WCA November 2015

• Special developed polymer as separator • Separable layers which have been required by many customers (UL definition: “Thermoset insulation having a jacket”) • The difference of these two cable families are different layers thicknesses because the UL has a higher requirement for the insulation thickness • All compounds are thermoset (electron beam crosslinking)

3.3.1 The differences to TUV 1169/2007.8 The significant differences between UL and TUV are: • Halogenated compounds are permitted in UL4703 • The required flaming test UL1581-1060 is more demanding than IEC60332-1 • No differentiation between DC and AC in UL4703 • 1,000V (or 2,000V) is permitted, which is more future-orientated • Aluminium wires are permitted in UL4703 • No differentiation U0/U in UL4703

5 The next step 5.1 New requirements

In 2013 the new requirement of the PV industry was to increase the system voltage to save cable cost and to increase the efficiency of the PV systems. The voltage rating of the first generation of PV wires according to TUV1169 was based on generic industrial cable standards. The standard voltage rating of low voltage cables in the CENELEC and IEC is U0/U = 600/1,000V AC or 900/1,500V DC. The nominal voltage rating of the new generation photovoltaic wire is U0/U = 1,000/1,000V AC or 1,500/1,500V DC. In the meantime TUV Rheinland developed 2Pfg1990/2012, which considers the new requirements.

GND

❍ ❍ Figure 2 : Definition of U 0 /U

4 New challenge for the cable industry 4.1 TUV and UL approved cables 2006–2013 In 2006 the module manufacturers started to think globally. The new marketing requirement was to manufacture one type of photovoltaic module with all relevant approvals to sell them on all markets. The challenge was to create a cable which could combine the opposed specifications of UL (PV / USE-2) and TUV 1169. Particularly the following discrepancies had to be overcome. • Halogen-free compounds are highly filled with flame retardant minerals. The physical properties required by UL are a challenge for this kind of compound • Passing the flame test required by UL is easy for halogenated compounds but difficult for halogen-free compounds • The long-term stability test of UL is a real challenge for filled compounds because the flame-retardant additives are hygroscopic However, it was possible to comply with all these requirements.

Two-layer jacket optimised for mechanical properties and flame retardance Two-layer insulation. Electrical properties and flame retardance Conductor

❍ ❍ Figure 4 : New design

5.2 New generation of UL4703 1,000V/TUV 1,500V DC cables The outstanding characteristics of this design are: • Four-layer extrusion in one pass (implicated by further increasing pricing pressure in the PV industry) • All compounds are thermoset (electron beam crosslinked) • Layers not separable (UL definition: “Composite insulation without a jacket”) • Approvals: UL (1,000V)/TUV (2Pfg1990)/CSA 22.2 No 271-11 6 The way to CENELEC and IEC 6.1 CENELEC In 2011 the German National Committee for PV wires and cables started to work out a revision of VDE-AR-E 2283-4 “Requirements for cables for PV systems”. The target was now to apply this draft as a new work item to CENELEC TC20. The main topics were: • Increasing the system voltage • Adapting test procedures to the new voltage level The result of this work is EN50618, which was published as a final draft in August 2014.

Jacket Separator Insulation Conductor

4.1.1 The first solution The outstanding characteristics of this design are: • Three-layer extrusion in one pass (implicated by increasing pricing pressure in the PV industry) ❍ ❍ Figure 3 : Optimised design of a UL4703 and TUV1169 or TUV1169 wire

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Wire & Cable ASIA – November/December 2015