EMI-Filter CNW 173

As a result of the ever more efficient energy conversion in modern power inverters, ever more high-frequency energy is being introduced into DC circuits. This energy is caused by the quick switching operations of modern power semi-conductors and could cause the premature aging of solar modules. REO-DC mains filters work in both directions. In practical usage, this means that the end devices are protected against unnecessary high frequencies. On the other side however, the power network is also protected against the spreading of self-generated high frequencies by the end devices. In the frequency range of 150kHz – 30MHz, a very high interference level occurs on both the AC and DC sides. This circumstance is not currently addressed in the standards for the DC side. The connected long DC cabling and the large-area PV modules represent a unique feature that distinguishes inverters from all other electronic devices. The PV generator and the often very long DC lines act as antennas and can radiate originally conducted interference. The electromagnetic compatibility of inverters with other devices must be ensured.