IEC 6060 1- 1-2,2001:New EMC requirements for
Medical Equipment
Sanjay Baisakhiya,
R.Ganeasn,
Sisir K.Das
SAMEER - Centre for Electromagnetics
Znd Cross, ClT Campus, Taramani, Chennai - 600 113, India
Phone: 044- 22541817,22541424 Fax: 044 - 22541424
e-mail: sameercem@vsnl.com
ABSTRACT-International Eleclrotechnical Commission
(IEC) brought out comprehensive standard IEC 60601-12 , 1 9 9 3 ~ Iediiion) to d r e s s EMC problems in Medical
Equipmenl. Technological developments in medical equipment
and changes in Electromagnetic environment rendered jirst
edition inadequate in d r e s s i n g all issues concerning to
Electromagnetic
CompatibiliryfEMC).lEC
60601-12,2Wl(second edition) was brought out to oddress several of
such issues, which were not the part of first edilian. This paper
intends to analysis two issues
Firstly major changes from first edition and reasons for these
changes. This will helps in befferunderstanding of requirements
of second edilion.
Secondly redesigning products f m EMC perspective to achieve
complinnce to new standard
I. INTRODUCTION
In modem days, medical electricaVelectronics
equipments are widely used by medical professionals
to diagnosis & monitor the patients and administer
treatment to them. Electrocardiogram (ECG),
Ultrasound scanner, pulse oximeter, infant incubator,
X-ray machines are some of the example used for
these purposes. Any malfunction or erroneous
performance of these equipment may lead to wrong
diagnosis and could even endanger the life of patient.
Due to criticality of their operation, several standards
making organization have brought out guidelines and
regulations to achieve EMC in health care area.
Federal Communication Commission (FCC), Center
for Devices and Radiological Health (CDRH) of Food
and Drug Administration (FDA), International
Electrotechnical
Commission
(IEC),
Committee European Electrotechnique (CENELEC)
are few important organizations, who promogulated
standards / regulations in their respective countries.
IEC has mandate of many countries to prepare and
publish intemational standards in electrical and
electronics field. First edition of IEC 60601-1-2 was
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published in April 1993.0flate. it was realized that
though equipment tested for IEC 60601-1-2.1993
standard, still sometimes it may exhibit malfunction
during their use. Authors came across one such case,
where ultrasound scanner, which is used to scan soft
tissues was malfunctioning, inspite of being tested for
the old standard. It was found that conducted emission
from PC, which was used to register patient name,
was interfering with ultrasound scanner. Onset of
wireless communication revolution has added another
dimension to electromagnetic environment faced by
medical equipment. In this paper issues concerning
the changes in the standard and redesigning of
products &e address.
11. IEC 60601 STANDARD
The Intemational Electrotechnical Commission
(IEC) is a worldwide organization for standardization
comprising all national electrotechnical committee.
IEC publishes the international standard. The work of
preparation of standard is entrusted to technical
committee. Standards prepared by this committee are
in the form of recommendation for the intemational
use.
. .
IEC 60601-series is product standard for medical
electrical equipment and its scope is the safety and
essential performance of them. This standard is
grouped in two parts, those numbered “-1-X are
considered relevant to general requirement for safety
and are labeled collateral standard. Those numbered “2-X’ contain requirement for specific kind of medical
equipment. IEC 60601-1-2 is “Medical electronics
equipment-part
1-2:general
requirement . for
safety,collateral standard-EMC requirement and test.
The IEC 60601-2-X standard known as particular or
part. two standard are product standard> e.g. IEC.
60601-2-25, particular ‘requirement for safety of
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409
electrocardiograph. They supplement and in some
cases substitute for requirement of product family
standard.
and IEC 60601-1-4 standards. For immunity failure
criteria is defined very elaborately. Failure criterions
are given in clause 36.202.13 of the standard.
Ill. SALIENTFEATURES OF IEC 60601-1-2,1993, FIRST
Second edition envisages that achieving EMC in
medical equipmenthystem is shared responsibility.
Manufacturer is required to test equipmendsystem as
given in the standard, also it is expected from
manufacturer to inform end user for the type of
environment
equipmenthystem
is
designed.
Manufacturers is also expected to guide end user to
suggest the ways to achieve EM environment for
which equipment is designed. It is responsibility of
end user to follow guidelines provided by
manufacturer to achieve intended EM environment.
