Digital Systems

Technical application guide

Planning, installation and operation

System planning
The planning of an LED system (e.g. an LED-based luminaire) must take into consideration the following important factors:

  • The selection of suitable LED modules.
  • The selection of suitable OPTOTRONIC (OT) LED drivers that cover all the requested functions (e.g. DALI) and parameters (e.g. SELV).
  • The selection of suitable sensors and LMS components.
  • The proper wiring of the OT LED drivers and the LED modules and their integration into a luminaire.

LED module selection
The very first step in planning an application is the selection of the appropriate LED module(s).
OSRAM LED modules can be divided into four categories

  • Constant-voltage (CV) modules
  • Constant-current (CC) modules with 1-to-1 arrangement of OT and LED module (each LED module has its own OT)
  • Constant-current (CC) module arrangements that consist of more than one LED module (more than one LED module connected to the same OT)
  • AC LED modules

LED driver selection

  • System wattage and forward current in CC systems
  • SELV or non-isolated drivers for linear and area CC systems

The examples below illustrate the difference in building up a system in SELV or non-isolated operation. Both examples use PrevaLED Linear Slim 2 modules as light source with the following nominal parameters.

Example A: 5-ft SELV luminaire

Example A: Parallel connection
Requirements: 5-ft luminaire in SELV mode, one row of LED modules, luminous flux of the LED system of 5 500 lm, CCT of 4 000 K, luminaire has to be dimmable via DALI.

Example B: 5-ft non-isolated luminaire

Example B: Series connection
Requirements: 5-ft luminaire in non-isolated (non-SELV) mode, one row of LED modules, luminous flux of the LED system of 5 500 lm, CCT of 4 000 K, luminaire has to be dimmable via DALI. Exactly the same conditions as in example A, only the SELV mode is changed to the nonisolated (non-SELV) mode.

Example C: Series connection by use of terminals
The figure below shows an application of a floor-standing luminaire with a linear non-isolated driver OTi DALI 90/220-240V/1A0 LT2 L. It is an example for a series connection by optimal use of the terminals of the OTi (DALI) non-isolated family. All PrevaLED Linear Slim 2 PLSZ2-LIN-1100-840-280 modules are connected in series.

The split of the LED modules does not need to be symmetric as shown below.

Example C: Pinning/connection diagrams: OTi DALI 90/220-240/1A0 LT2 L

Example D: Combined series/parallel connection
Depending on the electrical parameters of the LED module and the selected OT LED driver, different numbers of modules can be connected in series/in parallel to the LED driver. In the non-isolated (non-SELV) case, it is possible to combine parallel and series wiring of LED modules. In a 4-ft luminaire, for example, there are two options to connect the modules:

a) All in series

b) Two in series and two in parallel

The XsYp notation used in OSRAM datasheets gives information on how many modules can be connected to the LED driver. X stands for the number of modules connected in series and Y for the number of modules connected in parallel. For cases a) and b) in a 4-ft luminaire, the corresponding XsYp notations are:

a) All in series - 4s1p

b) Two in series and two in parallel - 2s2p In addition, the datasheets also provide exact wiring diagrams.

Picture: 4-ft non-isolated luminaire – twin lamp

The figure above shows a typical application example for a 1.2-m luminaire with a linear non-isolated driver OT FIT 50/220-240/250 D L. The PrevaLED Linear Slim 2 modules are connected in combined series/parallel connection (4s2p; 4 modules in series, 2 strings in parallel).

Level of control (on/off, different dimming mechanisms)

The level of control in an application ranges from no control (i.e. fixed output) to simple control (i.e. brightness) to full RGB control (i.e. multiple independently controlled channels). Besides the level of control, the preferred control protocol, e.g. 1…10 V, DALI or DMX, must also be selected.

  • CV LED drivers
  • CC LED drivers

Recommended cables for a safe and reliable operation of OT LED drivers is mandatory to use only recommended cables on the input and output side and control port where applicable. This ensures that the cable is suitable for the electrical load and that the mechanical connection of the wire terminals and the cable clamp is safe and working properly.

Cable stripping
Furthermore, to ensure a safe electrical and mechanical connection of the cable in the electrical terminals or the cable clamp, it is mandatory to observe the cable stripping lengths as shown in the figure below. The stripping lengths for (a) and (b) are specified for each pro duct (where applicable) in the respective datasheets.

Cable routing
To ensure good radio interference suppression and maximum safety, the following rules for cable routing should be observed:

  • Mains and LED module cables should never be routed in parallel. Keep output cables and mains cables as far away from one another as possible (e.g. 5 to 10 cm). This avoids mutual interference between mains and secondary-side cables.
  • Place output cables away from earthed metal surfaces (if possible several cm) to reduce capacitive interference.
  • Keep mains cables in the luminaire as short as possible to reduce interference.
  • Do not route mains cables too close to the LED driver (this applies in particular to through-wiring).
  • Avoid crossing mains cables and LED module cables. Where this is not possible, cables should cross at right angles (to avoid HF interference on the mains cable).
  • Cable penetrations through metal components must never be left unprotected and should be fitted with additional insulation (sleeve, grommet, edge protector etc.). Dimming units on the secondary side such as OT DIM usually do not affect the radio interference.