Download Detection of selected EMI Sources in the Prototype of LED Street Light

Detection of selected EMI Sources in the Prototype of LED
Street Light
(Full text in English)
Bystrík DOLNÍK1, Michal ŠPES1
1Technical
University of Košice, Faculty of Electrical Engineering and Informatics, Department of Electric Power Engineering
Abstract
The improvement of LED components in parameters such as efficiency, thermal resistance or operating life enables
to use these excellent properties in applications such as spot lights, street light, automotive headlamps etc.
However, the use of these new technologies is closely associated with the essential requirements related to
electromagnetic compatibility. The paper is focused on the electromagnetic compatibility of a prototype of LED
street light with various drivers. As a basis for analysing of the compliance with EMC standards the requirements for
the harmonic content of input line current and power line conducted emissions was used. The results obtained from
experiments pointed to the fact that some of the voltage drivers are incompatible with requirements for the
harmonic content of input line current. The problem is caused mainly by two factors: improper circuit design of the
LED driver, or bad design of the LED driver with respect to the rated load.
Keywords: EMC, LED light, power quality, emission, voltage driver
Received: December, 20, 2015
1. Introduction
Electric equipment and systems are always
subjected to electromagnetic disturbance. The
location and layout of power components, cable
routing, shielding, etc. are important right from the
initial design phase. Also any electric equipment is,
itself, an electromagnetic disturbance generator.
Circuits with electronics are becoming more and
more sensitive and the distance between victims
(sensitive circuits) and sources (disturbing circuits)
are becoming smaller. Disturbances cause
undesirable phenomena and mitigation is
necessary. Although, the equipment offers
satisfactory EMC, a well-designed electric
equipment with installation can extend the
compatibility safety margins. Moreover, it must
also be noted that only measurements requiring a
high level of expertise and sophisticated equipment
can produce valid results quantifying the EMC of
equipment. Currently, in addition to the EMC of
technical systems, the interest in the EMC of
biological systems is growing [1], [2], [3].
Undesirable effects, e.g. transformer heating,
transformer
secondary
voltage
distortion,
increased power losses and others may be caused
by harmonic currents in the power distribution
system [4]. Existing penetrations of small single
phase loads can create problems that require
mitigation. There are two ways to address the
harmonics issues. The first is the traditional method
of mitigating problems after they adversely affect
utilities and their customers. In this case, the
mitigation expense is usually borne by the owner of
the equipment causing the harmonic problem, or by
those affected by it. The other option for
addressing harmonics issues is to reduce the
consumption of harmonic currents by changing the
design of the loads, that is, constant frequency
power system exists and connected loads should be
limited in their consumption of harmonics. The
limiting philosophy affects mostly electronic
equipment using rectifier power supplies for the
reason that the rectifier power supplies in those
devices consume high levels of harmonic currents.
The limiting philosophy require additional
investment and the return on that investment is low
[5], [6].
2. Lighting system based on LED technology
One of the great benefits from widespread high
brightness LEDs for general illumination is the
reduction of energy consumption. About 50 % of the
energy spent on artificial light could be saved,
which represents more than 10 % of the global
energy consumption [7]. An LED street light based
on a 901 mW output LED can normally produce the
same amount of luminance as a traditional light,
but requires only half of the power consumption.
The lifetime of LED street light is usually 10 to 15
years, three times the life of current technologies
adopted.
Whereas a time span of 10 years, with a total of
43800 hours of system operation, the only light
sources that do not need to be replaced are the
LEDs lamps [8]. An LED street light is an integrated
light-emitting diode (LED) light fixture that is used
for street lighting. These are considered integrated
lights because, in most cases, the luminaire and the
fixture are not separate parts. The current trend is
to use high power 1 watt LEDs. The shape of the
LED street light depends on several factors,
ELECTROTEHNICĂ, ELECTRONICĂ, AUTOMATICĂ (EEA), vol. 64 (2016), nr. 2
including LED configuration, the heat sink used with
the LEDs and aesthetic design preference. The area
of heat exchange directly affects the lifespan of the
LED street light. Most LED street light have a lens
on the LED panel designed to cast the light in a
rectangular pattern [9], [10].
