EN 60601-2-7:1998

SLOVENSKI STANDARD
01-september-1998
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Medical electrical equipment - Part 2-7: Particular requirements for the safety of high-
voltage generators of diagnostic X-ray generators (IEC 60601-2-7:1998)
Medizinische elektrische Geräte - Teil 2-7: Besondere Festlegungen für die Sicherheit
von Röntgengeneratoren von diagnostischen Röntgenstrahlenerzeugern (IEC 60601-2-
7:1998)
Appareils électromédicaux - Partie 2-7: Règles particulières de sécurité pour générateurs
radiographiques de groupes radiogènes de diagnostic (IEC 60601-2-7:1998)
Ta slovenski standard je istoveten z: EN 60601-2-7:1998
ICS:
11.040.50 Radiografska oprema Radiographic equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
IEC
STANDARD
60601-2-7
Second edition
1998-02
Medical electrical equipment –
Part 2-7:
Particular requirements for the safety of
high-voltage generators of diagnostic
X-ray generators
Appareils électromédicaux –
Partie 2-7:
Règles particulières de sécurité pour générateurs
radiographiques de groupes radiogènes de diagnostic
 IEC 1998 Droits de reproduction réservés  Copyright - all rights reserved
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procédé, électronique ou mécanique, y compris la photo- including photocopying and microfilm, without permission in
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CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE X
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue

– 2 – 60601-2-7 © IEC:1998 (E)
CONTENTS
Page
FOREWORD .4
SECTION 1: GENERAL
Clause
1 Scope and object . 5
1.1 Scope . 5
1.2 Object. 5
1.3 Particular Standards . 6
2 Terminology and definitions. 7
2.101 Qualifying conditions for defined terms . 8
3 General requirements . 9
5 Classification . 9
6 Identification, marking and documents. 9
6.1 Marking on the outside of EQUIPMENT or EQUIPMENT parts . 9
6.7 Indicator lights and push-buttons. 10
6.8 ACCOMPANYING DOCUMENTS . 11
SECTION 2: ENVIRONMENTAL CONDITIONS
10 Environmental conditions . 13
SECTION 3: PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
15 Limitation of voltage and/or energy. 15
16 ENCLOSURES and PROTECTIVE COVERS . 15
19 Continuous LEAKAGE CURRENTS and PATIENT AUXILIARY CURRENTS . 15
19.3 Allowable values. 15
20 Dielectric strength. 16
20.3 Values of test voltages. 16
20.4 Tests. 17
SECTION 4: PROTECTION AGAINST MECHANICAL HAZARDS
SECTION 5: PROTECTION AGAINST HAZARDS FROM UNWANTED OR
EXCESSIVE RADIATION
29 X-RADIATION. 18
29.1 X-RADIATION generated by diagnostic X-RAY GENERATORS containing
HIGH-VOLTAGE GENERATORS . 18
36 Electromagnetic compatibility. 22

60601-2-7 © IEC:1998 (E) – 3 –
SECTION 6: PROTECTION AGAINST HAZARDS OF IGNITION OF
FLAMMABLE ANAESTHETIC MIXTURES
SECTION 7: PROTECTION AGAINST EXCESSIVE TEMPERATURES AND
OTHER SAFETY HAZARDS
42 Excessive temperatures. 22
SECTION 8: ACCURACY OF OPERATING DATA AND PROTECTION
AGAINST HAZARDOUS OUTPUT
50 Accuracy of operating data. 23
50.1 General. 23
50.101 Indication of electric and RADIATION output. 23
50.102 Reproducibility, linearity and constancy . 24
50.103 Accuracy of LOADING FACTORS. 28
50.104 Test conditions. 28
50.105 Conditions for measuring AIR KERMA . 30
51 Protection against hazardous output . 32
SECTION 9: ABNORMAL OPERATION AND FAULT CONDITIONS;
ENVIRONMENTAL TESTS
SECTION 10: CONSTRUCTIONAL REQUIREMENTS
56 Components and general assembly. 32
56.7 Batteries . 32
57 MAINS PARTS, components and layout. 33
57.10 CREEPAGE DISTANCES and AIR CLEARANCES . 33
Tables
101 Reference values for the APPARENT RESISTANCE OF SUPPLY MAINS . 13
102 Duration of dielectric strength test . 17
103 LOADINGS for testing AUTOMATIC EXPOSURE CONTROLS . 27
104 ATTENUATION for the measurement of AIR KERMA . 31
105 Tests for verifying reproducibility and linearity. 32
CC.1 Recommended LOADING FACTORS for the testing of accuracy . 41
CC.2 Test settings for measurement of AIR KERMA . 42
Figures
AIR KERMA
101 Recommended arrangement for measuring . 34
102 Recommended arrangement for film density testing AUTOMATIC CONTROL SYSTEMS
provided with a TRANSMISSION CHAMBER. 35
Annexes
AA Terminology – Index of defined terms . 36
BB Values of the series R'10 and R'20, ISO 497. 39
CC Choosing LOADING FACTORS for tests . 40

– 4 – 60601-2-7 © IEC:1998 (E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_________
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-7: Particular requirements for the safety of
high-voltage generators of diagnostic X-ray generators
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60601-2-7 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This second edition cancels and replaces the first edition published in 1987, and constitutes a
technical revision. The text of this standard is based on the following documents:
FDIS Report on voting
62B/329/FDIS 62B/334/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
Annexes AA and BB form an integral part of this standard.
