Leakage current of the photovoltaic system, which is also known as the square matrix residual current, is essentially a kind of common mode current. The cause is that there is parasitic capacitance between the photovoltaic system and the earth. When the parasitic capacitance-photovoltaic systemgrid forms a loop, the common mode equipped with a industrial frequency transformer, because of the relatively high parasitic capacitance between the transformer windings in the loop, the common mode current generated by the common mode voltage in the loop can be suppressed to a certain extent. However, in a photovoltaic system with no transformer, the loop impedance is relatively low, and the common mode voltage will form a large common mode current, ie, leakage current, on the parasitic capacitance between the photovoltaic system and the earth.
Hazard of leakage current
If the leakage current in the photovoltaic system, including the DC part and the AC part, is connected to the grid, it can cause problems such as grid-connected current distortion and electromagnetic interference, so as to affect the operation of the equipment in the grid. In addition, leak current can also electrify the solar inverter casing, thus threatening physical safety.
Standard and detection of leakage current
According to the 7.10.2 regulation of NB32004-2013 / IEC 62109-1:2010 standard, in any case where the solar inverter is connected to the AC grid and the AC breaker is turned off, the inverter should provide leak current detection. Leak current detection should be able to detect the total (including the DC and AC parts) effective value current, continuous residual current.
Sinomag's residual current detection sensors not only meet the requirements of the solar industry, but wherever a leakage current has to be detected in order to avoid damage to a system or even danger to people, these products are a precise and cost-effective solution.