2.1 Advantages of LED street light
An advantage compared to traditional street
lights is less light pollution in the air and
surrounding environment and limited glare for
drivers and pedestrians. An LED street light dispose
with full brightness instantly and do not have a
problem restarting immediately. Some other
advantages of the LED street light are e.g. more
accurate colour rendering makes it easier for
drivers to recognize potential road hazards, less
attractive to nocturnal insects, don't release
poisonous gases if damaged, don't contain harmful
substances, like mercury or lead, fewer electric
losses, optically efficient lighting equipment,
environmentally friendly, recyclable and easily
controllable with intelligent systems. White light
sources have been shown to double driver
peripheral vision and increase driver brake reaction
time at least 25 %.
Studies in Europe have demonstrated that street
lighting has a significant effect on the mood of
human beings, animal life and the environment. It
affects navigation of birds and insects, mating
behaviour in animals and flowering in plants. The
impact of LED lights on animals is much smaller
compared to other lights [11], [12].
2.2 Disadvantages of LED street light
Disadvantages of LED street light are: the initial
cost is high, a luminance level higher than
10000 cd/m2 causes visual discomfort whatever the
position of the lighting unit in the field of vision,
the replacement of traditional street lighting with
LED street light is leading to a major change in the
colour of the urban sky glow, high temperatures (in
the order of 100 °C) reduce the LED’s life time
significantly [13], [14].
2.3 Human eye response on different levels of
light
The eye is one of the most sophisticated and
developed sense organs in humans with high
sensitivity and accuracy in the perception of
reflected light by objects around us. Human eyes
are not able to reveal everything. They can see only
objects that emit or are illuminated by light waves
in our perception ranging from 380 nm to 780 nm,
approximately. Human vision is enabled by three
primary modes:
− Photopic vision: Human visual response to
daylight, or luminance greater than 1 cd/m2
(under high luminance levels above 3 cd/m2).
We see objects in full color.
55
− Scotopic vision: Monochromatic vision in very
low light. Scotopic vision occurs at a luminance
level of about 0.01 cd/m2 and it relies mostly
upon rod receptors and color sensitivity peak is
blue-green. This luminance is about equivalent
to a full moon. A human sees objects in black
and white.
− Mesopic vision is a combination of photopic
vision and scotopic vision in low lighting ranging
from 1 cd/m2 down to 0.01 cd/m2.
The human colour sensitivity peak is moving
between green and blue. The dependence of human
relative sensitivity on the wavelength is shown in
Figure 1. Under these conditions the vision
functions due to a combination of rod and cone
cells in the eye. Although all three modes of vision
help us see under different conditions, night-time
vision is generally dominated by scotopic
mechanisms for very dark conditions with no
ambient light, or mesopic mechanisms for semidark conditions, e.g. during the full moon.
Figure 1. The standard eye response in logarithmic
scale
Human vision doesn't immediately switch from
daylight to dark vision (photopic to scotopic). It
takes about 30 minutes for the eye to transition
from fully light to fully dark adapted [7], [15].
3. Requirements on LED street light
The LEDs are a part of a dynamic system in the
LED street light with the main control mechanism
being the LED driver. The LED driver for highbrightness LEDs is usually implemented with a
switching converter. The driver adapts to the everchanging dynamics to continuously provide
regulation, electrically stabilizing the system. The
current changes rapidly with forward voltage across
an LED in its operating region. The brightness of an
LED is proportional to the forward current.
3.1 Power supply
The best way to supply LEDs is to control the
forward current in order to satisfy the LED
manufacturer’s characteristics (lumens and colour
temperature). Linear current sources may be used,
but power dissipation becomes excessive when the
supply voltage is significantly higher than the
forward voltage of the LED. A switched mode power
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ELECTROTEHNICĂ, ELECTRONICĂ, AUTOMATICĂ (EEA), vol. 64 (2016), nr. 2
One of the main goals in the design of the street
light power supply is in correcting of the harmonic
distortion of the input line current so that the
harmonic content was reduced below the limits
specified in the relevant standards. For the LED
street light applies European standard EN 61000-32, Class C at full load and nominal input voltage
network [17], [20], [21]. Since the power supplies
for LED street light work mostly in the switching
mode, it is necessary to test these sources to
conducted emission according to EN 55015.
