1 UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. EMC Europe 2016 Wroclaw International Symposium and Exhibition on Electromagnetic Compatib September 5-9, 2016, Wroclaw, Poland Kees Post Lambda Engineering B.V. [email protected]Frits Buesink [email protected]EMC for LARGE Installations EMC Europe 2016, Wroclaw, Poland 2 Contents EMC for LARGE installations 1 Introduction to Electromagnetic Compatibility (EMC) Essential Requirements and Standardization 2 The physics of Electromagnetic Interference (EMI) How does it work and how to measure it? 3 Electromagnetic Phenomena Electromagnetic Environmental Effects (E 3 ) 4 Measures against interference coupling Building Electromagnetic Environments (divide & conquer) 5 Compatibility of Large Systems Organization of EMC and Reducing Complexity 6 Conclusions and recommendations The research leading to these results has received funding from the European Union on the basis of Decision No 912/2009/EC, and identified in the European Metrology Research Program (EMRP) as Joint Research Project (JRP) IND60 EMC, Improved EMC test methods in industrial environments. Additional funding was received from the EMRP participating countries UNIVERSITY OF TWENTE. TELECOMMUNICATION ENGINEERING. Lambda Engineering B.V. Acknowledgements
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1
UNIVERSITY OF TWENTE.TELECOMMUNICATION ENGINEERING.
EMC Europe 2016 Wroclaw International Symposium and Exhibition on Electromagnetic CompatibSeptember 5-9, 2016, Wroclaw, Poland
1 Introduction to Electromagnetic Compatibility (EMC)
Essential Requirements and Standardization
2 The physics of Electromagnetic Interference (EMI)
How does it work and how to measure it?
3 Electromagnetic Phenomena
Electromagnetic Environmental Effects (E3)
4 Measures against interference coupling
Building Electromagnetic Environments (divide & conquer)
5 Compatibility of Large Systems
Organization of EMC and Reducing Complexity
6 Conclusions and recommendations
The research leading to these results has receivedfunding from the European Union on the basis ofDecision No 912/2009/EC, and identified in theEuropean Metrology Research Program (EMRP)as Joint Research Project (JRP) IND60 EMC,Improved EMC test methods in industrial environments.Additional funding was received from the EMRPparticipating countries
UNIVERSITY OF TWENTE.TELECOMMUNICATION ENGINEERING.
Lambda Engineering B.V.
Acknowledgements
2
EMC Europe 2016, Wroclaw, Poland 3
Introduction
EMC for LARGE installations
“The ability of the System to Operate according to its Specificationsin its Intended Electromagnetic Environment” [IMMUNITY]
“Without generating Unacceptable Electromagnetic Disturbancesinto that Environment” [EMISSION]
Definition of EMC
Sou
rce:
You
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e
EMC Europe 2016, Wroclaw, Poland 4
Three Criteria for EMC
1. No (intolerable) emissions into the environment
2. Operate satisfactorily in its EM environment
So
urce
:Y
ouT
ube
EMC for LARGE installations
3. Not cause interference with itself3. Not cause interference with itself
3
EMC Europe 2016, Wroclaw, Poland 5
Systems Perspective: Performance Criteria
EMC for LARGE installations
what happens when immunity threshold levels are approached?
ASystem continues to work according to specificationDegradation not acceptableGenerally applies to all interference with a continuous nature
BTemporary degradation acceptable, auto recovery.Usually applies to sporadic interferenceto a non-critical function.
C Degradation acceptable. Recovery after manual RESET.e.g. at mains interruptions. Only for non-critical functions. A
n U
NS
AF
Esi
tuat
ion
is n
ever
acc
epta
ble
!
EMC Europe 2016, Wroclaw, Poland 6
The necessary elements for an interference situation
EMI, ElectroMagnetic Interference model: source – victim and coupling path
Source Victimcoupling path
Coupling path: always electrical interconnections
to tiny.
EmissionSusceptibility
(Immunity)
Very large….
this can be demonstrated using: a noise generator a radio receiver and some cables
Deviations in EM levels, gaps in technical standards
Different environments
Different installation practices
Very high EMC margin
WarningThis product complies with the requirements in accordance with product standard IEC 61800-3. In a domestic environment, this product may cause radio interference, in which case supplementary mitigation measures may be required.
