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

•

www.lpqi.org

•

www.miedz.org.pl

•

www.reo.co.uk

• C. Sankaran – ”Power quality” – CRC press

2002

• Z.Kowalski – „Jakość energii elektrycznej”
Monografie Politechniki Łódzkiej 2007 (in Polish)

26