppression means across the electronic switch for discharging residual charge from the switched capacitor when combined peak voltage exceeds clamping voltage of said transient voltage suppression means, the electronic switch comprising 600 volt zero-crossing opto-coupler devices.