EDITION
This standard is based on the standard prepared by
IEC technical committees SC62 A, TC 65 (Industrial
process
measurement
and
control),
TC
77(Electromagnetic compatibility including network)
and CISPR (International special committee on radio
interference). This standard specifies general
requirement
and
test
for
Electromagnetic
Compatibility of medical equipment and/or system.
Radiated emission test, conducted emission test, ESD,
Radiated immunity test, Electrical Fast Transient and
Surge immunity test are included.
IV.NEED FOR CHANGES IN FIRST EDITION
Biggest change that has taken place since
publication of the first edition is the wide spread use
of wireless communication in health care Facilities.
Cellular phones are omnipresent and hospitals are no
exception. Wireless technology is also being used to
transmit and store data related to patient. Use of
wireless technology has brought potential source of
interference i.e. transmitter close to the sensitive
medical electricallelectronics equipment. It became
necessary for these equipment to withstand RF field
from wireless transmitter.
Apart from these changes, many standard, which
were in draft form have been published and are
available now. So these standards are included in the
second edition.
Also, as a matter of policy IEC reviews its standard
at certain interval or before. This exercise is required
to take note of all changes, which have taken place in
course of time. After review IEC issues revised
standard.
V. IEC 60601-1-2,2001 SECOND EDITION
IEC 60601-1-2,2001 i.e. second edition is
completely revised standard. Many new requirements
have heen included. For emission, equipments are to
be properly categorize depending on their intended
use. Second edition requires manufacturer to establish
minimum performance of the equipment, which shall
be ensured during immunity test. This minimum
performance is to be established by doing risk
analysis. Risk analysis may be done using I S 0 14971
410
Higher immunity levels have been prescribed in
second edition for life supporting equipment to
achieve better safety margins. However lower
immunity levels are acceptable like first edition for
certain
equipmenthystems
provided
proper
justifications are given in accompanying document.
VI. COMPARISON O F EMISSION REQUIREMENTS
Table-1 gives comparison of important requirement in
the first and second edition of IEC 60601-1-2
TABLE - I
Emission Requirements - IEC 60601-1-2:1993 & 2001
Emission
requirements
Referred
Standard
for
high frequency
tmissions
(0.15-loo0
IEC 60601-1- 2.
1993
1 IEC 60601-1-2.
2001
CISPR 14
CISPR 14
CISPR 15
CISPR 22
Referred
Standard
for
low frequency
emission
No requirement
Relaxation
limits
Relaxation in field
strength
limits
(RE),if equipment
I system installed
in
shielded
locatio",
relaxation has to
be justified
in
accompanying
document
IEC 6 l W 3 - 2 for
harmonics
IEC 6 1 W 3 - 3 for
voltage fluctuation
and flicker
Relaxation in RE
limit, if equipment I
systems installed in
shielded location by
an amount upto
applicable specified
value of minimum
shielding
effectiveness
MHI)
in
Relaxation
in
conducted emission
limit by an amount
upto
applicable
specified value of
minimum R€ filter
altC""2.tiO"
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2003
First edition requires equipment or system to be tested
as per CISPRII, and for medical radiological
equipments/systems are to be tested for click as per
the provision of CISPR 14.
Second edition requires classification of medical
equipmentkystem in appropriate category and it gives
guidelines by way of flowchart and tables. These
flowchart and guideline tables helps in identifying
appropriate applicable standard to them.
In second edition ,Equipment or systems are to be
tested as per CISPR14,if they do not contain any
electronic circuit. Dental drills used by dentist is one
typical example to be tested as per CISPR14.Lighting
equipment used in medical arena are to be tested as
per CISPR 15.Lightning equipment used for
illuminating X-ray films and in operation theatre are
typical example of medical equipment to qualify for
CISPR 15.Information Technology equipment used
with medical equipment are to be tested for CISPR 22
standard. All other medical equipmenthystems are to
be tested as per CISPR 11.They are to be classified in
group1 or group2 and class A or class B depending on
their intended use.
Second edition requires all electricaUelectronics
equipment which are to be connected to low voltage
public network and draws current less than 16A to be
tested for harmonics emission and voltage variation
and flicker test.
VII. COMPARISON OF IMMUNITY REQUIREMENTS
Comparison of first and second edition immunity
requirements are given in Table-2.Conducted
disturbance test, voltage dips and interruption, power
frequency magnetic field are the new test added in the
second edition, which were not the part of fxst
edition. First edition referred IEC 801 series for
immunity test, many of them were in draft form at the
time of publication of its publication.