Annex CC is for information only.
In this standard, the following print types are used:
– requirements, compliance with which can be tested and definitions: roman type;
– explanations, advice, notes, general statements and exceptions: smaller type;
– test specifications: italic type;
– TERMS DEFINED IN CLAUSE 2 OF THE GENERAL STANDARD OR IN IEC 60788: SMALL CAPITALS.
A bilingual version of this standard may be issued at a later date.

60601-2-7 © IEC:1998 (E) – 5 –
MEDICAL ELECTRICAL EQUIPMENT –
Part 2-7: Particular requirements for the safety of
high-voltage generators of diagnostic X-ray generators
SECTION 1: GENERAL
The clauses and subclauses of this section of the General Standard apply except as follows:
1 Scope and object
This clause of the General Standard applies except as follows:
1.1 Scope
Replacement:
This Particular Standard applies to HIGH-VOLTAGE GENERATORS of medical diagnostic X-RAY
GENERATORS and to their subassemblies including the following:
– HIGH-VOLTAGE GENERATORS that are integrated with an X-RAY TUBE ASSEMBLY;
– HIGH-VOLTAGE GENERATORS of radiotherapy treatment simulators.
Where appropriate, requirements for X-RAY GENERATORS are given but only where these
concern the functioning of the associated HIGH-VOLTAGE GENERATOR.
This standard excludes
– CAPACITOR DISCHARGE HIGH-VOLTAGE GENERATORS (these are covered by IEC 60601-2-15),
– HIGH-VOLTAGE GENERATORS for mammography,
– HIGH-VOLTAGE GENERATORS for RECONSTRUCTIVE TOMOGRAPHY.
1.2 Object
Replacement:
The object of this standard is to establish particular requirements to ensure safety and to
specify methods for demonstrating compliance with those requirements.
NOTE 1 – Requirements for reproducibility, linearity, constancy and accuracy are given because of their
relationship to the quality and quantity of the IONIZING RADIATION produced, and are confined to those considered
necessary for safety.
NOTE 2 – Both the levels for compliance and the tests prescribed to determine compliance reflect the fact that the
safety of HIGH-VOLTAGE GENERATORS is not sensitive to small differences in levels of performance. The combinations
of LOADING FACTORS specified for the tests are, therefore, limited in number but chosen from experience as being
appropriate in most cases. It is considered important to standardize the choice of combinations of LOADING FACTORS
so that comparison can be made between tests performed in different places on different occasions. However,
combinations other than those specified could be of equal technical validity.
NOTE 3 – The safety philosophy on which this standard is based is described in the introduction to the General
Standard and in IEC 60513.
– 6 – 60601-2-7 © IEC:1998 (E)
NOTE 4 – Concerning RADIOLOGICAL PROTECTION it has been assumed in the preparation of this standard
that MANUFACTURERS and USERS do accept the general principles of the ICRP as stated in ICRP 60, 1990,
1)
paragraph 112, namely:
a) "No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the
exposed individuals or to society to offset the radiation detriment it causes. (The justification of a practice.)
b) In relation to any particular source within a practice, the magnitude of individual doses, the number of
people exposed, and the likelihood of incurring exposures where these are not certain to be received should
all be kept as low as reasonably achievable, economic and social factors being taken into account. This
procedure should be constrained by restrictions on the doses to individuals (dose constraints), or the risks to
individuals in the case of potential exposures (risk constraints), so as to limit the inequity likely to result from
the inherent economic and social judgements. (The optimisation of protection.)
c) The exposure of individuals resulting from the combination of all the relevant practices should be subject to
dose limits, or to some control of risk in the case of potential exposures. These are aimed at ensuring that
no individual is exposed to radiation risks that are judged to be unacceptable from these practices in any
normal circumstances. Not all sources are susceptible of control by action at the source and it is necessary
to specify the sources to be included as relevant before selecting a dose limit. (Individual dose and risk
limits)."
