POWERSAFE Magnetics now offers a bi-level ballast and control module system for the successful dimming of HID lamps.
Dimming circuits, regardless of type, force the lamp to operate at a current less than the nominal value. This results in lower than optimum arc tube temperature and some additives will not enter the arc stream, in turn causing reduced efficacy and a change in colour.
Operation at very low current, or starting at less than the full starting current will reduce lamp life, in some cases drastically. For these reasons, lamp manufacturers have, in the past, discouraged the use of dimming systems on HID lamps
Powersafe’s bi-level reactor ballast and control/starting module provides optimum operation of HPS and metal halide lamps at full power and acceptable operation at reduced power.
In the low power setting, the lamp will operate at 65% of nominal power (in watts) and lumen output will be approximately 52% of the full power value. This bi-level system provides all the necessary criteria for rated lamp life and performance and hence the manufacturer's warranty would normally apply.
If lamp’s starting were to actually occur in the reduced power mode, this could result in irreversible arc tube darkening, and lamp warranty may not apply. An example of how this could occur is where the system is operating in reduced power mode and a momentary supply voltage sag causes lamps to extinguish, but dimmer control does not reset. In this instance, with inferior systems, lamps will re-start in reduced power mode.
Using the Powersafe system, even if reduced level mode is selected when switched on, the lamp is always started at the full power setting, and allowed to warm up to full power before reduced level operation is possible.
The system will always provide a 12-15 minute delay between selection and actual switching to reduced power mode.
Additionally, the control module will not allow lamp ignition in the reduced power mode under any circumstances, even if the system is subjected to unusual events.