A Renovation projects: Nancal Electric will recommend the appropriate model through a professional test report that includes all information on system voltage, current, harmonic content, harmonic spectrum, and etc.
New projects: The designer cannot get enough data and can use a simple empirical formula as reference.
a) Distributed compensation: install multiple filters at places near the harmonic sources.
Remarks:
Ih -------- Rated current of harmonic source (loading).
K --------- Load factor, usually set to 1.
THDi ---- Total harmonic current distortion.
b) Centralized compensation: a power filter is installed on the secondary side of the transformer to compensate for harmonics in different branches.
Remarks：
S -------- Rated capacity of transformer.
U -------- Rated voltage of the secondary side of the transformer.
I
h -------- Rated current of harmonic source.
THD
i --- Total harmonic current distortion. Depending on the loading, there are some empirical values for reference. The values for 6-pulse and 12-pulse low voltage inverters are between 30% and 45%.
K -------- Load factor, usually set to 1.