Harmonic line current reduction can be
achieved by using different techniques. The most
common used techniques for harmonic current
reduction are line filters, using passive
components, and active electronic circuitry.
Harmonic line current reduction using passive
components (inductors and capacitors) introduces
high impedance for the harmonics thus smoothing
the input current to electronic equipment.
Harmonic line current reduction using active
electronic circuitry is shaping the input current of
an electronic equipment proportional to the
applied line voltage thus giving a sinusoidal input
current in phase with the line voltage. The
corresponding electronic circuitry is often called
power factor correction (PFC) circuitry [22].
certain points from the standards for households
and industry [20].
European standard EN 55015 sets forth
procedures for the measurement of radiofrequency disturbances and limits within the
frequency range of 9 kHz to 400 GHz and applies to
all lighting equipment with a primary function of
generating and/or distributing light intended for
illumination purposes, and intended either for
connection to the low voltage electricity supply or
for battery operation. EN 55015 is a product family
standard (largely based on CISPR 15) [20], [23],
[24], [25]. Key EMC standards include EN 61000-3-2
for limits on harmonic current emissions, EN 610003-3 for limits on voltage changes, voltage
fluctuations and flicker, and EN 61547 for immunity
requirements. Suppliers could be asked to provide
substantiation or warranty on compatibility
between the driver and the LED lighting. European
standard EN 61000-3-2 applies to all electric and
electronic equipment that has an input current of
up to 16 A per phase, suitable for connection to the
low-voltage AC public mains distribution network.
This standard does not apply to (and has no limits
for): non-public networks, non-lighting equipment
with rated power of 75 W or less, equipment for
rated voltages less than 230 V AC (limit not yet
been considered), arc welding equipment intended
for professional use, professional equipment (not
intended for sale to the general public) with rated
power greater than 1 kW, heating elements with
symmetrical control methods and input power less
than or equal to 200 W, independent dimmers for
incandescent lamps with rated power less than or
equal to 1 kW.
There are 4 different classes in the EN 61000-32 that have different limit values: Class A: Balanced
3-phase
equipment,
household
appliances
excluding equipment identified as Class D, tools,
excluding portable tools, dimmers for incandescent
lamps, audio equipment, and all other equipment,
except that stated in one of the following classes.
Class B: Portable tools, arc welding equipment
which is not professional equipment. Class C:
Lighting equipment. Class D: PC, PC monitors,
radio, or TV receivers. Input power P ≤ 600 W. For
Class C equipment having an active power greater
than 25 W the maximum permissible harmonic
currents are given as a percentage of the
fundamental input current.
3.4 EMC
4. Experiment
Currently, there is a sharp increase in the use of
electronic modules in lighting technology. This is
due to several factors, including the decision of the
European Union (EU) to abolish the use of
incandescent
lamps
by
2012,
continued
development of low-pressure and high-pressure
discharge lamps and the progress in the
luminescent power of LEDs. Special standards apply
with respect to EMC and interference, and differ in
The experiment realized on the LED street light
was focused on the power line conducted emissions
and harmonic current emissions. The European
standards applied in the experiment are the
following: EN 55015:2013 Limits and methods of
measurement of radio disturbance characteristics
of electric lighting and similar equipment and EN
61000-3-2:2006 Limits for harmonic current
emissions (equipment input current up to and
supply with constant current output is the best
choice to achieve highest system efficiency [16],
[17].
3.2 Power factor
Power factor represents an important
parameter because a high power factor decreases
losses in the power distribution network. The most
effective way to reduce the environmental impact
of electricity use is to minimize waste. The
manufacturers of LED lamps and luminaires are
responding to these demands and naturally want
their products to be as universal in application as
possible. So they are calling for the LED driver
circuits to perform with all types of dimmer units
at high efficiency and power factor greater than
0.9. For these reasons a street light power supply
designed to power an LED street light must have
high efficiency and at least a similar lifetime, in
order to guarantee the maintenance free operation
required by these kinds of applications [18], [19].