NOTE 5 – Most of the requirements on X-RAY EQUIPMENT and its subassemblies for protection against IONIZING
RADIATION are given in the Collateral Standard IEC 60601-1-3.
This standard does, however, deal with some aspects of RADIOLOGICAL PROTECTION, mainly those that depend upon
the supply, control and indication of electrical energy from the HIGH-VOLTAGE GENERATOR.
NOTE 6 – It is recognized that many of the judgements necessary to follow the ICRP general principles have to be
made by the USER and not by the MANUFACTURER of the EQUIPMENT.
1.3 Particular Standards
Addition:
This Particular Standard, hereinafter referred to as "this standard", amends and supplements
a set of IEC publications, hereinafter referred to as "General Standard", consisting of
IEC 60601-1: 1988, Medical electrical equipment – Part 1: General requirements for safety, its
amendments 1 (1991) and 2 (1995), and all Collateral Standards. The numbering of sections,
clauses and subclauses of this standard corresponds to that of the General Standard. The
changes to the text of the General Standard are specified by the use of the following words:
"Replacement" means that the clause or subclause of the General Standard is replaced
completely by the text of this standard.
"Addition" means that the text of this standard is additional to the requirements of the General
Standard.
"Amendment" means that the clause or subclause of the General Standard is amended as
indicated by the text of this standard.
Subclauses or figures which are additional to those of the General Standard are numbered
starting from 101, additional annexes are lettered AA, BB, etc., and additional items aa), bb), etc.
Where there is no corresponding section, clause or subclause in this standard, the section,
clause or subclause of the General Standard applies without modification.
Where it is intended that any part of the General Standard, although possibly relevant, is not to
be applied, a statement to that effect is given in this standard.
A requirement of this standard replacing or modifying requirements of the General Standard
takes precedence over the original requirements concerned.
________
1)
Annals of
ICRP Publication 60: Recommendations of the International Commission on Radiological Protection (
the ICRP Vol. 21 No 1-3, 1990). Published by Pergamon Press.

60601-2-7 © IEC:1998 (E) – 7 –
1.3.101 Related International Standards
This standard requires HIGH-VOLTAGE GENERATORS, or subassemblies thereof, to comply with
the applicable requirements of IEC 60601-1-3.
NOTE – IEC 60601-1-3 contains the following:
"In the following IEC standards, requirements that relate to medical diagnostic X-RAY EQUIPMENT are superseded by
the requirements in this Collateral Standard:
IEC 60407: 1973, Radiation protection in medical X-ray equipment 10 kV to 400 kV
IEC 60407A: 1975, First supplement to IEC 60407 ."
Attention is drawn to the existence of the following IEC publications:
IEC 60417P:1997, Graphical symbols for use on equipment: Index, survey and compilation of
the single sheets – Fifteenth supplement
IEC 60601-2-15:1988, Medical electrical equipment – Part 2: Particular requirements for the
safety of capacitor discharge X-ray generators
IEC 60601-2-28:1993, Medical electrical equipment – Part 2: Particular requirements for the
safety of X-ray source assemblies and X-ray tube assemblies for medical diagnosis
IEC 60601-2-32:1994, Medical electrical equipment – Part 2: Particular requirements for the
safety of associated equipment of X-ray equipment
IEC 60613:1989, Electrical, thermal and loading characteristics of rotating anode X-ray tubes
for medical diagnosis
IEC 60664-1:1992, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60788: 1984,
Medical radiology – Terminology
ISO 497:1973, Guide to the choice of series of preferred numbers and of series containing
more rounded values of preferred numbers
ISO 3665:1976, Photography – Intra-oral dental radiographic film – Specifications
ISO 7000:1989, Graphical symbols for use on equipment – Index and synopsis
2 Terminology and definitions
This clause of the General Standard applies except as follows:
Addition before 2.1:
In this standard, terms printed in SMALL CAPITALS are used in accordance with their definitions
in the General Standard or in IEC 60788.
NOTE – Attention is drawn to the fact that, in cases where the concept addressed is not strongly confined to the
definition given in one of the publications listed above, a corresponding term is printed in lower case letters.
An index of defined terms used in this standard is given in annex AA.
Associated conditions qualifying the usage of certain terms are given in 2.101.
aa) In this standard unless otherwise indicated:
– values of X-RAY TUBE VOLTAGE refer to peak values, transients being disregarded;
– values of X-RAY TUBE CURRENT refer to average values.