WARNING: Screened cables must be used with this equipment in order to comply with the EMC Directive 2004/108/EC regulations
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 12
Understanding the Physics of Electromagnetic Effects
passive components and their (ideal) behavior in the time domain
RResistor
VR
IR
·
described by(behavioral model)
Ohm’s Law
LCoil
VL
IL
·
described by
CCapacitor
VC
IC
described by
·
EMC for LARGE installations
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EMC Europe 2016, Wroclaw, Poland 13
Ideal Components do not Exist
all components have, so called, “parasitics”
EMC for LARGE installations
RResistor C
Capacitor
LCoil
EMC Europe 2016, Wroclaw, Poland 14
Any current needs a magnetic field!
field of the return conductor is identical but opposite (if geometry is identical)
EMC for LARGE installations
H = Magnetic Field [A/m] - H
Ir
rH
2
Biot Savart’s Law:
8
EMC Europe 2016, Wroclaw, Poland 15
Current carrying conductor always exhibits H‐field
minimize fields by aligning conductors (not possible for twin wires)
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 16
Special Cable Geometries
COAX produces less fields than twin wires (under conditions)
EMC for LARGE installations
I
I
ONLY if shield currentuniformly distributed
over 360°
Special care when mountingconnectors or glands!
9
EMC Europe 2016, Wroclaw, Poland 17
Special Cable Geometries
make sure, current over shield can be uniformly distributed over 360°
EMC for LARGE installations
I
I
ONLY if shield currentuniformly distributed
over 360°
Source: Smythe W.R.“Static and Dynamic Electricity”p. 278. McGraw Hill, 1950
EMC gland with provision for 360° contact
EMC Europe 2016, Wroclaw, Poland 18
“Pig‐tails” Destroy Good Coax Properties
effect of geometry changes: fields outside interconnections; CM currents
EMC for LARGE installations
whencompared…
“Coax is betterthan
twin wires”Coax
Twinwires
Pig-tail destroys cable symmetry
Fields aregenerated
10
EMC Europe 2016, Wroclaw, Poland 19
Induction in a Single Wire
current in a conductor is only possible when a magnetic field exists
EMC for LARGE installations
50
coax cable
single wire
1. Waveform for fast edge
A B
A
B
signal integrity =no distortion onthe signal line
EMC Europe 2016, Wroclaw, Poland 20
Induction in a Single Wire
current in a conductor is only possible when magnetic field exists
EMC for LARGE installations
50
coax cable
1a. Waveform for fast edge@ reduced loop area
A B
A
B
Reduce loop area:less time and energy
needed to build H-field
single wire
11
EMC Europe 2016, Wroclaw, Poland 21
Induction in a Single Wire
current in a conductor is only possible when magnetic field exists
EMC for LARGE installations
50
coax cable
single wire
2. Waveform for slow edge
A B
A
B
EMC Europe 2016, Wroclaw, Poland 22
Simulation of Wire Inductance Demonstration
in LTSpice IV
EMC for LARGE installations
12
EMC Europe 2016, Wroclaw, Poland 23
All Currents Run in Loops
Kirchhoffs Current Law: basic for the design of component networks
EMC for LARGE installations
I1 I2
I3
Ia Ib
Kirchhoff’s electrical current law
213 III
ba II
Every current musthave a return path!
As a Designer,
ask yourself:
Where does my
Return Current
Flow?
EMC Europe 2016, Wroclaw, Poland 24
Common‐mode currents dominate the EMC arena
currents, generated by cables’ “desired currents” into CM or ground‐loop
EMC for LARGE installations
Source Load
“Ground”
“Differential-mode” currentIdm
Icm
“Common-mode” current
CM: 99%of all EMIproblems!
Common-mode current is thatpart of the return current which
follows a different path thanthe designers intended route
CM-currentscan becreated
“elsewhere”
13
EMC Europe 2016, Wroclaw, Poland 25
Demonstration of the Common Mode Current
using the three demonstration cables of slide 1
EMC for LARGE installations
50
source (50)
scope
“ground” litz wire
Any Cable
50
amplitude depends on cable quality
Current clamp
EMC Europe 2016, Wroclaw, Poland 26
“Common‐Resistance” Crosstalk
resistance in the common return path of two loops (SPICE model)
EMC for LARGE installations
source current
· 1
Isource
Inoise
14
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Resistive Crosstalk Waveform
linear operation: noise signal shape is identical to source waveform
EMC for LARGE installations
SourceWaveform
NoiseWaveform
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Kirchhoff Electrical Voltage Law
assumes all fields are inside the circuits components
EMC for LARGE installations
Kirchhoff’s Voltage Law
Us
R1
R2
UR1
UR
2
021 RRS UUU
loop 1flux flux
Faraday’s Law:
?