3.3 Harmonic distortion
ELECTROTEHNICĂ, ELECTRONICĂ, AUTOMATICĂ (EEA), vol. 64 (2016), nr. 2
including 16 A per phase). Limits for Class C are
shown in Table 1.
Table 1: Limits for Class C equipment
Harmonic order n
2
3
5
7
9
11 ≤ n ≤ 39
Harmonic current
2
30 × PF
10
7
5
3
The harmonic current in Table 1 represents a
maximum permissible harmonic current expressed
as a percentage of the input current at the
fundamental frequency, the PF abbreviation stands
for power factor and the condition in the last row
of the table applies to the odd harmonics. The
nominal electric power of LED street lights was 30
W, 50 W and 60 W. A total of seven drivers for LED
lamps used as LED street light were tested.
4.1 Test procedure
As mentioned above, the measurements of
power line conducted emissions were carried out
according to EN 55015. The EUT is put on the table
which is 0.8 m high above the ground and
connected to the AC mains through a Line
Impedance Stabilization Network (L.I.S.N.). The
L.I.S.N. provides a 50 Ω coupling impedance for the
tested equipment and spectrum analyser with
frequency range from 20 Hz to 26.5 GHz. Both sides
of AC line (line and neutral) are checked to find out
the maximum conducted emission according to the
EN 55015 regulations during conducted emission
measurement. As regards the measurement of
harmonic current emissions, the testing was
conducted according to the circuit diagram in
Figure 2, where S is the power supply source, ZS is
the internal impedance of the supply source, M is
the measurement equipment, U is the test voltage,
ZM is the input impedance of measurement
equipment, In is the harmonic component of order
n of the line current and G is the open-loop voltage
of the supply source.
The data acquisition used during testing was set
to 200 ms with no gap or overlap between the
acquired data blocks. All measurements employed
the 1.5 s first order filter before the averaging
calculation is processed for each block of data.
When measuring single-phase electric system,
which is also the case, the standard EN 61000-3-2
allows to measure current harmonics on neutral
conductor.
Figure 2. Single-phase measurement circuit
57
Otherwise, the current harmonics must be
measured on the phase conductors. The nominal
voltage was set to 230 V. The current harmonics
were computed by using of the Fourier transform.
The main idea of transformation lies in the fact that
the linear periodic signal can be replaced by a
superposition of simple harmonic functions. The
Fourier-type sum is represented as follows:
9+Z. = OH3 O cos+TZ ; }O .
Ÿ
(1)
f(t) is time dependent periodic function, O is
amplitude, }O is phase shift of the T-th harmonics,
T is the number of harmonics ( T ∈ ) and is
angular frequency. This form of a general
trigonometric sum has the advantage of displaying
explicitly the amplitude and phase of each
harmonic. Using mathematical manipulations, the
Fourier-type sum can be expressed as follows:
Ÿ
9+Z. Y3 ; OH: YO cos+TZ. ;
Ÿ
(2)
; OH: <O sin+TZ.
For the amplitude of the T-th harmonics O in
(1) applies as follows:
O YOX ; <OX tan }O ¢£¤ ¥¦
§¨¢ ¥¦
(3)
N¦
•¦
(4)
In addition to the real form of equation (1)
harmonic waveform can be expressed using phasor
̅ +Z. in the complex plane, which rotates at a
constant angular frequency in the form:
̅ +Z. O e«+O–r¥¦ . (5)
For direct transformation is
Ÿ
+. ¬Ÿ 9+Z.0 ­– Z
(6)
Inverse transformation has the form
9+Z. : Ÿ
¬ +.0 ­–  X® Ÿ
(7)
f(t) is time dependent periodic function and
F( ) is spectrum. The measurement instrument
process, the current flowing through the LED driver
so, that is composed of samples taken at regular
intervals of time. Harmonic currents are computed
using Discrete Fourier transform with the most
efficient way through the Fast Fourier transform
algorithm.
4.2 Evaluation methodology
The limits of the mains terminal disturbance
voltages for the frequency range 9 kHz to 30 MHz
are given in Table 2. The limit decreases linearly
with the logarithm of the frequency in the ranges
50 kHz to 150 kHz and 150 kHz to 0,5 MHz.
