When there is excessive harmonic current in power network, it can not only decrease the generator’s efficiency lower, when it is serious, it can also cause the damage of generator and power network, at the same time, it can also affect the normal working of power network user equipment, such as the computer operation error, the roll-over of TV screen.
It is only for the sake of protecting the shared power quality, and make the power network and user equipment running normally, IEC puts forward the limit standard of harmonic current.
Harmonic current test ( harmonic current is an important EMC test project) does not apply to the electronic and electrical products powered by the low pressure AC/ DC and battery of non mains electricity.
3.1 The introduction of measurement standards
A brief introduction for harmonic current is made by taking standard GB17625.1 as an example.
Standard name: GB17625.1-2003 idt IEC61000-3-2:2001
《Electromagnetic compatibility limit the emission limit value of harmonic current (the input current of equipment’s each phase <=16A)》
GB17625.1-2003 is an important standard for authentication and test of many electronic products. The standard is for the measurement and limit of the distortion degree of power supply current waveform when the electronic electrical products (the input current of equipment’s each phase is <=16A) are in the process of using; the electronic electrical products are powered by low pressure mains.
Standard GB17625.1-2003 can limit the equipment’s current waveform distortion by limiting the high order harmonic component of equipment current. GB17625.1 takes the 40th harmonic current content into consideration.