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Hi all. Constant current LED lighting is a new concept to me. Not that difficult to get the head around, but I cannot find an answer to the following question:
How do I determine the maximum length of a ELV LED lighting circuit powered by a constant current driver?
For a constant voltage ELV circuit, a 5% voltage drop is the limiting factor - straightforward enough. For constant current, the voltage will rise (within its limits) to maintain the steady current, so a voltage drop calculation cannot be made.
I thought maybe this could be calculated by taking any surplus power from the driver, and allowing this be lost on the cable. From that, a resistance could be calculated from which a cable length could be determined.
For example:
Driver: 350mA, 9W
Load: 6W
Therefore surplus available power = 3W.
R=V/I
V cannot be determined, so let's use V=P/I, giving:
R = P/I²
R = 3/.35² = 24.5 ohms, which can be converted to a length of conductor of a chosen cross section.
Please let me know what you think, am I barking up the very wrong tree?
How do I determine the maximum length of a ELV LED lighting circuit powered by a constant current driver?
For a constant voltage ELV circuit, a 5% voltage drop is the limiting factor - straightforward enough. For constant current, the voltage will rise (within its limits) to maintain the steady current, so a voltage drop calculation cannot be made.
I thought maybe this could be calculated by taking any surplus power from the driver, and allowing this be lost on the cable. From that, a resistance could be calculated from which a cable length could be determined.
For example:
Driver: 350mA, 9W
Load: 6W
Therefore surplus available power = 3W.
R=V/I
V cannot be determined, so let's use V=P/I, giving:
R = P/I²
R = 3/.35² = 24.5 ohms, which can be converted to a length of conductor of a chosen cross section.
Please let me know what you think, am I barking up the very wrong tree?