Phase Dimmers FAQ

What are the pros and cons of the various types of Dimming available in the lighting market?

  • Phase-Cut Dimming
      • The dimming curve of different fixtures may not match (i.e., the light output might not be changing uniformly for all fixture types even though they are commanded to the same dimming level).
      • Phase cut dimming cannot go to low light output levels.  Typically they will bottom out at 20~30% of max intensity
      • Phase cut dimming fixture may flicker at low output levels
      • Phase cut dimming fixtures (and the phase-cut controller) may have an audible hum/buzz at low output levels
  • 0-10V linear dimming
      • The light output level can go down to either 10% or 1% (depending on the driver selected)
      • There can still be differences in the dimming curve between different driver manufacturers.
      • The dimming control is analog and may have some inaccuracy.
      • A CU-4E will be needed
  • DALI/D4i digital dimming (2-wire protocol):
      • The light output level can go down to either 10% or 1% (depending on the driver selected)
      • The DALI standard defines the dimming curve; the drivers will be uniform in their dimming regardless of the manufacturer.
      • The dimming control is digital and, therefore precise.
      • No CU is required. However, if the driver is not SR/Dexal/D4i, a PSU will be required.

Explain the use of Phase dimmers and 3rd party devices?

Before you use phase dimmers, pre-determine whether the fixture supports forward or reverse phase dimming (also referred to as leading edge and trailing edge dimming), and choose a 3rd party device that is appropriate.

The EcoSense device supports only reverse phase dimming, while the Boca Flasher device supports forward phase dimming. Refer to the corresponding articles in the Support Portal.

Some fixtures use a screw-in Edison base LED lamp that supports both forward and reverse phase dimming. However, the designs are customized to use only one type of dimming for the best operation, including supporting the lowest possible dimming levels or flicker.  

The Phase-cut dimmer dims the fixture at line voltage based on a 0-10V signal from the Control Unit (CU).  Though the 3rd party dimmer may have a higher current rating, it is still limited to that of the CU since it is switching the load on and off. Refer to the Enlighted SU-5 and CU-4E with the EcoSense Line Dimming Control diagram.

What is the solution used for MLV (Magnetic Low Voltage) Dimming? 

Forward phase dimmers are used for MLV, reverse-phase for ELV, and third-party devices for line voltage (phase cut) dimming. Refer to Interfacing Enlighted Sensors with Triac and Phase-Cut Dimmable Fixtures using BOCA Flasher Smart Dimmer Control for more details. Please note that the devices used are expensive.

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