According to compliance criteria given in the fxst
edition equipment must continue to perform as per
specifications of the equipment given by manufacturer
and if it fails, it must remain safe, whereas the
compliance criteria is more elaborate in the second
edition. This requires that all those specifications /
functions, which are critical in patients's diagnosis /
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treatment, are to be identified after risk analysis.
These specifications /function must not change or
deteriorate as given in clause. Risk analysis is not
required, if all specificatiodfunctions are monitored
for above degradation during the test.
.
VIII ACCOMPANYING DOCUMENTS
IEC 60601-1-2 has stated objective to achieve
electromagnetic compatibility by coordinated effort
among
manufacturer
,customer
and
users.
Requirement of accompanying documents is a way to
implement this objective.
In first edition, clause 6.8.201 gives the information
required to be supplied to customer/users, if
applicable, by mentioning them in accompanying
document. For equipments using RF energy for its
operation, it is required to give guidelines for
identifying , avoiding and resolving EM1 caused by
this RF energy. All those medical equipments, which
are sensitive for the purpose of their operation ,it is
required to give appropriate guidelines to ensure their
proper operation. Accompanying document must
include justification, if different immunity level other
than specified in the standard are used.
Accompanying documents requirements in second
edition are very elaborate compared to first edition.
More areas are identified ,which affect EMC of
medical equipment during their use. Information
relevant to these area is required to be mentioned in
accompanying document. Some of the important
requirement of accompanying documents in second
edition are as follows.
(a) For all medical equipments, it should cany
statement that portable and mobile RF equipment
can affect medical equipment.
(b) If any connector of medical equipment is
exempted from ESD testing, then ESD warning
symbol is to be put on medical equipment. In
case these ESD sensitive connectors are to be
touched, necessary ESD precautions are to be
given in accompanying documents. All users of
such medical equipment must be informed of this
ESD warning symbol and precautions to be
observed in handling such equipments.
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411
Details of accessories used during the testing and
warning that if accessories other than mentioned
in this report are used. It may affect emission and
immunity levels of the equipment.
If any lower or higher immunity levels than
specified in the standard are
used,proper
justification shall be given.
Guidelines have to be given to achieve
electromagnetic environment, for which medical
equipment is designed.
Radiated RF Electromagnetic Field:
In second edition, the upper frequency. range for this
test is extended from lGHz to 2.5 GHz.This may
require following, changes, if medical equipmend
system has metallic enclosure.
(a) Size of openings in the metallic'enclosure may be
required to reduce to offer shielding at higher
frequency.
(b) Gasket may be required to prevent field leaking
Guidelines on recommended distance between
portable and mobile RF communication
equipment and medical equipment
VIII. ADDITIONAL DESIGN REQUIREMENTS:
through the seam at high frequency.
For life support equipment field strength requirement
is changed from 3V/m to 10 V/m, this may require
additional shielding to achieve compliance to new
requirement.
Emission:
Conductdd RF Immunity Test:
Harmonics emission is a new requirement in second
edition. Though this requirement is normally met by
low power medical equipmendsystem but for high
power medical equipment /system this may he little
tough to qualify. This requirement may necessitate use
of filter and change in power supply circuit for
compliance.
Immunity.
Electrostatic Discharge:
In second edition the contact discharge level is
increased to +I- 6KV from +/- 3KV specified in
previous edition. Increased contact discharge may
require thicker insulation on push buttons, touch
screen to prevent contact discharge. Increased contact
discharge level will also result in higher level of
radiation during indirect discharge. This may require
steps to reduce the radiated coupling to equipment.
For grounded enclosure to maintain same level of
ESD protection from secondary arc discharge due to
increased contact level may require increase in
creepage distance. It may also require to increase the
distance of electronics component kept close to
opening of the enclosure to prevent exposure of them
to intense electric field created when current flows
during contact discharge
412
This is new requirement in second edition. In this test
coupling is predominantly through conducting cables
connected to EUT i.e. main supply, signal line or earth
connection.
Mostly analog circuits are the victims of this type of
interference and those operating at lower signal level
are more prone. Though medical equipment operates
at low frequency but they are susceptible to high level
of W energy due to failure mode audio rectification.
