Electromagnetic Compatibility
Grzegorz Kosobudzki, Jerzy
Leszczyński
Emmision of Disturbances
Electromagnetic Compatibility
Grzegorz Kosobudzki, Jerzy
Leszczyński
Emmision of Disturbances
Emmision of disturbances:
• Flicker – rapid voltage fluctuation
• Current harmonics
2
FLICKER - Topics of presentation
• Occurrence of voltage fluctuation and flicker
• flicker measurement circuit
• Flicker formulas
• Time for questions
3
Occurrence of voltage fluctuation and flicker
4
0,24
477,5 H
0,15
(50Hz)
Equivalent impedance of
power distribution system
V
Irms
U
rms
U
rms
Supply is a steady AC
voltage
Equipement’s
fluctuating current
demand
Loads’s voltage
fluctuates due to
fluctuating current
Load
drawing
fluctuating
current
The voltage fluctuation and flicker measurement circuit
5
0,24
477,5 H
0,15
(50Hz)
0,24
477,5 H
0,24
477,5 H
0,16
H
0,1
(50Hz)
Supply source
L1
L3
L2
N
E
q
u
ip
m
e
n
t
u
n
d
e
r
te
s
t
L1
L3
L2
N
Measuring equipment
For a single phase supply L+N impedances
can by combined = 0,4 +j0,25
Resistor 0,4 , inductor 795,8 H
5
Pst and Plt Formulas
3
1
3
N
P
P
N
i
sti
lt
s
s
s
s
s
st
P
P
P
P
P
P
50
5
3
1
1
,
0
08
,
0
28
,
0
0657
,
0
0525
,
0
0314
,
0
Pst
– short-term flicker indicator
Plt - long-term flicker indicator
6
dc and dmax
d
m
a
x
d
c
n
U
t
U )
(
U(t)
10ms
t
1
t
2
t
3
U
c
U
m
a
x
t
d(t)
7
Assesment of relative voltage change
8
dc
– The relative steady-state voltage change
dmax
– maximum relative voltage change
)
(
)
(
2
1
t
U
t
U
U
)
(
)
(
2
1
t
I
t
I
I
j
I
I
q
p
X
I
R
I
U
q
p
Un
U
d
Un
Uc
d
Un
U
d
c
max
max
Method of flicker determination from voltage
fluctuation (EN61000-3-3 figure 4 )
9
Method of flicker determination from voltage
fluctuation (EN61000-3-3 figure 5)
10
Method of flicker determination from voltage
fluctuation (EN61000-3-3 figure 6)
11
Method of flicker determination from voltage
fluctuation (EN61000-3-3 figure 7)
12
Limits (EN 61000-3-3)
13
•Pst < 1;
•Plt < 0,65
•d(t) shall not exceed 3,3% for more then 500ms;
•dc shall not exceed 3,3%
•dmax shall not exceed
a) 4% without additional conditions;
b) 6% switched more frequently than twice per day
c) 7% switched no more than twice per day, and attended
whilst in use, (kitchen equipment, garden equipment, portable
tools)
Flicker - Summary and Conclusion
• How to avoid flicker emissions?
• How to become flicker-proof?
14
Current harmonic emission - topics of
presentation
• Occurrence of voltage harmonic cause by
current harmonics
• Current harmonics measurement circuit
• Clasification of equipment and limits
• Time for questions
15
Harmonic Current emissions
16
i
time
i
time
frequency
frequency
Harmonic Current emissions
17
Impedance of power
distribution system
V
i
u
u
Supply is a pure sine
waveform
Current with harmonic
components
Mains voltage vafeform
is distorted
Nonlinear Load
drawing non-
sinusoidal
current
Harmonic Current emissions
Limits for harmonic current emissions
Equipment input current < 16A per phase
EN 61000-3-2
18
Harmonic Current Emissions Test Stand
19
0,15
(50Hz)
230V AC RMS Pure Sine
Wave Generator
Current
transducer
(impedance
<0,1 )
EUT
L
N
Harmonics analyzer
Supply source – requirements –
EN61000-3-2, annex A
20
•0,9% for harmonic of order 3
•0,4% for harmonic of order 5
•0,3% for harmonic of order 7
•0,2% for harmonic of order 9
•0,2% for even harmonics of order from 2 to 10
•0,1% for harmonics of orders from 11 to 40
Classification of equipment - 1
B – portable tools
C – lighting equipment
D – TV- receiver, PC, computer monitors,
equipment with power consumption les
then 600W
A – balanced three-phase equipment,
household appliances
21
Class
ific
ation of
equipmen
t
-
2
22
Balanced
three-phase
equipment ?
Portable
tool ?
Lighting
equipment ?
Equipment
having the special
wave shape and
P
≤ 600W ?
Class B
Class C
Class D
*Motor
driven ?
Class A
no
no
no
no
no
yes
yes
yes
yes
yes
* Phase angle controlled
Harmonic current limits
23
Harmonic
Class A
Class B
Class C
Clasd D
2
1,08
1,62
2%
-
3
2,3
3,45
30%*PF
3,4mA/W
4
0,43
0,645
-
-
5
1,14
1,71
10%
1,9mA/W
6
0,3
0,45
-
-
7
0,77
1,155
7%
1mA/W
9
0,4
0,6
5%
0,5mA/W
11
0,33
0,495
3%
0,35mA/W
13
0,21
0,315
3%
0,296mA/W
15≤n≤39(odd)
0,15*15/n
0,225*15/n
3%
3,85/n [mA/W]
8≤n≤40(even)
0,23*8/n
0,345*8/n
-
-
Harmonic Current Emissions - Exemple of Measurement
24
Harmonic Emission - Summary and
Conclusion
• How to avoid harmonic emissions?
• How to become harmonic-proof?
25
References and useful links
•
•
•
• C. Sankaran – ”Power quality” – CRC press
2002
• Z.Kowalski – „Jakość energii elektrycznej”
Monografie Politechniki Łódzkiej 2007 (in Polish)
26