– 8 – 60601-2-7 © IEC:1998 (E)
bb) The electric power in the high-voltage circuit mentioned in 6.8.2 a) 3) and 6.8.2 a) 4) is
calculated according to the formula:
P = f U I
where
P  is the electric power;
f  is the factor depending on the waveform of the X-RAY TUBE VOLTAGE, selected as below and is
ONE PEAK HIGH VOLTAGE GENERATORS TWO PEAK HIGH VOLTAGE GENERATORS
a) 0,74 for - - and - - , or
b) 0,95 for SIX-PEAK HIGH-VOLTAGE GENERATORS, or
c) 1,00 for TWELVE-PEAK HIGH-VOLTAGE GENERATORS and CONSTANT POTENTIAL HIGH-VOLTAGE GENERATORS; or
d) for other HIGH-VOLTAGE GENERATORS, the most appropriate value, 0,74, 0,95 or 1,00, chosen according to the
waveform of the X-RAY TUBE VOLTAGE, with a statement of the value selected;
U  is the X-RAY TUBE VOLTAGE;
I  is the X-RAY TUBE CURRENT.
Addition:
2.101  Qualifying conditions for defined terms
2.101.1  Operating conditions for NOMINAL X-RAY TUBE VOLTAGE
NOMINAL X-RAY TUBE VOLTAGE is defined in IEC 60788 (rm-36-03) as the highest permitted
X-RAY TUBE VOLTAGE for specific operating conditions. In this standard, if specific operating
conditions are not stated, it is to be assumed that the value referenced is unconditional and is
thus the highest X-RAY TUBE VOLTAGE permitted for NORMAL USE of the item under
consideration. Such a value cannot be higher, but is sometimes lower, than values permitted
for certain separate subassemblies or parts of the item.
2.101.2  PERCENTAGE RIPPLE in CONSTANT POTENTIAL HIGH-VOLTAGE GENERATORS
Unless otherwise stated, it is to be assumed that for a HIGH-VOLTAGE GENERATOR to be
regarded as a CONSTANT POTENTIAL HIGH-VOLTAGE GENERATOR, the PERCENTAGE RIPPLE of its
output voltage (under the relevant conditions) does not exceed 4.
2.101.3  RADIATION QUANTITY for NOMINAL SHORTEST IRRADIATION TIME
The definition of NOMINAL SHORTEST IRRADIATION TIME refers to a required constancy of a
RADIATION QUANTITY. In this standard the RADIATION QUANTITY concerned is AIR KERMA.
2.101.4  IRRADIATION TIME
Generally the IRRADIATION TIME is measured in terms of LOADING TIME as the time interval
between:
– the instant that the X-RAY TUBE VOLTAGE has risen for the first time to a value of 75 % of the
peak value; and
– the instant at which it finally drops below the same value.
For systems in which LOADING is controlled by electronic switching of the high voltage, using a
grid in an electronic tube or in the X-RAY TUBE, the LOADING TIME may be determined as the time
interval between the instant when the TIMING DEVICE generates the signal to start the
IRRADIATION and the instant when it generates the signal to terminate the IRRADIATION.
For systems in which LOADING is controlled by simultaneous switching in the primaries of both
the high-voltage circuit and the heating supply for the filament of the X-RAY TUBE, the LOADING
time shall be determined as the time interval between the instant when the X-RAY TUBE
CURRENT first rises above 25 % of its maximum value and the instant when it finally falls below
the same value.
60601-2-7 © IEC:1998 (E) – 9 –
3 General requirements
This clause of the General Standard applies except as follows:
3.1  Addition:
HIGH-VOLTAGE GENERATORS shall be designed so as not to deliver in NORMAL USE, to any
connected X-RAY TUBE ASSEMBLY, a voltage greater than the NOMINAL X-RAY TUBE VOLTAGE for
the X-RAY TUBE ASSEMBLY concerned.
5  Classification
This clause of the General Standard applies except as follows:
5.1  Replacement:
HIGH-VOLTAGE GENERATORS shall be CLASS I EQUIPMENT or INTERNALLY POWERED EQUIPMENT.
5.6  Replacement:
HIGH VOLTAGE GENERATORS
Unless otherwise specified, - or subassemblies thereof shall be
classified as suitable for continuous connection to the SUPPLY MAINS in the STAND-BY STATE and
for specified LOADINGS; see also 6.1 m) and 6.8.101.
6  Identification, marking and documents
This clause of the General Standard applies except as follows:
6.1  Marking on the outside of EQUIPMENT or EQUIPMENT parts
g)  Connection to the supply
Addition:
–For HIGH-VOLTAGE GENERATORS that are specified to be permanently installed, the
ACCOMPANYING
information required in 6.1 g) of the General Standard may be stated in the
DOCUMENTS only.
h)  Supply frequency
Addition:
–For HIGH-VOLTAGE GENERATORS that are specified to be permanently installed, the
information required in 6.1 h) of the General Standard may be stated in the ACCOMPANYING
DOCUMENTS only.
j)  Power input
Addition:
HIGH VOLTAGE GENERATORS
For - that are specified to be permanently installed, the information
may be stated in the ACCOMPANYING DOCUMENTS only.
