IEC 61000-3-2 Electromagnetic Compatibility (EMC) - Part 3-2: Limits - Limits for Harmonic Current Emissions

EUROLAB laboratory provides testing and compliance service within the scope of IEC IEC 61000-3-2 standard. This part of the IEC IEC 61000 standard deals with the limitation of harmonic currents injected into the public supply system. It specifies the limits of the harmonic components of the input current that can be produced by the equipment under test under specified conditions. It is applicable to electrical and electronic equipment having a rated input current up to and including 16 A per phase and intended for connection to general low-voltage distribution systems.

Non-professional arc welding equipment with rated input current up to and including 16 A per phase is included in this document. Arc welding equipment for professional use is excluded from this document as specified in IEC 60974-1 and may be subject to installation restrictions as specified in IEC 61000-3-12. According to this document, tests are type tests. Limits have not yet been taken into account for systems with rated voltages less than, but not equal to, 220 V (line to neutral).

Electronic devices need a smoothed DC voltage as a supply. A 100 or 120 Hz surge in DC voltage is almost unavoidable, especially in the early days of electronics, but can give hum in audio equipment's speakers and vertical, slow-moving dark and light modulation on TV screens. A simple and inexpensive way to achieve low ripple is to use a relatively inexpensive electrolytic capacitor with high capacitance ratings, connected directly after the mains voltage rectifier.

Smoothing of the DC voltage can also be accomplished by inductors, but they are much more expensive and have relatively large size and great weight, but produce much less harmonic current.

IEC 61000-3-2 aims to set limits on the harmonic currents drawn by electrical devices and thus preserve the mains voltage quality. It is a compromise between cost and performance of extra electronic front-end circuits called active power factor correction circuits. With components commonly used today, for example fluorescent lighting ballasts, the cost is relatively low. Although inductors are used in these circuits, they are inexpensive, light and small components with ferrite cores.

Background is given for 50 Hz mains voltage. For 60 Hz the harmonic currents have other frequencies (3:180 Hz, 5:300 Hz) and a half wave lasts 8,33 ms and a typical rectifier smoothing capacitor combination is only 2,5 ms per half cycle (twice per mains). transmits. wave, once on the crest and once in the valley). The hum frequency is 120 Hz.

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