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58
Table 2: Limits of radio disturbance characteristics
Frequency range
(MHz)
0.009-0.05
0.05-0.15
0.15-0.50
0.50-2.51
2.51-3.0
3.0-5.0
5.0-30.0
Limits (dBµV)
Quasi-Peak
110
90-80
66-56
56
73
56
60
Average
56-46
46
63
46
50
The limits of the mains terminal disturbance
voltages for the frequency range from 9 kHz to
30 MHz are given in quasi-peak values, while the
limits of the mains terminal disturbance voltages
for the frequency range from 150 kHz to 30 MHz are
given in average as well as in quasi-peak values.
The limits for harmonic current emissions
(EN 61000-3-2) are applicable to electric and
electronic equipment having an input current of up
to 16 A per phase and connected to public lowvoltage distribution systems. The limits are
specified for each class. For the Class C the
classification is made according to the active power
of the equipment (for single-phase equipment, the
classification is made using the active power of the
single-phase power). The limits for harmonic
current emissions, Class C and equipment with
active input power exceeding 25 W are shown in
Table 1.
Table 3: Measured harmonic current emissions of the
first 60 W LED driver – Class C, power factor
PF = 0.444
Harmonic order n
2
3
5
7
9
11
Harmonic current
(%)
2.46
89.71
84.12
76.39
66.89
56.38
Multiple of limit
1.23
6.74
8.41
10.91
13.38
18.79
The power factor for the measured LED driver is
0.444 and corresponding limit for the 3rd harmonics
is 13.32 %. In the third column of the Table 3 the
multiples of limits are calculated.
The corresponding average THD of the current
generated by the first 60 W LED driver is equal to
181.33 %, the maximal THD is 181.73 %. Figure 4
shows the time course of the terminal voltage and
current flowing into the first 60 W LED driver.
5. Results
In the experiment, the power line conducted
emissions Class A and Class B and the harmonic
current emissions for Class C were observed. The
power line conducted emissions measured on the
first 60 W LED driver are shown in Figure 3.
Figure 4. Time course of the terminal voltage and
current flowing into the first 60 W LED driver
Finally, Figure 5 shows the THD of the current
through the 60 W LED driver and corresponding PF
measured for the first 2500 minutes of
measurement.
Figure 3. Limits and measured level of the conducted
emissions on the first 60 W LED driver
between phase conductor and earth
The level of the conducted emission was
measured with peak detector in frequency range
from 9 kHz to 150 kHz and from 150 kHz to 30 MHz.
The harmonic currents generated by the first 60 W
LED driver are listed in the Table 3.
Figure 5. THD and PF measured on the first 60 W LED
driver in phase conductor
In Figure 6, the power line conducted emissions
measured on the 50 W LED driver are shown. Type
ELECTROTEHNICĂ, ELECTRONICĂ, AUTOMATICĂ (EEA), vol. 64 (2016), nr. 2
of the measuring detector and the frequency range
is the same as in the Figure 3.
Figure 6. Limits and measured level of the conducted
emissions on the 50 W LED driver between
phase conductor and earth
The harmonic currents generated by the 50 W
LED driver are listed in the Table 4. The power
factor for the measured LED driver after 600
seconds of operation is 0.991 and corresponding
limit for the 3rd harmonics is 29.73 %. As already
indicated in the Table 3, in the third column of the
Table 4, a multiples of the permitted limits for
individual harmonics are given.
59
and corresponding PF measured for the first 600
minutes of measurement.
Figure 8. THD and PF measured on the 50 W LED driver
in phase conductor
The power line conducted emissions measured on
the second 60 W LED driver are shown in Figure 9.
Table 4: Measured harmonic current emissions of the
50 W LED driver – Class C, power factor
PF = 0.991
Harmonic order n
2
3
5
7
9
11
Harmonic current
(%)
0.13
7.30
4.83
4.13
3.13
2.35
Multiple of limit
0.065
0.246
0.483
0.590
0.626
0.783
The corresponding average THD of the current
generated by the 50 W LED driver is equal to
10.73 %, the maximal THD is 10.77 %. Figure 7
shows the time course of the terminal voltage and
current flowing into the 50 W LED driver.
