This article presents a study of compact fluorescent lamps (CFLs) low energy consumption lamps found in the Cameroonian market. The current obtained in the experimental setup has been analyzed in Matla b Simulink. The results obtained show that the THD of different lamps does not respect the standard IEC-61000-3-2. These values increase with the power of lamps. Spectral analysis of these lamps shows that the probable cause of their premature degradation results from the effects of harmonics on the capacitors. This degradation is all more precocious as the rank and the concerned THDi is great. That’s why 75 W lamps are more sensitive than others.
Deficit electric energy in the world and mainly in Africa has led states to adopt energy efficiency policies. These policies concern production and consumption fields. Consumption of electrical energy by electric lighting is estimated at 20% world consumption. To reduce this, Cameroonians have chosen low-energy lamps. Among these, we find mainly LED lamps and compact fluorescent lamps (CFLs) with electronic ballast. The lifespan ranging of CFL is estimated between 6000 h and 15,000 h but in pratic we observe a premature deterioration of these. Analysis of power supplies of these faulty lamps shows that they are RCD (resistor, capacitor and diodes) types [
Harmonics are the sinusoidal voltages or currents whose frequency is an integer multiple of frequency network (50 hz in Cameroon) called fundamental. A signal polluted is a superposition of this different harmonics that can modeled by following equation:
f ( t ) = a 0 + ∑ n = 1 ∞ ( a n cos ( n w t ) + b n sin ( n w t ) ) (1)
where n is harmonic rank and w = 2 Π T the electric pulse
a 0 , a n , b n , are real constants with:
a 0 the average value of the electrical signal given by:
a 0 = 1 T ∫ T f ( t ) d t
a n the real part of signal amplitude
a n = 2 T ∫ T f ( t ) cos ( n ω t ) d t
b n the imaginary part of signal amplitude
b n = 2 T ∫ T f ( t ) sin ( n ω t ) d t
For n = 1 we have the fundamental.
Main harmonics perturbations causes are nonlinear charges. They are generated by equipment (electronics components) who supply by DC current. computers, variable speed drives and CFLs are examples. This load type is characterized by generation of deformed current which remains periodic and created sequences zero harmonics like: rank 7 and 13 witch are sequence positive; rank 5 and 11 witch are sequence negative; rank 3 and 9 witch are sequence zero [
Electric characteristics of a periodic signal deformed are:
• The total rms value
If I k is rms value of harmonic current at rank k, the total rms value is given by Equation (2)
I r m s = ∑ k = 1 n I k 2 (2)
•The individual harmonic distortion rate
It gives relation between rms value of harmonic and the fundamental
T H D i % = I K I 1 × 100 (3)
•Total harmonic distortion
It characterizes signal distortion rate, their expression is given by Equation (4)
T H D % = ∑ k = 2 n I k 2 I 1 × 100 (4)
•The harmonic spectrum
It consists of determining magnitude or THDI (voltage or current) at different signal harmonics rank. the spectral density gives similar information.
• The power factor
It is ratio between active power (P) and apparent power (S). It does not translate difference phase between voltage and current of load. Equation (5) give their expression:
λ = P S (5)
•The distortion factor
It is ratio between power factor and difference phase between current and voltage. It characterizes deformation of the phase shift. If it equal to one, it means that signal has not harmonics. It is given by Equation (6)
ν = λ cos φ 1 (6)
With φ 1 phase shift between voltage and current at the fundamental
• The distortion power
The presence of Harmonics in signal create a power distortion given by following relation [
D 2 = S 2 − P 1 2 − Q 1 2
where P 1 and Q 1 are active and reactive powers at the fundamental.
Harmonics have several effects in the electric network equipment’s, including [
• The heating of cables by joule effect, translated by following equation:
Perte = r ∑ k = 1 n I k 2 (7)
With r the cable resistance.
This heating also concerns the protective conductor if spectrum is rich in rank 3 harmonic.
• Destruction of capacitors
Capacitor current is given by following relation:
I = 2 Π k f C U (8)
where k is the harmonic rank and f the fundamental frequency.
This current increases with the harmonic rank. If capacitor is connected parallel with a transformer or an inductor it can enter resonance at the corresponding eletric pulsation given by Equation (9)
w k 2 = 1 L C (9)
With w k = 2 Π k f
Apart from these consequences we can cite: the nuisance tripping of circuit breakers, sources disturbance, sensitive electronic equipment and others.
