Whether performing under normal power or emergency power, the key factor required to operate LEDs in a fixture is supplying the correct DC voltage. The LED board (sometimes referred to as an LED array or also a ‘light engine’) needs a specific forward voltage in order to collapse the P/N junction of the diode, allowing current to flow through the LED which then emits photons that our eyes see as visible light. A fixture’s internal AC (or “normal”) driver is the key component that converts the incoming AC line power to the appropriate DC power for the LEDs during normal operation. This small detail is critical for fixture operation, but is generally not a factor of consideration to the installing contractor since compatibility between the driver and LED array has already been established by the manufacturer.
But what does the contractor do if they wish to install an emergency driver on the fixture?
Just like a normal driver, the emergency driver must deliver the proper DC voltage needed to illuminate the array. Forward Voltage data is typically not published, making it difficult to determine the needed operating voltage for the LEDs when selecting an emergency driver. Adding to this challenge is that, while LED boards may look and perform the same, the voltage requirements will vary depending on the series/parallel design of the individual LEDs. These factors add an unknown element to properly selecting an emergency driver.
To alleviate this problem, IOTA developed Auto-Sense forward voltage in ILB Constant Power emergency drivers. Most indoor ambient LED fixtures are classified as ‘Class 2’ luminaires, meaning they operate the LEDs at a voltage output no greater than 60 VDC while maintaining less than 100-watts of output power. IOTA Auto-Sense allows the emergency driver to detect the required voltage across the full Class 2 range (10-60VDC) and deliver the proper voltage needed to operate the LED array, whether it is 12V, 24V, 48V, etc. Some emergency driver manufacturers offer driver options for specific voltage ranges, such as 3V-20V or 12-39V, leaving it up to the contractor to figure out what is required. By offering Auto-Sense across the Class 2 voltage range, IOTA has removed the guess-work out of selecting the proper emergency driver when it comes to electrical compatibility.
Read the full Contractor Emergency Lighting Insider for more information, including IOTA solutions for non-Class 2 forward voltages. If you have additional questions, please feel free to contact IOTA at 1-800-866-4682!