Figure 9. Limits and measured level of the conducted
emissions on the second 60 W LED driver
between phase conductor and earth
The harmonic currents generated by the second
60 W LED driver are listed in the Table 5.
Table 5: Measured harmonic current emissions of the
second 60 W LED driver – Class C, power
factor PF = 0.456
Harmonic order n
2
3
5
7
9
11
Figure 7. Time course of the terminal voltage and
current flowing into the 50 W LED driver
Finally, Figure 8 shows the trend over time of
the THD of the current through the 50 W LED driver
Harmonic current
(%)
2.78
90.12
84.13
75.85
65.78
54.74
Multiple of limit
1.39
6.56
8.41
10.84
13.16
18.25
The power factor for the measured LED driver is
0.456 and corresponding limit for the 3rd harmonics
is 13.68 %. In the third column of the Table 5 the
multiple of limit are calculated. The corresponding
average THD of the current generated by the
second 60 W LED driver is equal to 179.14 %, the
maximal THD is 179.46 %.
60
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6. Discussion
The power line conducted emissions measured
on the first 60 W LED driver depicted in Figure 3
shows that the level of emission of the LED driver is
below the limits specified in the standard EN 55015.
All the measurements of power line conducted
emissions were made by using of a spectrum
analyser according to EN 55015 with the detector
set to a peak value in the whole frequency range.
The measured data of emissions were evaluated
according to standardized limits for the quasi-peak
values. Margin of emission ranges from 50 dB to 30
dB at low frequencies, whereas at high frequencies,
the margin of emission ranges from 20 dB to 10 dB.
Margin of emission strongly depends on the type of
the converter and its mode of operation. Increased
emissions are near the following frequencies:
50 kHz, 75 kHz, 15 MHz and 27.5 MHz.
From the Table 3, it is clear that the first 60 W
LED converter exceeds all permissible limits for
harmonic current emissions. This fact is confirmed
by the time course of the terminal voltage and
current flowing into the first 60 W LED driver shown
in Figure 4. Measured values of the odd harmonics
extremely exceed the specified limits thus resulting
high value of THD of the supply current and low
power factor, also.
From Figure 6, it is clear, that the power line
conducted emissions measured on the 50 W LED
driver are below the limits specified in the standard
EN 55015. Compared to the first 60 W LED driver
can be seen increased emissions in the frequency
range from 1 MHz to 15 MHz. As for the harmonic
current emissions, 50 W driver complies the
requirement on the limits specified in the standard
EN 61000-3-2 with a sufficient margin, see Table 4.
This fact is confirmed by the time course of the
terminal voltage and current flowing into the 50 W
LED driver shown in Figure 7, the low value of the
THD of the supply current and high power factor
shown in Figure 8, also.
Finally, the power line conducted emissions
measured on the second 60 W LED driver depicted
in Figure 9 shows that the level of emission of the
LED driver is below the limits specified in the
standard EN 55015. Increased emissions are near
the following frequencies: 50 kHz, 75 kHz and
17 MHz. From the Table 5 it is clear that the second
60 W LED driver exceeds all permissible limits for
harmonic current emissions. Measured values of the
odd harmonics extremely exceed the specified
limits thus resulting high value of THD of the supply
current and low power factor, also.
From the time courses of the terminal voltage
and current flowing into the LED driver in Figure 4
and Figure 7, it is evident that the terminal voltage
is an ideal sine wave. This requirement is ensured
by measuring circuit as recommended in the EMC
standard. The power supply voltage must have
extremely low harmonic distortion in order to
eliminate the generation of harmonics into the
measuring circuit. Is clear that the time course of
the current in Figure 4 is periodic but does not have
a sinusoidal shape. The deformation of the current
waveform is caused due to harmonic currents
emission from the LED driver. The contrary
represents the time course of the current in
Figure 7, which is also periodic but has a much
lower harmonic distortion resulting in a more
similar to the sine waveform.
This fact has already been commented with
respect to the THD of the supply current and power
factor. In the experiment, significant differences in
the time course of the instantaneous power were
observed.
