## 5 Results  
### Harmonic Emissions  
The levels of emission in the harmonic frequency range generated by individual devices supplied with different voltage levels are represented graphically. The measurements are done according to EN61000-3-2 standard [16] supplied voltage does not include background harmonics ( \(THD_{v}\approx\) 0%). The various colored bars represent graphically the selected current harmonics in the percent value of the fundamental component 50 Hz systems (in comparison to the fundamental harmonic of 100%). Figure 3a shows the harmonic spectrum for the CFL 20 W lamp with no-PFC topology (PF = 0.6). It consists mainly of third, fifth and seventh harmonics, circa 80%, 50% and 25%, respectively, (in comparison to the fundamental harmonic of 100%). For the lower frequencies (up to 650 Hz), the voltage level variation within the range of 210-250 V with a step of 10 V observable impacts the level of emission. With increasing supply voltage, harmonic current emission becomes more severe. The exception is the 9 th harmonic component, for which voltage variation does not influence the amplitude change. The level of successive odd harmonics above 650 Hz (13 th harmonic component) decreases to finally reach circa 5% of the fundamental component for the 40 th harmonic in 50 Hz systems. LED bulbs represent nonlinear loads since they contain diodes in their topology. Analysis of the harmonic spectrum for the LED 7 W lamp, equipped with a passive-PFC topology (PF = 0.85) and supplied in variable voltage (series of steps from 210 V to 250 V), is shown in Figure 2b. The emission severity of successive odd harmonics up to the 15 th is significant. The highest amplitude of disturbance reaches the third harmonic (c. 15% of the fundamental component). For the 5 th, 9 th, 11 th and 13 th components, an increase in supply voltage results in an increase in emission level. For the 15 th harmonic, in contrast,the supply voltage gradually increases from 210 V to 250 V and the disturbance marginally decreases. For the 7 th and above 17 th odd harmonic, the level of disturbances is not sensitive to changes in supply voltage. Based on different values of the voltage supplied by the LED 8 W lamp equipped with active-PFC topology (PF = 0.92), Figure 2c illustrates the distortion level of the input current waveform in the harmonic frequency spectrum. In terms of power factor, this topology has a high efficiency (PF \(>\) 0.9) [56] but the device has an advanced control power supply circuit with switching devices that shape the input current waveform and insert harmonic pollution. The highest amplitude reaches the third harmonic (c. 18% of the fundamental harmonic component of 100%). The severity of successive odd harmonics is lower and does not decrease proportionally (the 5 th harmonic \(\approx\) 9%, the 7 th harmonic \(\approx\) 6%, the 9 th harmonic \(\approx\) 4%, the 11 th harmonic \(\approx\) 2%, whereas the 13 th and 15 th harmonics \(\approx\) 4%). Starting with the 15 th harmonic current, the severity of the harmonic current does not decrease proportionally. In the case of the examined LED bulb with active-PFC topology, the influence of supply voltage level variation on the harmonic emission level is significant. The most visible difference is in the third harmonic, the emission severity is a practically linear function of supply voltage. When the voltage is increased from 230 V to 240 V and then 250 V the disturbance also increases by around 2%. Analogically, when the supply voltage is decreased from 230 V to 220 V and then 210 V the amplitude level of the third harmonic decreases by around 3%. The total difference in the severity of this harmonic is 5% between the minimum and maximum levels of supply voltage. For the 7 th, 9 th, 11 th and 13 th harmonics, an analogous relation can be observed. The level of the fifth harmonic does not significantly change when the supply voltage is varied. The exception is the 15 th harmonic component.