Power-line Step-dimmable Lighting System
Publication Date: 2009-Nov-06
The IP.com Prior Art Database
Power Line Step-Dimmable Lighting System
The cost of the electricity energy production varies at different times of the day. And the cost reaches
its maximum during the peak load demand periods. As a major contributor to the load demand, lighting
loads need to be managed intelligently, by stepping down to lower light levels, during these peak load
hours. Again, during the off-business hours, there is a need to save energy by lowering the light level of
the system. Therefore, a multi-level lighting system, similar to bi-level step dimming is highly essential.
This will not only reduce the cost incurred by the customer, but also would significantly reduce the load
demand for the generating systems.
A major disadvantage of the conventional step-dim ballast is the presence of additional wire as
compared to the non-dimming standard ballasts. For light level reduction to actuate energy savings, the
whole system of ballasts needs to be re-wired. This makes it really difficult in retro-fitting, i.e. replacing
the standard ballasts with step-dimmable ballasts. FIG 1 shows the block diagram of the conventional
Secondly, the conventional step-dimming uses two separate switches S1 (to turn ON/OFF power), and
S2 (enable/disable step-dimming).
FIG 1: Block Diagram of the conventional three-wire step-dimming interface
The proposed novel design of the power-line step-dimming system solves these issues, by eliminating
the need additional wires, and provides a cheap solution for huge cost savings by light level reduction.
The power-line step-dimming system consists of a power-line step-dimmer switch, and a driver interface
for decoding the dimming signal from the power line. FIG 2 shows the block diagram of the proposed
The power-line step-dimmer switch consists of a three- position switch, and the step-dim signal injector.
The three-position switch can enable step-dimming signal injector to lower the light level, bypass the
signal injector to achieve full light output, or turn OFF the power.
STEP-DIMMER SWITCH BALLAST -1
Step-dim Signal Injection
FIG 2: Block diagram of the power-line step-dimming system
The step-dimmer switch when enabled, injects a signal of fixed time interval near the zero crossing of
the line current. FIG 3 shows the possible different type of signals injected at the zero crossing of the
line current. The signal injection at the zero crossing does not impact the THD of the line current.
The output of this step-dimmer can be used to power a number of step-dimmable electronic drivers; the
maximum possible number of the electronic driver depends on the total power drawn by the drivers.
The electronic driver interface circ...