What are Harmonics and Flickers?

Harmonics are distortions of the normal electrical current waveform, usually transmitted by nonlinear loads such as SMPS, IGBT devices, UPS systems (and other devices whose impedance continuously varies during operation) that draw non-sinusoidal, abrupt pulses from a sinusoidal voltage source. Devices that are one of the important parts of a mains supply such as transformers, converters, etc. are prone to harmonic currents. Due to increased harmonic current, the metal wires become hot. This causes several problems such as decreased reliability, damaged insulations, short circuits, the possibility of burning of wires, smoke hazards, and even explosions at some times.

Flickers are the fluctuating current and voltages that cause electrical disturbances with the power supplies. In order to keep voltage distortion to a minimum, electrical products must be able to keep a low harmonic current emission. 

Which EMC Standard is used for Harmonics and Flicker Testing?

IEC 61000-3-2 (Harmonic Current Emissions)

The IEC 61000-3-2 is an EMC standard by the International Electrotechnical Commission on limits for harmonic current emissions applicable 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. This standard specifies the test procedures, limits, and requirements for emissions caused by the harmonic current and its components of the devices. This standard applies to the equipment to be connected to 220/380 V, 230/400 V, and 240/415 V systems operating at 50 Hz or 60 Hz. No limits have been specified for systems with nominal voltage less than 220 V (line-to-neutral).

The IEC 61000-3-2 has classified electronic and electrical equipment into four categories based on the number of pieces of equipment in use, duration of operation, power consumption, harmonics spectrum, etc. 

Which Equipment is used for Harmonic and Flicker Testing?

Following equipment is required for harmonic and flicker testing:

• A 230 V AC power source with low impedance
• Harmonic Analyzer
• Equipment Under Test (EUT)
• Connecting cables

What is the test method for Harmonic and Flicker Testing?

The test set up usually consists of plugging the 230 V power source, the harmonic analyzer and the EUT. According to the IEC 61000-3-2 the EUT is required to run in its normal modes of operation in such a manner that it would create maximum harmonics and flickers it is capable of.  The test readings are not measures until 10 sec and the EUT must not be in a standby mode for more than 10% of the observation period.