15
EMC Europe 2016, Wroclaw, Poland 29
Mutual induction: coupling of circuits (loops)
Field loop 1 induces voltage in loop 2 (“Crosstalk”‐ or: transformer)
EMC for LARGE installations
I1
loop 1
loop 2
MModel:
flux 1
1
212
loop
loop
IM
1
11 I
L
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Substitute source model for inductive crosstalk
Faraday’s Law expressed in the time and frequency domain
EMC for LARGE installations
loop 1
loop 2
flux 1
1
212
loop
loopM
1
11
L
Faraday’s Law:Faraday’s Law:
Vnoise
22
looploop
noise jdt
dV
or
112112
looploop
noise Mjdt
dMV
1122 looploop M
Vnoise
I1
Note: capacitive modelyields current source
Voltagesource
16
EMC Europe 2016, Wroclaw, Poland 31
Substitute source model for inductive probes
Faraday’s Law for a Loop Probe
Faraday’s Law:
Vloop
Vloop
Voltagesource
looploop
loop jdt
dV
or
looploop
loop AHjdt
AHdV
Loop Area, Aloop
External Magnetic Field H
HBDensityFlux r 0
looploop ABFlux
1, airr
m
H70 104
rtyPermeabiliMedium 0
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 32
Inductive probe for Magnetic Fields: the Model
derivation using a substitute voltage source
air gap inshielding
semi-rigid coax
chip resistor 50 (sometimes left out)
Area: A
Magnetic Field: H
instrument:50
Principle ofOperation:
MutualInduction
ABFluxCoupled HBDensityFlux
EMC for LARGE installations
17
EMC Europe 2016, Wroclaw, Poland 33
Alternative Shape: Current Clamps/Probes
current clamps use ferrite cores to guide magnetic field through coil
C-shaped Core
C-shaped Core
Both cores are clamped together aroundthe current conductor to be measured
Coil:90 turns of0.5 [mm] wire
Conductor/Current to be measuredmust be led through toroid
Coil:Fill toroid with
wire turns(Most sensitive)
MModel:
Principle ofOperation:MutualInduction
Current in Wire“to be measured”
IMFluxCoupled
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 34
Small Magnetic Sniffer Probe
5‐turn loop probe using ferrite to concentrate flux lines
Coil:5-6 turns of0.5 [mm] wire
Small C-shaped core
Conductor under test(or external field)
Usable for lower frequencies:• more sensitive than single loop probe• ferrite concentrates magnetic field lines
Note for Loop and Sniffer Probe
The probe output voltage is proportional to Bort
B
Hence, the MIL-STD-461 calls it a “B-dot” probe
EMC for LARGE installations
18
EMC Europe 2016, Wroclaw, Poland 35
Operation of the current probe
derivation using a substitute voltage source
R=50
Lprobe
Equivalent circuit diagram:
R=50
Measurement setup:
Vout
MjVind
probe
probeout
LR
j
LR
MjV
probeL
R
probeL
R MjVout
ML
RV
probeout
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 36
Operation of the current probe
graphical representation of results
probeC L
R
low frequencycut-off of probe
Calibrationlevel:
probeL
MR
Current probe: = M.Loop probe: = B.ANote
R = 50 Measure Lprobe
Calculate C
EMC for LARGE installations
19
EMC Europe 2016, Wroclaw, Poland 37
SPICE Simulation of an Inductive Probe
With LTSpice IV
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 38
Calibrating the Current Probe
use the following setup
coax cable
B
single wire
50 A 50
Current Probeunder test
Sine wave generator
Probe
Probe = VChannel A /50
VOutProbe = VChannel B
Make table for frequencies:
0.1, 0.2, 0.5, 1, 2, 5,10 kHz etc.
EMC for LARGE installations
20
EMC Europe 2016, Wroclaw, Poland 39
Simulate Current Probe in LTSpice
model the frequency dependent source using a transformer
The source I1 is the“current to be measured”,set as 1 Amp (no DC)
A transformer is usedto model the “frequencydependent source”Coupling Factor K1 = 1
http://www.linear.com/designtools/software/LTSpice IV (free on the Internet):
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 40
Examples of “home made” magnetic field probes
useful if professional equipment is unavailable
Current Clamp(separable)
magnetic field probe
Current Clamp(fixed)
EMC for LARGE installations
21
EMC Europe 2016, Wroclaw, Poland 41
Mutual induction in practice
two circuits with a common return (“ground”) conductor
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
50
B
50
A
EMC Europe 2016, Wroclaw, Poland 42
Mutual induction in practice
crosstalk created by mutual induction between two loops
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
Only a change in current produces crosstalk!
