SIST EN 61180-1:1998
(Main)High-voltage test techniques for low-voltage equipment -- Part 1: Definitions, test and procedure requirements
High-voltage test techniques for low-voltage equipment -- Part 1: Definitions, test and procedure requirements
Applies to: -dielectric tests with direct voltage -dielectric tests with alternating voltage -dielectric tests with impulse voltage -tests with impulse current -tests with combinations of the above.
Hochspannungs-Prüftechnik für Niederspannungsgeräte -- Teil 1: Begriffe, Prüfung und Prüfbedingungen
Techniques des essais à haute tension pour matériels à basse tension -- Partie 1: Définitions, prescriptions et modalités relatives aux essais
S'applique aux: - essais diélectriques en tension continue - essais diélectriques en tension alternative - essais diélectriques en tension de choc - essais en courant de choc - essais combinant les essais ci-dessus.
High-voltage test techniques for low-voltage equipment - Part 1: Definitions, test and procedure requirements (IEC 61180-1:1992)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61180-1:1998
01-januar-1998
High-voltage test techniques for low-voltage equipment - Part 1: Definitions, test
and procedure requirements (IEC 61180-1:1992)
High-voltage test techniques for low-voltage equipment -- Part 1: Definitions, test and
procedure requirements
Hochspannungs-Prüftechnik für Niederspannungsgeräte -- Teil 1: Begriffe, Prüfung und
Prüfbedingungen
Techniques des essais à haute tension pour matériels à basse tension -- Partie 1:
Définitions, prescriptions et modalités relatives aux essais
Ta slovenski standard je istoveten z: EN 61180-1:1994
ICS:
19.080 (OHNWULþQRLQHOHNWURQVNR Electrical and electronic
SUHVNXãDQMH testing
SIST EN 61180-1:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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CEI
NORME
IEC
INTERNATIONALE
1180-1
INTERNATIONAL
Première édition
STANDARD First edition
1992-10
essais à haute tension
Techniques des
à basse tension
pour matériels
Partie 1:
Définitions, prescriptions et modalités
relatives aux essais
High-voltage test techniques
for low-voltage equipment
Part 1:
procedure requirements
Definitions, test and
reserved
roduction réservés— Copyright — all rights
© CEI 1992 Droits de rep
No part of this publication may be reproduced or utl¢ed in
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utilisée sous quelque forme que oe soit et par aucun pro-
including photocopying and microfilm, without permission
cédé, électronique ou mécanique, y compris la photocopie et
in writing from the publisher.
les microfilms, sans raccord écrit de réditeur.
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• •
For price, see current catalogue
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1180-1 ©IEC – 3 –
CONTENTS
Page
FOREWORD 9
11
INTRODUCTION
Clause
SECTION 1: GENERAL
13
1.1 Scope
13 1.2 Normative references
SECTION 2: DEFINITIONS
15 2.1 Impulse techniques and insulation
15
2.1.1 Impulse
15
2.1.2 Partial breakdown
Clearance [IEV 441-17-31] 15
2.1.3
15
2.1.4 Creepage distance [IEV 151-03-37]
15 2.1.5 Solid insulation
15
2.2 Characteristics related to disruptive discharge and test voltages
15
2.2.1 Disruptive discharge
17
2.2.2 Characteristics of the test voltage
17
Disruptive discharge voltage 2.2.3
17
2.2.4 Withstand voltage
17
2.2.5 Assured disruptive discharge voltage
SECTION 3: GENERAL REQUIREMENTS RELATING TO TEST PROCEDURES
AND TEST OBJECTS
19 General requirements for test procedures 3.1
19 General arrangement of the test object 3.2
19
3.3 Atmospheric conditions
Standard reference atmosphere 19
3.3.1
19
3.3.2 Atmospheric correction factor
SECTION 4: TESTS WITH DIRECT VOLTAGE
21
Definitions for direct voltage tests 4.1
21
4.1.1 Value of the test voltage
23
4.1.2 Ripple
4.2 Test voltage 23
23
4.2.1 Requirements for the test voltage
4.2.2 Generation and measurement of the test voltage 23
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1180-1 ©I EC – 5 –
Clause Page
23
4.3 Test procedures
23
4.3.1 Withstand voltage tests
4.3.2 Assured disruptive discharge voltage tests 25
SECTION 5: TESTS WITH ALTERNATING VOLTAGE
25 5.1 Definitions for alternating voltage tests
25
5.1.1 Peak value
25
5.1.2 R.M.S value
25