The information on the input power shall be specified in terms of combinations of
1) the RATED MAINS VOLTAGE of the X-RAY GENERATOR in volts; see item g),
2) the number of phases; see item g),
3) the frequency, in hertz; see item h),
4) the maximum permissible value for APPARENT RESISTANCE OF SUPPLY MAINS, in ohms;
5) the characteristics of OVER-CURRENT RELEASES required in the SUPPLY MAINS.

– 10 – 60601-2-7 © IEC:1998 (E)
m) Mode of operation
Replacement:
The mode of operation – where appropriate, together with maximum permissible ratings – shall
be stated in the ACCOMPANYING DOCUMENTS; see 6.8.101.
n) Fuses
Addition:
For HIGH-VOLTAGE GENERATORS that are specified to be permanently installed, this subclause of
the General Standard does not apply; see item j).
p) Output
Replacement:
This subclause of the General Standard does not apply.
t) Cooling conditions
Addition:
The cooling requirements for the safe operation of a HIGH-VOLTAGE GENERATOR, or a sub-
assembly thereof, shall be indicated in the ACCOMPANYING DOCUMENTS, including as
appropriate:
– the maximum heat dissipation into the surrounding air, given separately for each sub-
assembly that dissipates more than 100 W and might be separately located on installation;
– the maximum heat dissipation into forced air cooling devices, and the corresponding flow
rate and temperature rise of the forced air stream;
– the maximum heat dissipation into a cooling medium utility and the permissible input
temperature range, minimum flow rate and pressure requirements for the utility.
Addition:
aa) Marking of compliance
If, for a HIGH-VOLTAGE GENERATOR or subassembly thereof, compliance with this standard is to
be marked on the outside of the EQUIPMENT, such marking shall be made in combination with
MODEL OR TYPE REFERENCE
the as follows:
[MODEL OR TYPE REFERENCE] IEC 60601-2-7
6.7  Indicator lights and push-buttons
a) Colours of indicator lights
Addition after the first paragraph:
For HIGH-VOLTAGE GENERATORS, the colours to be used for indicator lights shall be as follows:
– the colour green shall be used at the CONTROL PANEL to indicate the state from which one
further action leads to the LOADING STATE; see 29.1.102 a);
– the colour yellow shall be used at the CONTROL PANEL to indicate the LOADING STATE; see
29.1.102 b).
NOTE – The colours of indicator lights need to be chosen according to the message to be given. Thus, the same
operational state of an EQUIPMENT can have simultaneous indications in different colours depending upon the place
of indication, for example green at the CONTROL PANEL and red at the entrance to the EXAMINATION ROOM.

60601-2-7 © IEC:1998 (E) – 11 –
6.8  ACCOMPANYING DOCUMENTS
6.8.2  INSTRUCTIONS FOR USE
a) General information
Addition:
Electric output data shall be stated in the INSTRUCTIONS FOR USE in terms of LOADING FACTORS
as described in 6.8.2 a) 1) to 6.8.2 a) 6).
HIGH VOLTAGE GENERATOR
For diagnostic devices in which part of the - is integrated with the
X-RAY TUBE ASSEMBLY (for example X-RAY TUBE HEADS) the stated values shall refer to the
complete device.
The following combinations and data shall be stated:
1) For both CONTINUOUS MODE and INTERMITTENT MODE, the corresponding NOMINAL X-RAY
TUBE VOLTAGE RAY TUBE CURRENT HIGH
together with the highest X- obtainable from the -
VOLTAGE GENERATOR when operated at that X-RAY TUBE VOLTAGE.
2) For both CONTINUOUS MODE and INTERMITTENT MODE, the corresponding highest X-RAY
TUBE CURRENT together with the highest X-RAY TUBE VOLTAGE obtainable from the HIGH-
VOLTAGE GENERATOR when operating at that X-RAY TUBE CURRENT.
3) For both CONTINUOUS MODE and INTERMITTENT MODE, the corresponding combination of
X-RAY TUBE VOLTAGE and X-RAY TUBE CURRENT which results in the highest electric output power.
4) The NOMINAL ELECTRIC POWER given as the highest constant electric output power in
kilowatts which the HIGH-VOLTAGE GENERATOR can deliver, for a LOADING TIME of 0,1 s at an
X-RAY TUBE VOLTAGE of 100 kV or, if these values are not selectable, with an X-RAY TUBE
VOLTAGE nearest to 100 kV and the value of LOADING TIME nearest to but not less than 0,1 s.
