Newtons4th IMP753 Impedance Network

IEC 61000-3-12 deals with the limitation of harmonic currents injected into the public supply system. The limits given in this International Standard are applicable to electrical and electronic equipment with a rated input current exceeding 16 A and up to and including 75 A per phase, intended to be connected to public low-voltage a.c. distribution systems of the following types:   Nominal voltage up to 240 V, single-phase, two or three wires; Nominal voltage up to 690 V, three-phase, three or four wires; Nominal frequency 50 Hz or 60 Hz. Other distribution systems are excluded. The limits given in IEC 61000-3-12 apply to equipment when connected to 230/400 V, 50 Hz systems. IEC 61000-3-12 applies to equipment intended to be connected to low-voltage systems interfacing with the public supply at the low-voltage level. It does not apply to equipment intended to be connected only to private low-voltage systems interfacing with the public supply only at the medium- or high-voltage level. IEC 61000-3-12 defines: a) Requirements and emission limits for equipment; b) Methods for type tests and simulations. Tests according to this International Standard are type tests of complete pieces of equipment. Conformity with this standard can also be determined by validated simulations. This second edition cancels and replaces the first edition published in 2004 and constitutes a technical revision. The significant technical changes with respect to the previous edition are: The replacement of the reference fundamental current I1 by the reference current Iref for the calculation of emission limits; A newly added table of current emission limits; A newly added annex (Annex A) to define test conditions for some types of equipment; Deletion of the former Annexes B (Approximate interpolation formulas) and D (Information on the PWHD factor). Retrieved 3/12/14 from IEC Webstore Note: Advanced Test Equipment Rentals can perform ISO17025 accredited

IEC 61000-3-3 provides test guidelines for flicker. In the words of the IEC: "This section of IEC 61000-3 is concerned with the limitation of voltage fluctuations and flicker impressed on the public low-voltage system. It specifies limits of voltage changes that may be produced by equipment tested under specified conditions and gives guidance on methods of assessment. This section applies to electrical and electronic equipment having an input current up to and including 16 A per phase and intended to be connected to public low-voltage distribution systems of between 220 V and 250 V at a 50-Hz line to neutral." Although IEC 61000-3-3 is somewhat less controversial than IEC 61000-3-2, the limits are unnecessarily stringent for commercial and industrial environments. IEC 61000-3-11 provides some relief by assessing lower Zref values. Also, many people believe that inrush requirements and test methods are unstable and unjustified. There are some interesting—and even confusing—statements in IEC 61000-3-3. For example, Section 5 states, "If voltage changes are caused by manual switching or occur less frequently than once per hour, the observation-period Pst and Plt requirements shall not be applicable. The long-term observation period, Plt, is flicker severity evaluated over a long period (a few hours) using successive short-term observation-period, Pst, values. Pst is flicker severity evaluated over a short term (in minutes). The three requirements related to voltage changes shall be applicable with the previously mentioned voltage values, multiplied by a factor of 1.33." Further, the specification requires the user to make subjective decisions because of imprecise wording such as that found in Sections 6.1 and 6.5. In any case, this document must be used until a replacement is finished and becomes the standard. Note: Advanced Test Equipment Rentals can perform ISO17025 accredited calibration on products that abide by this