Terminal blocks pass insulation testing for photovoltaic applications

Testing ensures that terminals can withstand a continuous voltage of 1000 V dc under all climatic conditions. Specialized insulation testing is required for solar photovoltaic (PV) applications because standard insulation tests do not detect low-energy (partial) discharges, which are common in PV applications.

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Weidmuller announces the completion of specialized insulation testing on its terminals blocks geared specifically for solar photovoltaic (PV) applications. This testing ensures that terminals can withstand a continuous voltage of 1000 V dc under all climatic conditions. Specialized insulation testing is required for PV applications because standard insulation tests do not detect low-energy (partial) discharges, which are common in PV applications. Partial discharges can slowly work through a terminal’s insulation line, ultimately causing a defect. In addition, insulation lines react differently to partial discharge tests for dc voltage than to partial discharge tests for ac voltage.  Since solar panels generate dc electricity, only terminal blocks that have passed a partial discharge test for dc voltage are suitable for safe use in photovoltaic systems. 

To maximize the power generated by a PV system, solar panels that convert solar energy to dc electricity are connected in series or in parallel to create solar arrays.  Arrays are connected to a dc-to-ac converter (solar inverter) via a combiner box.  The combined voltage from the arrays within a combiner box may be as high as 1,000 V dc in global applications, or 600 V dc for NAFTA applications requiring UL certification.  It is critical that terminal blocks used within a combiner box are able to safely and reliably withstand these voltages. 

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Weidmuller

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- Edited by Renee R. Bassett for Control Engineering, www.controleng.com