The NOMINAL ELECTRIC POWER shall be given together with the combination of X-RAY TUBE
VOLTAGE and X-RAY TUBE CURRENT and the LOADING TIME.
5) For HIGH-VOLTAGE GENERATORS indicating precalculated or measured CURRENT TIME
PRODUCT CURRENT TIME PRODUCT LOADING FACTORS
, the lowest or the combinations of
resulting in the lowest CURRENT TIME PRODUCT.
If the value of the lowest CURRENT TIME PRODUCT depends upon the X-RAY TUBE VOLTAGE or
upon certain combinations of values of LOADING FACTORS, the lowest CURRENT TIME PRODUCT
may be given as a table or curve showing the dependence.
6) For HIGH-VOLTAGE GENERATORS provided with AUTOMATIC EXPOSURE CONTROL SYSTEMS
controlling the IRRADIATION TIME, the NOMINAL SHORTEST IRRADIATION TIME.
If the NOMINAL SHORTEST IRRADIATION TIME depends upon LOADING FACTORS such as X-RAY
TUBE VOLTAGE and X-RAY TUBE CURRENT, the ranges of these LOADING FACTORS for which the
NOMINAL SHORTEST IRRADIATION TIME is valid shall be stated.
For HIGH-VOLTAGE GENERATORS provided with AUTOMATIC EXPOSURE CONTROL SYSTEMS
controlling the X-RAY TUBE VOLTAGE or the X-RAY TUBE CURRENT the maximum possible
excursion of the X-RAY TUBE VOLTAGE or the X-RAY TUBE CURRENT during the IRRADIATION
shall be stated in the INSTRUCTIONS FOR USE.

– 12 – 60601-2-7 © IEC:1998 (E)
6.8.3 Technical description
a) General
Addition:
The technical description shall contain information about the combination or, if necessary, the
combinations of subassemblies and ACCESSORIES of an X-RAY GENERATOR with which
compliance with the requirements of 50.101 and 50.102 can be shown; see 50.1.
NOTE – Attention is drawn to the usefulness in the technical description of
– data and essential characteristics to determine the ratings of an earth leakage circuit breaker, or
– indication of the types of earth leakage circuit breakers which can be used with the HIGH-VOLTAGE
GENERATOR.
Addition:
6.8.101 Reference to ACCOMPANYING DOCUMENTS
Clauses and subclauses of this standard in which additional requirements concerning the
content of ACCOMPANYING DOCUMENTS are given:
Mode of operation and specified LOADINGS . 5.6 and 6.1 m)
Connection to the supply. 6.1 g)
Number of phases of SUPPLY MAINS. 6.1 g) and 6.1 j) 2)
Frequency of SUPPLY MAINS. 6.1 h) and 6.1 j) 3)
Power input . 6.1 j)
MAINS VOLTAGE . 6.1 j) 1)
APPARENT RESISTANCE OF SUPPLY MAINS. 6.1 j) 4) and 10.2.2
OVER-CURRENT RELEASE. 6.1 j) 5)
Fuses . 6.1 n)
Cooling conditions . 6.1 t)
Electric output data, combinations of LOADING FACTORS . 6.8.2 a) and 50.101
Suitable combinations for compliance test. 6.8.3 a) and 50.1
Earth leakage circuit breaker . 6.8.3 a)
Compliance with this standard . 6.8.102
PROTECTIVE EARTH CONDUCTOR
Central connection point . 19.3
Range and interrelation of LOADING FACTORS . 29.1.102 e)
Test conditions for automatic control in INTERMITTENT MODE. 29.1.102 e)
Method to check the AUTOMATIC INTENSITY CONTROL and
AUTOMATIC EXPOSURE CONTROL. 29.1.104 f)
Equal intervals on scales . 29.1.106 e)
Combinations with the HIGH-VOLTAGE GENERATOR . 50.1
Suitable test combinations . 50.1
LOADING FACTORS and modes of operation . 50.101.1 a)
LOADING FACTORS in fixed combinations . 50.101.2 a)
Provisions for semi-permanent values of LOADING FACTORS . 50.101.2 b)
Density correction of AUTOMATIC EXPOSURE CONTROL . 50.102.2 dd) 2)
6.8.102 Statement of compliance
If, for an X-RAY GENERATOR or a HIGH-VOLTAGE GENERATOR, or a subassembly of the latter,
compliance with this standard is to be stated, the statement shall be made in the following form:
MODEL OR TYPE REFERENCE
X-ray generator [ ] IEC 60601-2-7:1998 or
High-voltage generator [MODEL OR TYPE REFERENCE] IEC 60601-2-7:1998 or
[Name of subassembly] [MODEL OR TYPE REFERENCE] IEC 60601-2-7:1998.

