EMC Directives
For
Variable Speed Drives
Introduction to IEC
The International Electrotechanical
Commission (IEC), founded in 1906, is
the world’s leading organization that
prepares and publishes International
Standards for all electrical, electronic
and0 related technologies.
The IEC is one of three global sister organizations (IEC, ISO, ITU) that develop
International Standards for the world.
A vast range of technologies is covered by IEC from power generation,
transmission and distribution to home appliances and office equipment,
semiconductors, fiber optics, batteries, solar energy, nanotechnology and marine
energy as well as many others.
IEC Standard 61800-3:2007
 IEC 61800-3:2007 specifies requirements for electromagnetic compatibility
(EMC) standard for PDS - Power Drive Systems with AC or DC motors.
 The Power drive system consists of a motor and Complete Drive
Module (CDM). The CDM consists of a Basic Drive Module (BDM) & its
possible extensions such as a feeding section or some auxiliaries. (See
Figure below)
INSTALLATION or part of installation
POWER DRIVE SYSTEM
COMPLETE DRIVE MODULE
System control & sequencing
Basic drive module (BDM)
Control, converter &
protection
Feeding section
Field supply, dynamic braking
Auxiliaries, others…
MOTOR AND SENSORS
DRIVEN EQUIPMENT
Figure: Definition of the installation & its content
 IEC 61800 is specifically meant for variable speed drives & talks of all
matters, limits & testing related to variable speed drives.
 Since it is VFD specific, It takes into account, the problems created by latest
generation VFDs where the IGBT switching time varies from 100 to 200
nano seconds and dV/dt requirements of IGBTs can be greater than 1000
Volt/micro second.
 All issues like conducted and radiated emission, harmonics emission (low
frequency disturbance), commutation notches, voltage fluctuations ,phase
fluctuations, unbalance voltages ,dips and short interruptions, magnetic
and capacitive coupling are dealt with.
 Also covered is the harmonic current emission requirement relative to the
total current of the agreed power at the PCC (Point of common coupling)
which is another standard IEEE -519.
 Also touches upon system EMC: The objective of system EMC analysis
means to assist in the development of design requirements and procedure
to ensure the drive system meet EMC requirements.
 IEC 61800-3 covers all aspects of EMC generation and mitigation technique
specifically related to Power Drive System.
 IEC 61800-3 has two installation environment I.
II.
First environment
Second environment
Public low voltage
network
Industrial low voltage
network
nd
Point of measurement for 2
environment equipment PDS
Point of measurement for
st
conducted emission 1
environment equipment PDS
Equipment
PDS
Figure: Illustration of environment classes
First Environment
 The first environment includes domestic premises.
 It also includes establishments directly connected without intermediate
transformer to a low-voltage power supply network which supplies
buildings used for domestic purposes.
 They are suitable for the EMC environments described by the typical
standards for this type of environment.
Second Environment
 The second environment includes all establishments other than those
directly connected to a low-voltage power supply network which supplies
buildings used for domestic purposes.
EMC EMISSION LIMITS
 The product standard IEC 61800-3 divides PDSs into four categories
according to the intended use.
PDS of category C1
 A PDS (or CDM) with rated voltage less than 1000 V and intended for use in
the first environment
Category C1
 Household appliances
 Usually plug connectable to wall outlet
Example:
TV sets, computers microwave ovens etc.
PDS of category C2
 A PDS (or CDM/BDM) with rated voltage less than 1,000 V, which is neither
a plug in device nor a movable device and is intended to be installed and
commissioned only by a professional.
PDS of category C3

A PDS (or CDM/BDM) with rated voltage less than 1,000 V, intended for
use in the second environment.
PDS of category C4

A PDS (or CDM/BDM) with rated voltage equal to or above 1,000 V, or
rated current equal to or above 400 A, or intended for use in complex
systems in the second environment.
 In applications related to C4 category equipments the EMC plan to meet the
EMC requirement of the intended applications are to be agreed upon where
in the user defines the EMC characteristics of the environment including the
whole installation and the neighborhood. The manufacturer’s liability is to
provide the information on typical emission levels of the PDS which is to be
installed.
Standard EN-55011
 EN 55011 is a product standard for industrial scientific & medical
equipments(ISM) which generate and or use local radio frequency energy
for industrial, scientific, medical or similar purposes excluding applications
in the field of telecommunication and IT.
 It separates all equipment in two groups: Group 1 & Group 2, each group is
further subdivided into two classes Class A & Class B.
Group 1: ISM (industrial scientific & medical equipment) contains all ISM
equipment in which there is intentionally generated and/or used conductively
coupled radio-frequency energy which is necessary for the internal functioning of
the equipment itself.
Group 2: ISM (industrial scientific & medical equipment) equipment contains all
ISM equipment in which radio-frequency energy is intentionally generated and/or
used in the form of electromagnetic radiation for the treatment of material, and
EDM and arc welding equipment.
Class A: Covers devices for usage in all establishments other than domestic and
that are not directly connected to a low voltage power supply network which
supplies domestic environment.
Class B: Covers devices for usage in domestic establishment that are directly
connected to a low power supply network which supplies domestic environment.
Both standards are comparable with reference to limits as shown below.
Table: Comparison of standards