50
dt
dIVnoise ~
B
50
A
22
EMC Europe 2016, Wroclaw, Poland 43
Mutual induction in practice
“common return” = common impedance, largely inductive
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
50
B
50
A
EMC Europe 2016, Wroclaw, Poland 44
Mutual induction in practice
slower risetimes = less crosstalk
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
Note that a slower rise timeproduces less or no crosstalk at all!
50
dt
dIVnoise ~
B
50
A
23
EMC Europe 2016, Wroclaw, Poland 45
Mutual induction in practice
thin line: two adjacent loops: high mutual inductance!
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
50
“Mutual inductance” also knownas “Common-Impedance”
B
50
A
EMC Europe 2016, Wroclaw, Poland 46
Mutual induction in practice
solution 1: reduce loop area of source
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
50
B
50
A
24
EMC Europe 2016, Wroclaw, Poland 47
Mutual induction in practice
solution 1a: also reduce area of victim loop
EMC for LARGE installations
source (50)
scope
“ground” litz wire
single wire (source)
single wire (passive)
50
B
50
A
EMC Europe 2016, Wroclaw, Poland 48
Ground Plane
Wide ground plane is preferredreturn path for current!
Mutual induction in practice
solution 2: wide return conductor (ground plane)
EMC for LARGE installations
source (50)
scope
single wire (source)
single wire (passive)
50
B
50
A
25
EMC Europe 2016, Wroclaw, Poland 49
Ground Plane
Mutual induction in practice
proximity effect: return current concentrates under “red” wire
EMC for LARGE installations
source (50)
scope
single wire (source)
single wire (passive)
50
Icm “squeezes”under cable
(proximityeffect)
B
50
A
Separation of “loops” becomes much easier!
victimloop
sourceloop
EMC Europe 2016, Wroclaw, Poland 50
Proximity effect
current concentrates under conductor, minimizing loop inductance
EMC for LARGE installations
Current concentrates underconductor (proximity effect)
R=50R=50
Field distribution can bemeasured with smallsniffer probe
x
J(x)
26
EMC Europe 2016, Wroclaw, Poland 51
Return Current Distribution Magnitude in Ground Plane
lowering the wire reduces volume “filled with flux”
The ESD contact discharge current waveform (IEC 61000-4-2)
EMC for LARGE installations
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Time to frequency domain conversion
two characteristic frequencies appear related to pulse duration and rise time
A
50%
90%
10%
h
r
Fknee
h 1
r 1
r2
1
F1 F2
ampl
itude
log (frequency)
f
1~
2
1~
f
EMC for LARGE installations
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EMC Europe 2016, Wroclaw, Poland 121
ESD pulse can be decomposed into two trapezoids
this allows an estimate of the ESD current frequency spectrum
0 2 108
4 108
6 108
8 108
0
5
10
15
20Building blocks contact discharge pulse
time [s]
curr
ent [
A]
IS i( )
IF i( )
I i( )
t i( )
Short and long pulse added in the time domain
Fast pulse: r=0.7 ns; h=10 ns
Slow pulse: r=10 ns; h=60 ns
To convert the ESD pulseto frequencies, it can besplit into two trapezoids
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 122
Spectra of slow and fast pulse can be added
the resulting spectrum is used for shielding analyses
1 106
1 107
1 108
1 109
1 1010
1 1010
1 109
1 108
1 107
1 106
1 105
ESD current spectrum
frequency
curr
ent c
ontr
ibut
ion Iesd i( )
IesdS i( )
IesdF i( )
f i( )
Total current
Sum
Fast pulse
Slow pulse
EMC for LARGE installations
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EMC Europe 2016, Wroclaw, Poland 123
Inductive load switching
Relays, Valves, and PWM motor control systems
V0
SW
L
C(parasitic)
R(parasitic)
Basic model
0
2
2
1 LEnergy
par
2
2
1VCEnergy
22
2
1
2
1VCL
L= 0.1 HC= 100 pF = 1 A
V = 32 kV (!)
