IEC 61000-3-12:2011 pdf free download – Electromagnetic compatibility (EMC)
4.1Determination of the reference current
The average r.m.s. input current shall be measured using the averaging method defined in4.2.2 for harmonic currents. Except for dimmers, the measurement shall be made under theconditions specified in 7.4.For dimmers， the average r.m.s. input current shall be determinedwith the dimmer set to its maximum conduction angle.
The manufacturer may specify any value of r.m.s. current which is within ±10 % of the actualmeasured value and use it as the reference current for the original manufacturer’s conformityassessment test.The measured and specified values of current, as defined in this clause, shallbe documented in the test report.
For emission tests other than the original manufacturer’s conformity assessment test, the valueof the reference current shall be determined as follows. lf the value of the average r.m.s. inputcurrent found by measurement during these emission tests，measured according to the termsof this clause, is not less than 90 % nor greater than 110 % of the value of current specified bythe manufacturer in the test report (see 4.2.6), the reference current is equal to the specifiedvalue. If the new measured value is outside of this tolerance band around the specified value,the reference current is equal to the new measured value.
Table 3,Table 4 or Table 5 can be applied to hybrid equipment in one of the followingcircumstances:
a) hybrid equipment having a maximum 3rd harmonic current of less than 5 % of the reference
current,or
b) there is provision in the construction of hybrid equipment to separate the balanced three-
phase and the single-phase or interphase loads for the measurement of supply currents,and when the current is being measured, the part of the equipment being measured drawsthe same current as under normal operating conditions. in that case,the relevant limitsshall be applied separately to the single-phase or interphase part and to the balancedthree-phase part.Table 3, Table 4 or Table 5 applies to the current of the balanced three-phase part, even if the rated current of the balanced three-phase part is less than or equalto 16 A per phase.Table 2 applies to the current of the single-phase or interphase part, butif the rated current of the single-phase or interphase part is less than or equal to 16 A, themanufacturer may apply the relevant limits of lEC 61000-3-2 to the single-phase orinterphase part instead of the limits stated in Table 2.
For verification purposes, when circumstance b) above applies, the manufacturer shall state inthe product documentation the rated current and give in the test report the measured andspecified values of the input current as defined in 4.1, for each separate load.The value ofRsce for this type of hybrid equipment is determined as follows:
the minimum Rsce value is first determined for each of the two loads，using thereference current of the considered part for the calculation of the harmonic currentemissions to be compared to the limit values given in Tables 2 to 5; in caseIEC 61000-3-2 is applied to the single-phase or interphase part instead of Table 2 limits,the minimum Rsce value for this part is deemed to be equal to 33;
then, for each of the two parts, the minimum value of Ssc is calculated from its minimumRsce value and its rated current (see 3.11 and 3.14);