Definitions
Voltage quality - Fluctuations and flicker

Voltage fluctuations are either cyclical variations in the RMS voltage value, or random series of voltage jumps. These fluctuations are within the limits of normal voltage variation, i.e. within a tolerance of ±10% of nominal voltage.

There are several types of voltage fluctuations. They are classified as follows in IEC 61000-3-3 (figure 2 ):

• type a: rectangular, periodic voltage jumps of constant amplitude (e.g. switching of resistive loads, resistance welding machines, certain automatic tripping/resetting cycles) ;

• type b: series of irregular voltage jumps. Their...