Analysis:
Source: Jasper J. Goedbloed, “EMC”Prentice Hall/Kluwer 1992
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 124
High Voltage in Switch Arcs and Creates Spikes
reason for Electrical Fast Transients (EFT) tests on equipment
ampl
itude
time (s scale)
breakdown (ns scale)
from EN 61000-4-4
5/50 ns pulses
EMC for LARGE installations
63
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Lightning Electromagnetic Pulse (LEMP)
Sou
rce:
You
Tub
e
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 126
Time domain representation of Lightning First Stroke
Severe Lightning Strike, defined in terms of lightning current
EMC for LARGE installations
0 2 104 4 10
40
1 105
2 105
time [s]
Cur
rent
[A
]
trtq eektLEMP 0)(
0 = 200 [kA]
k = 1.09
q = 11354
r = 647265
Note: the LEMPis a powerful
Low ImpedanceEffect
Rates of change @ 10 [m]
smVt
E//108.6 11
smA
t
H//102.2 9
remember: B = .H
64
EMC Europe 2016, Wroclaw, Poland 127
Frequency Domain graph of Lightning First Stroke
it is clear that most of the lightning energy is in the low frequency area
1 100 1 104 1 10
6 1 108 1 10
100
5
10
15
20
frequency [Hz]
[A/H
z]
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 128
Calculate the Effect of an Indirect Lightning Stroke
using Faraday’s Law
Lig
htn
ing
Cu
rren
t
=
=
2·101
0A/s
=2.2· 109
[A/m/s] @ 10 [m]
H
R=distance to stroke
2
surface: A [m2]
Flux in Loop: ·
Induced Voltage:
·where
V
time domain:
frequency domain:
· ·
I, B or is multiplied by frequency!
EMC for LARGE installations
65
EMC Europe 2016, Wroclaw, Poland 129
Normalized Frequency Domain Graph of Lightning
shows frequencies of maximum impact (voltage induced in small loop)
1 100 1 104 1 10
6 1 108 1 10
10100
50
0
50
Frequency [Hz]
Indu
ced
volta
ge [d
BuV
/Hz]
multiply every amplitude in the graph by its frequency: “Normalization”
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 130
Distribution of Lightning over the World and the Year
NASA movie clip
Sou
rce:
You
Tub
e
EMC for LARGE installations
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High Altitude Nuclear Explosion Initiates E‐field Pulse
The Compton Effect converts Gamma Ray Energy into Electric Field
The Compton Effect
EMC for LARGE installations
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Extra‐Atmospheric Nuclear EMP Blast is Far‐Field
in the far field there is a fixed ratio of Electric and Magnetic Field (Impedance)
= 120· 377Ω 0
Impedance of Vacuum or Air
• This means that if you know one (E or H)
• You can calculate the other!
• EMP is usually specified in terms of E (!)
• If you need H, calculate it.
EMC for LARGE installations
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HEMP Impulse Illuminates Large Areas
Ground Coverage for High‐Altitude Bursts at 100, 300 and 500 km
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 134
The HEMP Phenomenon (movie clip)
Sou
rce
:Y
ouT
ube
Fut
ure
wea
pons
: E
MP
bom
b
EMC for LARGE installations
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Characteristics of the HEMP
time domain representation
0 2 108 4 10
8 6 108 8 10
8 1 107
0
2 104
4 104
6 104
time [s]
Am
plitu
de [
V/m
]
Time domain representation of RS105 pulse
trtq eekEtHEMP 0)(
E0 = 50000 [V/m]
k = 1.3
q = 4 x 107
r = 6 x 108
Note: the HEMPis a relatively
High ImpedanceEffect
(377 )
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 136
Characteristics of the HEMP
frequency domain representation
1 10 100 1 103 1 10
4 1 105 1 10
6 1 107 1 10
8 1 109
0
5 104
1 103
1.5 103
frequency [Hz]
Am
plitu
de [
V/m
/Hz]
HEMP in the frequency domain
EMC for LARGE installations
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Normalizing to find Frequency of Maximum Impact
effective induced voltage in a small loop as function of frequency
1 100 1 104 1 10
6 1 108 1 10
10100
50
0
50
Frequency [Hz]
Indu
ced
volta
ge [
dBuV
/Hz]
Induced voltage spectrum for HEMP
EMC for LARGE installations
EMC Europe 2016, Wroclaw, Poland 138
Estimation of the Effects
Sou
rce:
You
Tub
e
EMC for LARGE installations
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Power Quality: influence of power‐users
EMI related; Compatibility required
Power LinePower Supply -
Mains GeneratorPower User
Conducted Emissions
Conducted Susceptibility
Other users
Various Powerdisturbances
User Load Fluctuations
“Voltage Quality” or “Quality of Supply”
“Current Quality” or “Quality of Consumption”Reference: Bollen, Math H.J. “Understanding Power Quality Problems”, IEEE Press, 2000ISBN 0-7803-4713-7, IEEE Order Number PC5764