5.2 Test voltage
25 5.2.1 Requirements for the test voltage
27
5.2.2 Generation and measurement of the test voltage
27
5.2.3 Measurement of the test voltage
27
5.3 Test procedures
27
5.3.1 Withstand voltage tests
29
5.3.2 Assured disruptive discharge voltage tests
SECTION 6: TESTS WITH IMPULSE VOLTAGE
6.1 Definitions for impulse tests 29
29
Definitions of general applicability 6.1.1
31
6.2 Test voltage
6.2.1 Standard impulse 31
31 6.2.2 Tolerances on standard impulse
31 6.2.3 Generation of the test voltage
33
6.2.4 Measurement of the test voltage and impulse voltage waveshape
33
6.3 Test procedures
33
Calibration of impulse voltage waveshape 6.3.1
33 6.3.2 Withstand voltage tests
33
6.3.3 Assured disruptive discharge voltage tests
SECTION 7: TESTS WITH IMPULSE CURRENT
35
7.1 Definitions for impulse current tests
35
7.1.1 Impulse current
35
7.1.2 Value of the test current
35
7.1.3 Virtual front time T1
35
7.1.4 Virtual origin 0 1
35
7.1.5 Time to half-value T2
Td 35
7.1.6 Duration of peak of a rectangular impulse current
t 35
7.1.7 Total duration of a rectangular impulse current T
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1180-1 ©IEC - 7 -
Page
Clause
7.2 Test current 37
37
7.2.1 Standard impulse currents
7.2.2 Tolerances 37
37
7.2.3 Measurement of the test current
39
7.2.4 Measurement of voltages during tests with impulse current
7.3 Test procedures 39
SECTION 8: COMPOSITE TESTS
39 Definitions for composite tests 8.1
39
8.1.1 General
8.1.2 Definitions 41
41
8.2 Tests with hybrid impulse generators
8.2.1 Introduction 41
41
8.2.2 Test voltages and currents
43
8.2.3 Generation of test voltage and current
43
8.2.4 Verification of hybrid impulse generator characteristics
45
8.2.5 Measurement of test voltage and current
45
8.3 Test procedures with the hybrid impulse generator alone
45
8.3.1 Preparation of equipment
45
8.3.2 Impulse test sequence
45
8.3.3 Assessment of test results
Test procedures with the hybrid impulse generator and mains 45
8.4
45
8.4.1 General
47
8.4.2 Preparation of equipment
47
8.4.3 Impulse test sequence
47
8.4.4 Assessment of test results
Test procedure with the conventional 1,2/50 impulse generator and mains 47
8.5
50
Figures
Annexes
Arrangements for composite tests (clauses 8.4 or 8.5) 55
A
59
B Information to be given in the test report
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1180-1©IEC
INTERNATIONAL ELECTROTECHNICAL COMMISSION
VOLTAGE TEST TECHNIQUES
HIGH-
FOR LOW-VOLTAGE EQUIPMENT
Part 1: Definitions, test and procedure requirements
FOREWORD
The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
1)
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
They have the form of recommendations for international use and they are accepted by the National
2)
Committees in that sense.
3) In order to promote international unification, the IEC expresses the wish that all National Committees
should adopt the text of the IEC recommendation for their national rules in so far as national conditions will
permit. Any divergence between the IEC recommendation and the corresponding national rules should, as
far as possible, be clearly indicated in the latter.
This standard has been prepared by technical committee 42: High-voltage testing
techniques.
The text of this standard is based on the following documents:
Six Months' Rule Report on Voting
42(CO)51
42(CO)49
Full information on the voting for the approval of this standard can be found in the Voting
Report indicated in the above table.
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1180-1 © I EC –11 –
INTRODUCTION
This International Standard has been prepared in accordance with the decision taken by
technical committee 42 to provide a standard covering the high voltage testing of low-
voltage equipment. It is based on IEC 60-1 (1989). The standard is in two parts. Part 1
covers general definitions and requirements, where sections 1 to 3 may be applicable to
all kinds of electrical equipment, sections 4 to 6 apply to electrical equipment without
voltage limiting devices, section 7 applies to voltage limiting devices alone, and section 8
applies to equipment incorporating non-linear or voltage limiting devices. Part 2 covers
measuring systems and test apparatus (in preparation).