60601-2-7 © IEC:1998 (E) – 13 –
SECTION 2: ENVIRONMENTAL CONDITIONS
The clauses and subclauses of this section of the General Standard apply except as follows:
10  Environmental conditions
This clause of the General Standard applies except as follows:
10.2.2 Power supply
Item a)
Addition:
The internal impedance of a SUPPLY MAINS is to be considered sufficiently low for the operation
of a HIGH-VOLTAGE GENERATOR if the value of the APPARENT RESISTANCE OF SUPPLY MAINS does
not exceed
•
the appropriate reference value according to table 101, or
• the value specified according to 6.1 j) 4), whichever is the greater.
Table 101 – Reference values for the APPARENT RESISTANCE OF SUPPLY MAINS
Waveform of NOMINAL MAINS VOLTAGE
NOMINAL
high voltage
ELECTRIC POWER V
according to
480 440 415 400 240 230 208 120
6.8.2 a) 4)
APPARENT RESISTANCE OF SUPPLY MAINS
kW
Ω
One-peak 0,5 0,95 0,81 0,70
1,0 2,4 2,0 1,79 1,66 0,60 0,55 0,45 0,15
2,0 1,6 1,3 1,19 1,10 0,40 0,36 0,30 0,10
4,0 1,0 0,80 0,72 0,66 0,24 0,22 0,18 0,06
8,0 0,50 0,40 0,36 0,33 0,12 0,11 0,09 0,032
10,0 0,40 0,34 0,30 0,27
16,0 0,24 0,20 0,18 0,17
Two-peak 4,0 1,6 1,3 1,19 1,1 0,40 0,36 0,30 0,10
8,0 1,0 0,80 0,72 0,66 0,24 0,22 0,18 0,06
10,0 0,80 0,67 0,60 0,55 0,18 0,18 0,14 0,045
16,0 0,50 0,40 0,36 0,33 0,12 0,11 0,09 0,032
20,0 0,40 0,34 0,30 0,27
32,0 0,24 0,20 0,18 0,17
50,0 0,16 0,14 0,12 0,11
Six-peak, 16,0 0,83 0,65 0,60 0,55 0,19 0,18 0,14 0,045
twelve-peak
20,0 0,64 0,50 0,48 0,44 0,14 0,15 0,11 0,035
and up to
32,0 0,40 0,34 0,30 0,27
constant
potential
40,0 0,32 0,27 0,24 0,22
50,0 0,24 0,20 0,18 0,17
75,0 0,16 0,14 0,12 0,11
100 0,12 0,10 0,09 0,09
150 0,08 0,07 0,06 0,056
– 14 – 60601-2-7 © IEC:1998 (E)
A supply derived from a local electric power generator is considered suitable only if it is
approved as such by the MANUFACTURER of the HIGH-VOLTAGE GENERATOR.
NOTE – If a NOMINAL voltage is claimed for a mains power supply system, it is assumed that there is no voltage of a
higher value between any of the conductors of the system, or between any of these conductors and earth.
An alternating voltage is considered in practice to be sinusoidal if any instantaneous value of the waveform
concerned differs from the instantaneous value of the ideal waveform at the same moment by no more than ±2 % of
the peak value of the ideal waveform.
A three-phase SUPPLY MAINS is considered to have a practical symmetry if it delivers symmetrical voltages and
produces, when loaded symmetrically, symmetrical currents.
Symmetrical voltages are considered to exist, if, when determined according to Fortescue's
2)
theorem , neither the magnitude of the negative sequence voltages nor the magnitude of the
zero sequence voltages exceeds 2 % of the magnitude of the positive sequence voltages.
Symmetrical currents are considered to exist if, when determined according to Fortescue's
2)
theorem , neither the magnitude of the negative sequence currents, nor the magnitude of the
zero sequence currents exceeds 5 % of the magnitude of the positive sequence currents.
NOTE – The requirements of this standard are based upon the assumption that three-phase systems have a
symmetrical configuration of the MAINS VOLTAGE with respect to earth and include a neutral conductor, and that
single-phase systems are derived from such three-phase systems. Where the supply system is not earthed at the
source it is assumed that adequate measures have been provided to detect, limit and remedy any disturbance of
symmetry within a reasonably short time.
A HIGH-VOLTAGE GENERATOR is considered to comply with the requirements of this standard only if its specified
NOMINAL ELECTRIC POWER can be demonstrated at an APPARENT RESISTANCE OF SUPPLY MAINS having a value not less
than the relevant reference value in table 101 or not less than the APPARENT RESISTANCE OF SUPPLY MAINS specified
according to 6.1 j) 4), whichever is the greater.