A typical case shown in Figure 10 represents the
comparison of the time course of instantaneous
power consumed by the LED drivers with different
power factors and THD of the supply current.
Figure 10. The time course of instantaneous power
consumed by the LED driver with power
factor of 0.991 and power factor of 0.444
As can be seen, in both cases, the instantaneous
power period is shorter by half. This corresponds to
double of industry frequency. A significant
difference is in the fact that instantaneous power
of the LED driver with high power factor is similar
to a sine waveform, while instantaneous power of
the LED driver with low power factor is similar to
impulse mode. In this case, the impulse mode is
undesirable to ensure the EMC of the harmonic
currents.
7. Conclusions
The detection of selected sources of
electromagnetic interference in the prototype of
LED street light was realized. For this purpose, two
types of emission measurements on LED street
lights were investigated: the power line conducted
emissions according to the standard EN 55015 for
Class A and Class B, and the limits for harmonic
current emissions for Class C according to the
standard EN 61000-3-2. A total of seven drivers for
LED street light with nominal electric power 30 W,
50 W and 60 W were tested.
The results obtained from measurements of the
power line conducted emissions have pointed to the
fact that increased emissions were detected at
frequencies of 50 kHz, 75 kHz, 15 MHz, 17 MHz and
27.5 MHz. By comparing the measured data, it can
ELECTROTEHNICĂ, ELECTRONICĂ, AUTOMATICĂ (EEA), vol. 64 (2016), nr. 2
be concluded that all LED drivers comply with the
standard EN 55015 with a sufficient margin and are
not sources of increased interference. As for the
harmonic current emissions the measurements have
shown the shortcomings of some drivers. The
reason lies in the fact that permissible limits
according to the standard EN 61000-3-2 were
extremely exceeded. Moreover, in these cases, high
levels of THD of the supply current and low power
factors were measured. Only on two LED drivers low
harmonic current emissions, low value of the THD
of the supply current and high power factor were
measured. It was found that the problem of
harmonic current emissions is due to either
improper circuit design of the LED driver, or bad
design of the LED driver with respect to the rated
load of the LED street light.
8. Acknowledgment
This work was financially supported by the Scientific Grant
Agency of the Ministry of Education of the Slovak Republic and
Slovak Academy of Sciences, under the scientific Project
“Analysis of changes of electro-physical structure of progressive
electric insulating materials due to external degrading factors”
No. 1/0311/15, “Research on the penetration of high-frequency
electromagnetic field through the ecological construction
materials.” No. 1/0132/15 and the Ministry of Education,
Science, Research and Sport of the Slovak Republic, under the
Project “Innovation of the Laboratory of Electromagnetic
Compatibility and Innovation in the Content, Forms and Methods
of Practical Exercises of the Electromagnetic Compatibility
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9. Biography
Bystrík DOLNÍK was born in Handlová
(Slovakia), on October 16, 1967.
He graduated the Technical University of
Košice, Faculty of Electrical Engineering
(Slovakia), in 1992.
He received the PhD degree in electrical
engineering and high voltage engineering
from the Technical University of Košice (Slovakia), in 1996.
He is Assistant professor at the Technical University of Košice,
Košice (Slovakia).
His research interests concern: overvoltage, overvoltage
protection, computer aided design simulation, accelerated
ageing tests and electromagnetic compatibility.
Correspondence address: Technical University of Košice,
Faculty of Electrical Engineering and Informatics,
Department of Electric Power Engineering, Mäsiarska 74,
04120 Košice, Slovakia, [email protected]
Michal ŠPES was born in Stará Ľubovňa
(Slovakia), on November 16, 1991.
He graduated the Technical University of
Košice, Faculty of Electrical Engineering
(Slovakia), in 2015.
He is PhD student at the Technical University
of Košice, Košice (Slovakia).
His research interests concern: electric machines, protection
relays and power line ampacity.
Correspondence address: Technical University of Košice,
Faculty of Electrical Engineering and Informatics,
Department of Electric Power Engineering, Mäsiarska 74,
04120 Košice, Slovakia, [email protected]