ECG and EEG patient connecting cables are to be
treated specially as these cables are connected to
analog circuit for further processing and very poor
decoupling of signal lines is done to keep low leakage
current. Following techniques may be used with
external cables connected to medical equipment to
harden them against this interference.
(a) Use of shielded cable and properly terminating
them.
(b) Filter the cable, whenever possible.
(cj Use of common mode choke on external cable
Surge:
In second dition,lower voltage levels are also
defined, while in first edition only higher levels were
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defined. Hence suppression should be taken care at
lower level also, if equipment has to comply to second
edition..
Voltage Dips and interruption:
This is a new requirement in second edition.
Following changes may be useful in complying to this
requirement.
(a) Medical equipmenthystems using bridge rectifier
in their power supply may require bigger value
capacitor on its DC bus.
(b) Medical equipmentlsystem using AC main may
require backup supply l i e U P S or batteries to tide
over these dips and interruption on power lines.
Power Frequency Magnetic Field
This is new requirement and it is relevant for medical
equipment using CRT display or Hall effect sensors.
Proper magnetic shielding of them may be useful in
achieving compliance to this requirement.
X. CONCLUSION
.
Second edition of IEC 60601-1-2 is a completely
revised standard. Which is substantially different from
first edition on many aspect. This paper illustrate the
major difference between the two .Efforts is made to
highlight the area in equipment design, which will
need attention to ensure smooth transition to second
edition.
REFERENCES:
(i) IEC 60601-1-2,1993:Medical electrical equipment,
Collateral Standard Electromagnetic Compatibility
requirement and test
(ii)IEC 60601-1-2,2001:Second Edition, Medical
electrical
equipment,
collateral
standard,
Electromagnetic Compatibility: Requirement and
test
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41 3
Table -2
Immunity Requirements - IEC 60601-1-2:1993 Br 2001
Immunity requirements
Elechostatic Discharge
Radiated radio frequency
elechomagnetic field test
IEC 60601-1-2, 2001
IEC 60601-1- 2,1993
EC 801-2
:antact:+/- 3KV
k + I - 8KV
EC 801-3
?eq:26-1 000MHz
%Id
strength:lVlm
(for
shielded
ocations), 3VIm for other locations
EC 610004-2
:ontact:+/-2KV,+/-4KV,+/-SKV
4ir:+I?;KV,+l4KV.+I-6KV
E C 61000-4-3
'req:80-2500 MHz
'ield
strength:3
V/m(for
non-life
supporting
:quipmentlsystem).lOV/m(for life supporting equipment)
?or shielded locations the levels are to be reduced prapodonal to
ihielding effectiveness of the
Locations
Wodulation frequency
.
. :2 Hz(lntended use is to control or meaure
I physiological parameter and operating frequency is 4 Hz or 5
3HZ
Electrical Fast Transient
EC 8014
IKV-Plug connected equipment
!KV-Permanently
installed
:quipmenVsystem
1.5 kV for interconnecting lines lanrer than
E C 610004-4
+I-2 KV AC/DC lines
+I-IKV Signal and interconnecting cable for length>3m
)m
Surge
Conducted
Disturbance,
Induced by RF field
EC 801.5
IKV-differenud made
1KV-Common made
br power line only
E C 61000-4-5
Vo requirement
IEC 61000-4-6
+I-0.5KV.+/-IKV and +/- 2KV for ac power line(s) to ground
+I-OSKV,+/- IKV for ac power line(s) to line(s)
Frequency: I50 KHr-80 MHz (For most of the life suppolting
equipment), 3 V m . Freq:I50 KHz-80 MHz (for most of life
supporting equipment.
3Vms for frequency band other than ISM
lOVms for ISM frequency band
dwell time = min 3sec for equipmentlsystems tested with 2HZ and
lsec for all other erruioment
Voltage Dips and voltage
variation on power supply
input lines
No Reauirement
60% for 5 period
30% for 25 period
295 for 5 sec
(For equipment with rated input power of IKVA or less and all
life supporting equipment)
For not life supporting equipment and for which rated input power
is greater than IKVMrated current is less than I6Mphase
deviation from 36.202.2 j is allowed provided the equipment
remain safe experience no component failure and is restorable to
pre-test state with operator intervention.
For life supporting
are
..
. equipment >16Mphase equipment
.~
exempted from testing
IEC 610004-8
Power frequency.3AJm
~~
Power Frequency magnetic
Field
41 4
No requirement
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