Bi-Power Functionality In several countries an extra wire, a so-called control wire or switched line, is distributed throughout the street lighting network. When the street lighting is switched on, both the line and the switched line are energized to the 230V level. At a certain point during the night this switched line is switched off from the grid. The bi-power driver detects this signal as a command to reduce the output current to a lower preset value. In most cases this value equals 50%.

This procedure is already common practice for luminaires fitted with traditional discharge lamps For these sources however, the decrease in energy consumption generates limited savings. On the other hand, with LED equipped luminaires, the decrease in energy consumption is almost linear to the decrease in light output. The bi-power feature is a rather basic dimming method, lacking flexibility, but it generates considerable energy savings for night-time periods when less light is required.

Constant light Output (CLO) Constant Light Output (CLO) is a system to compensate for the depreciation of luminous flux and to avoid excess lighting at the beginning of the installation s service life. In fact, the luminous depreciation that takes place over time must be taken into account to ensure a predefined lighting level during the luminaire s useful life. Without a CLO feature, this simply means increasing the initial power upon installation in order to make up for luminous depreciation. By precisely controlling the luminous flux, one can control the energy needed to reach the required level - no more, and no less - throughout the luminaire s life.

LED lighting consumption with CLOLighting level required = LED lighting level solutions with CLO

Energy savings Excess lighting

LUX KWH

100,000 h 100,000 h

LUMINOUS FLUX

TIME

100 %

50 %

Control features

Standard lighting consumptionStandard LED lighting level

Energy savings

18