Why 24Vdc instead of 12Vdc?

21/12/22

The LED luminaire operating voltage, also defined as constant voltage with the Vdc abbreviation (Volts of direct current – continuous voltage), varies according to the type of LED and the design specifications. ┬áIt indicates the voltage applied to the LED circuit heads (i.e. the supply terminals), whether in cluster or linear circuit.

 

The correlation between the supply voltage (V-Volt) and the current (A-Ampere) necessarily forces the designer to make a careful evaluation of the operating voltage value in order to avoid current overloads and the consequent increase in appliance operating temperature.

Due to the practice associated with traditional light sources, in particular very low voltage halogen lamps, in the early years of LED luminaire development for the furnishings market, both the circuits and the relative power supplies were developed with an operating voltage value of 12Volt.

Sometimes, borrowing commercial lighting design choice, luminaires directly powered in constant current with operating values of 350mA (0.35A) or even 500mA (0.5A) and 700mA (0.7A) were supplied to the market. But these proposals were quickly dropped due to the complexity of power supply circuits (wired in series).

The wide availability of power supplies, the correct expectation of the market to unify the supply of lighting devices, and a sensational technical underestimation of some players, have made the development of luminaires with supply voltage @ 12Vdc very popular.

However, this choice has highlighted its limits, in particular with the development of linear luminaires and high linear density LED strips in which, with the same absorption, the choice of applying a supply voltage @ 24Vdc has allowed the operating current to be halved.

 

 

The real advantages of this choice are considerable, namely:

  • reduction of the PCB conductive track size, the consequent compacting of the light source dimensions and therefore of the luminaire;
  • reduction of power supply conductors and related connection systems (cables and connector);
  • extension of the linear source dimensions (lengths) thanks to the lower voltage drop;
  • greater availability of combination with external control and management systems of the device (sensors) thanks to doubling the maximum applicable load (eg 30W @ 12Vdc – 60W @ 24Vdc).

 

 

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