EMC for LARGE installations
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Non‐Sinusoidal Currents and Ohm’s Law
the root cause of most power‐quality related problems
Original Mains Voltage
User Mains Voltage
User Load Current
V = I x RLINE
EMC for LARGE installations
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Mains Voltage and Current as Users Like to See It
clean sine wave voltage and resistive load
EMC for LARGE installations
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History: Reactive Loads
result: phase shift, cosine()
re
im
true or real power
rea
ctiv
e p
ow
er
EMC for LARGE installations
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Today: Non‐Linear Loads
most prominent: diodes charging bulk capacitors
Mains Voltage
Mains Current
Legend
EMC for LARGE installations
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Modern Compact Fluorescent Lamp (CFL)
electronic circuit with diode bridge and bulk capacitor
Diode Bridge
Bulk Capacitor Current Waveformon a “Decent” Sine-Shaped
Voltage Waveform
Source: Wikipedia
EMC for LARGE installations
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Problem with Diode Rectifiers: Synchronicity
all conduct simultaneously on mains voltage! distortion adds up
Same Fluorescent Lampin Large Office Buildingwith distorted Voltage
EMC for LARGE installations
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Small Users <75 W Have No PF Requirements
e.g. all LED’s , CFL’s and many laptops are exempt
Wave-Shape in Large Office Building: Multiple Zero Crossings!
Effect….Heavily DistortedVoltage Waveform
Multiple Zero Crossings
This effect iscalled:HarmonicDistortion
EMC for LARGE installations
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Mapping of EMC on Power Quality (User Aspects)
users on the grid are sources and victims, the grid is the coupling path!
initial power budget new office building exceeded almost twofold
• Estimated required power: 3 MW• Initial installation: 4 MVA (4 x 1 MVA)• Installation upgraded to: 7.2 MVA (+ 2 x 1.6
MVA)• Question: are we or are we not saving cost and energy?
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Problem 2: Switcher Frequencies Pollute Environment
low power fast switching requires short risetime IGBT’s and MOSFETs S
ourc
e:Y
ouT
ube
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Problem 3: Power Islands: Overproduction
mains voltage too high at high illumination levels
>253 VAC@ 45 KVAgeneration
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Mechanism of Overvoltage at Sunny Days: Ohm’s Law
farm’s powercable cannot handle 45 KVA in the opposite direction
400V/10kV
2.5 km
R R
∆ 2
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What if all Neighbours Install Solar Panels?
like the little lamp‐currents, many small ones make one big one!
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How to Solve these Conflicts?
supply and demand, storage, who is in control? the Smart Grid!
Traditional: One Way Traffic
Now: Everybody can Supply or Use
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Coffee Break
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The Current Boundary
a provision to split loops (and shut out noise sources)
“Ground 1” “Ground 2”
Icm (noise current)
loop closes through “ground”
“Ground 2”“Ground 1”Icm
loop closes through “ground”
Create one or more “inner-loops”Short
circuit(s)
reduce looparea
check
Unit 1
Unit 2
(Mains cord 1)(Mains cord 2)(I/O cable 1-2)
Situation in practicedetector:AM-radio
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Install current boundaries at natural interfaces
edge of PCB, cabinet wall, basement of a building; one boundary per unit!
Right Wrong
Icm Icm
Drawbacks:
Current follows longpath over equipment
Loop area cannot easilybe minimized
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Examples of current boundaries on equipment
wide conductors and low‐resistance transitions (be careful with paint) !
protect all units with a current boundary!(and check any conductor that passes it)
Short
Wid
e
check DC resistance witha milli- meter: < 1 m!
NoPaint!
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Use Current Boundary to protect existing “pig‐tail”
pig‐tails can be acceptable as long as CM currents are kept away from it
Icm
H-fieldlines
Wide metal plate
(Current Boundary)
EMC glands
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If many Cables are Guided through Shielding Wall..
