German manufacturers Rosenberger OSI have launched PreCONNECT PURE®, a novel system for fiber-optic cabling in data centers. PreCONNECT PURE® is an end-to-end system comprising trunk cables, patch cords, SMAP-G2 panels, and racks. The cables are available in multimode and singlemode versions. The limit values Rosenberger OSI allow for insertion loss in the cables and for the quality of the end faces are more demanding than the relevant standards IEC 61300-3-34 und IEC 61755-5 Ed. 1.0 CD. Thus, in contrast to cables compliant with IEC 61755-5 Ed. 1.0 CD Grade Cm, PreCONNECT PURE® 50 µm Multimode in a 16G FibreChannel OM4 channel, for example, allows for twice as many connections and for channels that are up to 15 meters longer. Furthermore, the novel design of the interfaces prevents damage or contamination of the fiber end faces during customization and installation of the cables. This ensures that the high product quality guaranteed by manufacturers Rosenberger OSI is not compromised by faulty installation. Compared to conventional systems, this enables savings in terms of time and cost of up to 15 per cent as there is no need for any on-site acceptance tests or cleaning.
Rosenberger OSI specify PreCONNECT PURE® using the application limit value, which quantifies the level of insertion loss which the connections created by installing or patching a channel will not exceed in any case. This is based on the assumption that connectors and couplers by one single manufacturer are used and that the connectors are free of damages, clean, and professionally installed. The application limit value is usually more suitable for calculating the actual transmission performance than the production limit value specified by many manufacturers. Additionally, the PreCONNECT PURE® quality standard applied by Rosenberger OSI is currently undergoing certification by an independent accredited testing laboratory.
The measuring procedure for the application limit value is standardized according to IEC 61300-3-34. The highest grade of application limit values for 50 µm multimode connections specified by the IEC 61755-5 Ed. 1.0 CD standard is called Cm. In order to reach this grade, insertion loss (IL) may not exceed 0.6 dB for at least 97 per cent of the channels, with a permissible mean insertion loss of 0.35 dB. PreCONNECT PURE® is specified by Rosenberger OSI with a maximum insertion loss of 0.4 dB for 100 per cent of the channels and a mean insertion loss of 0.15 dB. IEC 61755-5 Ed. 1.0 CD also sets a standard for the return loss (RL), which must reach at least 20 dB. For PreCONNECT PURE®, Rosenberger OSI guarantee a return loss of at least 40 dB.
Limit values for the optical quality of the polished end faces of connectors are defined in the IEC 61300-3-35 standard. According to this standard, the core of a multimode cable may have up to four defects, none of which may be bigger than 5 µm. In PreCONNECT PURE®, no defects are allowed at all. The permissible maximum size of scratches is defined by the official standard as 3 µm while the manufacturers’ own standard only allows scratches of up to 2 µm in size. For the other zones of the cable, the PreCONNECT PURE® standard is also less tolerant than the international standards.