Terminal blocks for 1,000 VDC applications

During the installation of photovoltaic modules, individual panels are switched in series in „strings“ as a means to achieve higher system voltages. Weidmüller terminal blocks are suited for this application because they have passed a specialised insulation test. The test checks to see if the terminals can withstand a continuous voltage of 1,000 VDC under all climatic conditions.

This examination of the insulation lines allows for the identification of microscopic discharges which can over days, weeks or even years work through an insulation line, thus finally causing an insulation defect. Classical insulation tests do not detect these low-energy discharges. Therefore, only terminal blocks which have passed a partial discharge test for direct current voltage are suitable for the safe use in photovoltaic systems.

Application-specific surge protection solution for a photovoltaic system.

Insulation lines react in a totally different way to partial discharge tests for DC voltage than to partial discharge tests for AC voltage. That is to say, the individual consideration of the insulation thickness, the terminal’s dimension, or other physical features does not allow any conclusions regarding the terminal block’s qualification for 1,000 VDC applications. For direct current applications, the features of the terminal blocks rather have to be considered in combination. This is why Weidmüller has decided to separately approve every individual terminal type for this kind of application. A list of all such approved Weidmüller terminal blocks can be inspected here.