other options exist
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Roxtec / Brattberg Glands
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Special Gland System: Many Cables Through Wall
all make good electrical contact in wall (< 10 m)
current boundary 3
Wal
l of
Eq
uip
men
t R
oo
m
Roxtec
Brattberg
MonitoringProbe
Analyserw. TrackingGenerator
Amplifier
InjectionProbe
Wa
ll o
f E
qu
ipm
ent
Ro
om
MIL-STD-1310H
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Next: Separate Cableswith Current Boundaries
classify cables into categories
Model
ICM
Category
red = “source” =“Emission”
1. Noisy (E)
green =“sensitive” =“Immunity”
2. Sensitive (I)
blue =“indifferent” =
“Neutral”
3. Indifferent (N)
E
I N
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Model the Real System in CM loops
Both sensitive (analog, various busses) and (polluted) power lines
M3~
Process control system
powerelectronics
relay’s circuitbreakers
pumps,fans, drives
pneumatic/hydraulic
valves
sensorsProduction process / machine
Controlequipment
Power supply 10 kV/400 V
Industrial Environment
I/Omodule
controlequipmentPLC/PC/Ccontrol buscontrol bus
CP
U b
us
machine structure
Source: C.J. Post “EMC of Large Systems” PATO 2007
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1. herken kringN
Steps:
Separating Cables with Current Boundaries
use Neutral conductor to reduce loop area; then insert current boundary
1. recognize loop
E
I2. reduce looparea
N
3. add boundary
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Separating Cables with Current Boundaries
neutral conductor in practical cases: never a “wire”, always a structure part
cm
cross section:twin wires!
Emission Neutral
(CM-) Transfer impedance of combinationof two relatively thin conductors
is too high (radiates fields)(does not work for high frequencies)
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Separating Cables with Current Boundaries
wide metal reduces fields i.e. the transfer‐impedance of the cm‐current loop
cm
advantage:proximity & skin
effects
Emission
Neutral
Wide sheet metal (“cable guide”) is far superiorto the previous situation. The common-mode
transfer impedance is much lower. Skin effect helps.
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Separating Cables (Alternative)
use structure metal parts to “guide” cables and insert current boundaries
N Steps:1. recognize loop
E
I
2. guide cables with metal strips or trays
3. connect current boundaries to strips
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Separating Cables with Current Boundaries
use (Ground‐) Plane to reduce loop area; then insert current boundaries
NSteps:1. recognize loop
E
I
2. cover loop with metal (ground-)plane
3. connect current boundaries to plane
Note: we are actuallyreducing CM-loop areashere, using wide metal “short-circuits”
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“Plane” could be metal mesh
Separating Cables with Current Boundaries
instead of a metal plane a metal mesh could be used
N
E
I
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wavelength is key to mesh size:apertures should be very smallwith respect to ¼ wavelength ()
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Transfer Impedance improvement
mechanism identical to the single wire case
EMC for LARGE installations
source (50)
scope
Cable 1 (source)
Cable 2 (passive)
50
B
50
A ICM (=noise)
(proximity effect)Icm “squeezes”
under cable
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Use available metal to “short‐out” CM‐currents
e.g. a ship’s deck and walls can be used as groundplane(s)
Important: keep cables near metal over their full length!(unless cables have sufficient shielding to go “unprotected”)
UNPROTECTED
PROTECTED
Good contact(< 1 m)
Goodcontact
?!
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Cable distance is important
once a cable guide is used for protection
H
D
Current distribution of cm in cable guide ismeasure of flux density, , coupling into
cable: at source ~L, at victim ~M!
cm
sourcesourceL
cm
victim
victim
sourceM
proximity effect
closer cable“catches” more flux
Source:Johnson, H“High-SpeedDigital Design”1993
2
1
HD
LM source
2
1
1
HDL
Mk
source
COUPLING FACTOR: k
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Two Types of Current Boundaries
Short Circuit for Common‐Mode “Sources”
Enclosure / EMC Cabinet / Shielded Room
Environment Region “0”
Environment Region “1”
1. Connector Plate
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Three Types of Current Boundaries
Short Circuit for Common‐Mode “Sources”
3. CompletelyShielded
EnclosureEnclosure / EMC Cabinet / Shielded Room
Environment Region “1”
1. Connector Plate
Environment Region “0”
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Motor demonstration
After the addition of a metal cable tray
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Motor demonstration
after the addition of a metal cable tray
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Either filter or shield entire cable
when passing through shielding wall
EMC Gland
C L C
EMC Filter
O.K.
O.K.
Not O.K.
cm
E, H fields
E, H fieldsreradiate
1 V/m
10 mA(3 - 5 A = RE limit)
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Shielding Experiment
Shielding a noisy interconnection using a metal tube (wave guide)
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
cm
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Shielding Experiment
Entering a conductor into tube couples out the noise again
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
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Shielding Experiment
Insulating generator case: battery cable now reradiates noise (antenna)
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
cm
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Shielding Experiment
Entering a screened conductor into tube also couples out the noise again
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
grounding wire
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Shielding Experiment
Grounding the shield with the wire does not solve the interference problem!