To limit harmonic pollution several standards and directives on electromagnetic compatibility are imposed. These are presented in
Like any device electric, CFLs lamps must comply with IEC 61000-3-2 standard, which states that harmonics emission limits for lamps are subdivided according to their active power (
| Standards | Description |
|---|---|
| IEC-61000-2-2 | Compatibility Levels for Low Frequency Conducted Disturbances and Signal Transmission in Low Voltage Distribution Networks |
| IEC-61000-2-4 | Compatibility levels for low-frequency disturbances in industrial installations |
| IEC-61000-3-2 | Limitation of harmonic current emissions (equipment with input current less than 16 A per phase) |
| IEC-61000-3-4 | Limits for harmonic current emissions on low-voltage networks for equipment with a rated current greater than 16 A. |
| IEC-61000-3-12 | Limits for harmonic currents produced by equipment connected to public low-voltage networks with input currents greater than 16 A and less than or equal to 75 A |
| Power less than 25 W. one of these 2 limits applies | Power greater than 25 W | ||
|---|---|---|---|
| % of the fundamental current | Harmonic current in relation to the active power | % of the fundamental current | |
| 3 | 86 | 3.4 ma/W | 30 |
| 5 | 61 | 1.9 ma/W | 10 |
Investigation we carried out focused on 3 lamps whose characteristics are given in
Measurement of current absorbed by lamps was carried out using the experimental setup shown in
Experimental setup consists of the following elements:
• Connection box to connect lamps and different elements of the bench;
• Switch for switching lamps;
• Computer (output interface) for viewing electrical signal;
• VOLCRAFT digital oscilloscope interface connected to computer;
• A measuring probe; A shunt for currents measurement through voltages image.
Signal coming from oscilloscope (computer) being noisy,
Voltages at the terminals of our different shunt are presented in
| Power (W) | Voltage (V) | Frequency (Hz) | Life time (h) | |
|---|---|---|---|---|
| 20 | 220 - 240 | 50 - 60 | 8000 | |
| 40 | 220 - 240 | 50 - 60 | 8000 | |
| 75 | 220 - 240 | 50 - 60 | 8000 |
We note that obtained measurements are quite noisy hence need to filter for better exploitation. After measurement, signal obtained are processing on matlab simulink platform. Results are presented in
Currents obtained are less noisy. Their different THD are presented in
It is found that THD increases with the lamps power. values obtained are much higher than the 3% predicted by standard for class C equipment. Analysis of spectral density gave the following results in
| Lamp | THD (%) |
|---|---|
| 20 W | 68.99 |
| 40 W | 82.94 |
| 75 W | 116.04 |
We note that at each harmonic rank, THDi increase with power of lamps. According to the IEC-61000-3-2 standard only the 20 W lamp is in adequacy with standard (
| Rank of the harmonic | THDi lamps (%) | ||
|---|---|---|---|
| 20 W | 40 W | 75 W | |
| 1 | 100 | 100 | 100 |
| 3 | 37.5 | 58.3 | 64 |
| 5 | - | 8.83 | 30 |
| 7 | 10 | 16.6 | 37 |
| 9 | - | 4.16 | 40 |
This article investigates the harmonic pollution of CFLs lamps in order to diagnose the causes of premature degradation of these lamps. For this purpose, experimental setup has been set up to carry out the various tests. Noisy signal obtained was filtered and analyzed in the Matlab Simulink platform. Obtained results show that harmonic spectrum of investigated lamps mainly comprises harmonics of zero sequence. THD obtained increases with power as well as THDi. Comparison of different results with IEC-61000-3-2 IEC standard shows that only the 20 W lamp is inadequacy at the harmonics 3 and 5. High rate of these THDs suggests that the rapid deterioration cause of these type lamps are effects of harmonics on the capacitors (Equations (8) and (9)).
The authors wish to express their sincere thanks to research team in Electrical Energy System of University of Douala.
The authors declare no conflicts of interest regarding the publication of this paper.
Perabi Ngoffe, S., Ndjakomo Essiane, S., Offole, F., Mengata Mengounou, G., Moukengue Imano, A. and Onambele (2019) Harmonic Investigation of Compact Fluorescent Lamps Low Energy Consumption Lamps of Cameroonian Market. Open Access Library Journal, 6: e5446. https://doi.org/10.4236/oalib.1105446