For this purpose, the APPARENT RESISTANCE OF SUPPLY MAINS R is determined according to the formula:
-
U U
R =
I1
where
U is the no-load MAINS VOLTAGE;
o
U is the MAINS VOLTAGE under load;
I is the mains current under load.
The MAINS VOLTAGE shall be measured between
– phase and neutral in a single-phase system,
– phase and phase in a two-phase system,
– each two phases in a three-phase system.
The APPARENT RESISTANCE OF SUPPLY MAINS shall be measured by applying a single resistive
load of a value corresponding approximately to the NOMINAL ELECTRIC POWER specified
according to 6.8.2 a) 4), but not more than 30 kW.
Reference values for the APPARENT RESISTANCE OF SUPPLY MAINS for NOMINAL MAINS VOLTAGES
not included in table 101 may be interpolated or extrapolated, and shall be calculated on the
basis that the reference value is proportional to the square of the NOMINAL MAINS VOLTAGE.
If values of NOMINAL ELECTRIC POWER between those given in table 101 are specified, it shall be
possible to fulfil all requirements applying for the next lower value of NOMINAL ELECTRIC POWER
given in table 101 with the APPARENT RESISTANCE OF SUPPLY MAINS given for that lower value.
________
2)
C. L. Fortescue, Method of symmetrical co-ordinates applied to the solution of polyphase networks, Trans.
AIEE. vol. 37, pp. 1027 - 1140, 1918.

60601-2-7 © IEC:1998 (E) – 15 –
SECTION 3: PROTECTION AGAINST ELECTRIC SHOCK HAZARDS
The clauses and subclauses of this section of the General Standard apply except as follows:
15 Limitation of voltage and/or energy
This clause of the General Standard applies except as follows:
Addition:
aa) Detachable HIGH-VOLTAGE CABLE CONNECTIONS shall either be designed so that the use of
TOOLS is required to disconnect them or they shall be provided with INTERLOCKS so that at all
times when PROTECTIVE COVERS or high-voltage connections are removed
– the HIGH-VOLTAGE GENERATOR is disconnected from its power supply, and
– capacitances in the high-voltage circuit are discharged within the minimum time necessary
to gain access to the high-voltage circuit, and
– the discharged state is maintained.
Compliance is checked by inspection and by measurement.
bb) Provision shall be made to prevent the appearance of an unacceptably high voltage in the
MAINS PART or in any other low-voltage circuit.
NOTE – This may be achieved for example
PROTECTIVE EARTH TERMINAL
– by provision of a winding layer or a conductive screen connected to the
between high-voltage and low-voltage circuits,
– by provision of a voltage limiting device across terminals to which external devices are connected and
between which an excessive voltage might arise if the external path becomes discontinuous.
Compliance is checked by inspection of design data and construction.
16  ENCLOSURES and PROTECTIVE COVERS
This clause of the General Standard applies except as follows:
Addition:
NOTE – Requirements concerning the resistance and earthing of a flexible conductive screen of high-voltage cables
connected to X-RAY TUBE ASSEMBLIES are given in IEC 60601-2-28.
19  Continuous LEAKAGE CURRENTS and PATIENT AUXILIARY CURRENTS
This clause of the General Standard applies except as follows:
19.3  Allowable values
Addition:
For HIGH-VOLTAGE GENERATORS and subassemblies thereof the column on Type B and the rows
on EARTH LEAKAGE CURRENT, in NORMAL CONDITION and SINGLE FAULT CONDITION and on
ENCLOSURE LEAKAGE CURRENT, in NORMAL CONDITION, of table IV including the notes of the
General Standard apply.
– 16 – 60601-2-7 © IEC:1998 (E)
The allowable values of EARTH LEAKAGE CURRENT are permitted for each subassembly of an
X-RAY EQUIPMENT that is supplied by its own exclusive connection to the SUPPLY MAINS or to a
central connection point, if the latter is fixed and permanently installed.
A fixed and permanently installed central connection point may be provided inside the outer
ENCLOSURE or cover of the HIGH-VOLTAGE GENERATOR. If other subassemblies such as an X-RAY
SOURCE ASSEMBLY or ASSOCIATED EQUIPMENT are connected to the central connection point, the
EARTH LEAKAGE CURRENT between such a central connection point and the external protective
system may exceed the allowable values for any one of the single devices connected.
NOTE – The limitation of the EARTH LEAKAGE CURRENTS within the environment of an X-RAY EQUIPMENT is intended to
ACCESSIBLE PARTS
ensure that do not become live and to prevent interference in other electrical equipment.
The provision of a central connection point is acceptable, as for fixed and perm
...