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
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Shielding Experiment
Cable shield must be grounded directly to the metal shield to stop the noise
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
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Bad “Grounding” habits
it is Inductance, not the milliOhms that count!
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Shielding Experiment
A filter in the inserted wire does not help if only grounded with a wire
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
ModulationDetected
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Shielding Experiment
only when the wide metal filter plate touches, the shielding works
Wire carryingmodulated RF signal Battery
DC cable
Generator
Radio tuned to RFharmonic frequency
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Filter = “Frequency Dependent” Current Boundaries
EMI filter is usually employed as frequency dependent current boundary
L
N
PE
L‘
N’
LINE LOAD
CX CX
CY CYR
ble
ed
L
L
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• Example of intended segregation of power supply
• Alternative in case of shared power supply: power supply filter
Conducted emission via power supply
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Power supply
M1) Earthing of filter and drive
filter FC
Power supply
M
2) Inductive coupling between in- and output of filter
filterFC
Power supply
MOK
FCfilter
Installation of filter
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50
50
50
50
Source: Goedbloed
Filter demo
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Examples of bad installation practice of filters
Inductive coupling between input and output wiring makes the filter ineffective segregate input and output wiring
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Installation of mains RFI and output filters
Source: Danfoss
Installation of shielded motor cable and cable termination details
Source: ABB
Vendor EMC installation requirements
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Large number of switched applications (motors, valves etc.)
No EMC requirements for single component
Disturbing potential is determined by reactive properties of load, cable lengths, switching frequency and supply voltage
Emission standard for switching transients (clicks) not up to date (based on radio interference (CISPR), whereas immunity of digital circuits, field buses etc. is the main issue.
Installations with switched loads (transients)
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Continuous emissions
Transient emission
EN-IEC 61000-6-4: generic emission standard for industrial environment
Emission as per EN-IEC 61000-6-4
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LloadI
E =½LI2 [J] → ½CV2
V C
Typical specification of relay: Maximum Operating Frequency (No-Load Operation): 3000 Operations / HourMechanical Durability 10,000,000 OperationsElectrical Durability 1,000,000 Operations?Ageing of contacts due to repetitive sparking across contact material
before
Measurement of transients after 60.000
switching events
after
Ageing of switching contacts
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DC AC
De-coupling network between solenoid and
connector
Solenoid of pneumatic valve
DC
AC
Contactor
De-coupling network in connector enclosure
De-coupling network
AC applications: Solid state relay (switching at zero-crossing, no stored energy)
Mitigation of switching disturbance
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L
Mechanical relay
U
Switching transients due to dI/dt
Solid state relay
No switching transients due to dI/dt = 0
Mechanical switch versus solid state relay
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Electromagnetic environments
Residential or industrial
But also: Medical/laboratory
Public space
Heavy industry
Shipping/offshore
Railways
etc.
Appropriate EMC specifications of equipment required to fit the EM level!
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HV area
4
Production plant
3
Office
2
5
Interfaces between EM levels
Installation measures
IEC: 1. very sensitive2. sensitive, domestic / office3. disturbing/noisy, industrial4. very disturbing/noisy, heavy industry5. exception disturbance
1Laboratory
Electromagnetic zones in large installations
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ZONE 3 INDUSTRIAL
ENVIRONMENT
ZONE 2PROTECTED
ENVIRONMENT
ZONE 1WELL PROTECTED ENVIRONMENT
(E.G. EQUIPMENT CABINET)
ELECTRICAL EQUIPMENT
AND INSTRUMENTS
BARRIER BUILDING CONSTRUCTION
(E.G. CONCRETE
REINFORCEMENT
BARRIER STEEL
EQUIPMENT
CABINET = EMC MEASURE AT
BARRIER (BONDING OF
ARMOURED CABLES, FILTERING OF NON-ARMOURED CABLES)
► Specify EM levels for equipment in various EM environments► Specify interfaces between EM zones► Similar to LPZ (Lightning Protection Zones) in EN-IEC-62305-3 and -4
manage the implementation of “EMC” into your system
EMC for LARGE installations
F. Leferink, S. Lerose, M. Sauvageot, W. van Etten “The Four Key Elements of EMC Implementation in Large Organizations” EMC Europe, 2002, Sorrento Italy. A. Roc’h, F. Leferink, “An Audit Tool for the Implementation of EMC in Large Companies”, EMC Europe, 2012, Roma Italy.