The calculation of harmonic current involves many factors, and for conventional projects, a power quality analyzer can be used to calculate harmonic current. For new projects, electrical designers during the design phase may not be able to obtain sufficient harmonic data from electrical equipment; In view of this, based on testing and experience summary of numerous industries, Energy Capacity Electric has obtained empirical formulas for electrical designers to refer to.
The following empirical formula can meet the design requirements; Select ZRYYLB based on the calculated harmonic current;
1. Centralized governance
be careful:
The above formula is applicable for centralized treatment on the secondary side of transformers.
Formula parameter introduction:
S: Rated capacity of transformer; U: Rated voltage on the secondary side of the transformer;
I: Harmonic current; THDi: Total harmonic distortion rate of current.
K: Load rate;
The load rate of the transformer is represented, with a value range of 0.6~0.85 during transformer design.
THDi is the only variable in the above equation, and its value range depends on the different industries and the different loads of each industry.
2. On site governance
The above formula is designed for the centralized treatment of harmonics on the secondary side of transformers. Here, it is recommended that designers carry out treatment on the secondary side of transformers. If there is a high-power harmonic source load in the distribution system, on-site treatment can also be carried out at the input end of the load. The following formula 2 can be used for calculation.
