Limits
Limits for harmonic current emissions (equipment input current ≤16 A per phase)
Scope
This part of IEC 61000 deals with the limitation of harmonic currents injected into the public supply system.
Harmonic components are measured according to annexes A and B.
Arc welding equipment which is not professional equipment, with input current up to and including 16 A per phase, is included in this standard.
NOTE 1 :It is intended to replace technical report IEC 61000-3-4 by an international standard, IEC 61000-3-12 (under consideration).
NOTE 2 :The words apparatus, appliance, device and equipment are used throughout this standard. They have the same meaning for the purpose of this standard.
General
The objective of this standard is to set limits for harmonic emissions of equipment within its scope, so that, with due allowance for the emissions from other equipment, compliance with the limits ensures that harmonic disturbance levels do not exceed the compatibility levels defined in IEC 61000-2-2.
Professional equipment that does not comply with the requirements of this standard may be permitted to be connected to certain types of low voltage supplies, if the instruction manual contains a requirement to ask the supply utility for permission to connect. Recommendations concerning this aspect are contained in IEC/TS 61000-3-4.1)
Classification of Equipment
For the purpose of harmonic current limitation, equipment is classified as follows:
Class A :
• balanced three-phase equipment;
• household appliances, excluding equipment identified as class D;
• tools, excluding portable tools;
• dimmers for incandescent lamps;
• audio equipment.
Equipment not specified in one of the three other classes shall be considered as class A equipment.
NOTE 1 : Equipment that can be shown to have a significant effect on the supply system may be reclassified in a future edition of the standard. Factors to be taken into account include:
• number of pieces of equipment in use;
• duration of use;
• simultaneity of use;
• power consumption;
• harmonic spectrum, including phase.
Class B :
• portable tools;
• arc welding equipment which is not professional equipment.
Class C :
• lighting equipment.
Class D :
Equipment having a specified power according to 6.2.2 less than or equal to 600 W, of the following types:
• personal computers and personal computer monitors;
• television receivers.
NOTE 2 : Class D limits are reserved for equipment that, by virtue of the factors listed in note 1, can be shown to have a pronounced effect on the public electricity supply system.
The procedure for applying the limits and assessing the results is shown below.
Harmonic current limits
The procedure for applying the limits and assessing the results is shown in figure 1.
For the following categories of equipment, limits are not specified in this standard:
NOTE 1 : Limits may be defined in a future amendment or revision of the standard.
• equipment with a rated power of 75 W or less, other than lighting equipment;
NOTE 2 : This value may be reduced from 75 W to 50 W in the future, subject to approval by National Committees at that time.
• professional equipment with a total rated power greater than 1 kW;
• symmetrically controlled heating elements with a rated power less than or equal to 200 W;
• independent dimmers for incandescent lamps with a rated power less than or equal to 1 kW.
NOTE 3 : See also C.5.3.
Limits for Class A equipment
For Class A equipment, the harmonics of the input current shall not exceed the values given in table 1.
Audio amplifiers shall be tested according to clause C.3. Dimmers for incandescent lamps shall be tested according to clause C.6.
Limits for Class B equipment
For Class B equipment, the harmonics of the input current shall not exceed the values given in table 1 multiplied by a factor of 1,5.
Limits for Class C equipment
a) Active input power >25 W
For lighting equipment having an active input power greater than 25 W, the harmonic currents shall not exceed the relative limits given in table 2.
However, the limits given in table 1 apply to incandescent lighting equipment that has built-in dimmers or consists of dimmers built in an enclosure.
For discharge lighting equipment that has built-in dimmers or consists of independent dimmers or dimmers built in an enclosure, the following conditions apply:
• the harmonic current values for the maximum load condition derived from the percentage limits given in table 2 shall not be exceeded;
• in any dimming position, the harmonic current shall not exceed the value of current allowed in the maximum load condition;
• the equipment shall be tested according to the conditions given in C.5.
b) Active input power ≤25 W
Discharge lighting equipment having an active input power smaller than or equal to 25 W shall comply with one of the following two sets of requirements:
the harmonic currents shall not exceed the power-related limits of table 3, column 2, or:
• the third harmonic current, expressed as a percentage of the fundamental current, shall not exceed 86 % and the fifth shall not
exceed 61 %; moreover, the waveform of the input current shall be such that it begins to flow before or at 60°, has its last peak (if
there are several peaks per half period) before or at 65° and does not stop flowing before 90°, where the zero crossing of the
fundamental supply voltage is assumed to be at 0°.
If the discharge lighting equipment has a built-in dimming device, measurement is made only in the full load condition.
Limits for Class D equipment
For Class D equipment, the harmonic currents and the power shall be measured as defined in 6.2.2. The input currents at harmonic frequencies shall not exceed the values that can be derived from table 3 according to the requirements specified in 6.2.3 and 6.2.4.
Table 1 Limits for Class A equipment
Table 3 Limits for Class D equipment
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