This standard includes high-voltage and impulse current testing as well as a combination
of both.
This standard will be of special interest to product committees such as TC 2, SC 12B,
SC 17B, SC 17D, TC 22, TC 23, SC 37A, TC 61, TC 64, TC 65, SC 66E and TC 74.
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1180-1 ©IEC – 13 –
HIGH-VOLTAGE TEST TECHNIQUES
FOR LOW-VOLTAGE EQUIPMENT
Part 1: Definitions, test and procedure requirements
SECTION 1: GENERAL
1.1 Scope
of IEC 1180 is applicable to:
This pa rt
– dielectric tests with direct voltage;
dielectric tests with alternating voltage;
–
– dielectric tests with impulse voltage;
– tests with impulse current;
– tests with combinations of the above.
This standard is applicable only to tests on equipment having a rated voltage of not more
than 1 kV a.c. or 1,5 kV d.c.
This standard is mainly applicable to type testing. It may also be applied or adapted for
sample and routine testing as specified by the relevant technical committee.
It is not intended to be used for electromagnetic compatibility tests on electric or electronic
equipment.
This standard provides the relevant technical committees as far as possible with:
defined terms of both general and specific applicability;
–
– general requirements regarding test objects and test procedures;
methods for generation and measurement of test voltages and currents;
-
– test procedures;
methods for the evaluation of test results and to indicate criteria for acceptance;
-
requirements concerning approved measuring devices and checking methods.
–
Alternative test procedures may be required and these shall be specified by the relevant
technical committees.
1.2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this part of IEC 1180. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
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1180-1 © IEC
agreements based on this part of IEC 1180 are encouraged to investigate the possibility of
applying the most recent editions of the normative documents indicated below. Members
of IEC and ISO maintain registers of currently valid International Standards.
Environmental testing. Part 1: General and guidance.
IEC 68-1: 1988,
IEC 270: 1981, Partial discharge measurements
Insulation co-ordination within low-voltage systems including clearances
IEC 664: 1980,
and creepage distances for equipment.
Amendment No. 1, 1989.
SECTION 2: DEFINITIONS
2.1 Impulse techniques and insulation
2.1.1 Impulse
An intentionally applied aperiodic transient voltage or current which usually rises rapidly to
a peak value and then falls more slowly to zero.
NOTE - The term "impulse" is distinguished from the term "surge", which refers to transients occurring in
electrical equipment or networks in service.
2.1.2 Partial breakdown
This phenomenon may occur when solid insulation is stressed by impulse voltages. It is
indicated by a stepwise reduction in impulse voltage waveform which occurs earlier in time
in successive impulses, or by other effects specified by the relevant technical committee.
This indicates progressive deterioration of the insulation.
[I EV 441-17-31]
2.1.3 Clearance
The shortest distance in air between two conductive parts.
2.1.4 Creepage distance [IEV 151-03-37]
The shortest distance along the surface of an insulating material between two conductive
parts.
2.1.5 Solid insulation
Solid insulating material interposed between two conductive parts.
2.2 Characteristics related to disruptive discharge and test voltages
2.2.1 Disruptive discharge
The failure of insulation under electrical stress, in which the discharge completely bridges
the insulation under test, reducing the voltage between the electrodes practically to zero.
It applies to electrical breakdown in solid, liquid and gaseous dielectrics and combinations
of these.
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1180-1 © IEC –17 –
NOTES
1 Non-sustained disruptive discharges in which the test object is momentarily bridged by a spark or arc
may occur. During these events, the voltage across the test object is momentarily reduced to zero or to a
very small value. Depending on the characteristics of the test circuit and the test object, a recovery of
dielectric strength may occur and may even permit the test voltage to reach a higher value. Such an event
should be interpreted as a disruptive discharge unless otherwise specified by the relevant technical
committee.
2 Some non-disruptive discharges are termed "partial discharges" and are dealt with in IEC 270.
3 The term "sparkover" is used when a disruptive discharge occurs in a gaseous or liquid medium.
ace of a dielectric in a
The term "flashover is used when a disruptive discharge occurs over the su rf
gaseous or liquid medium.
The term "puncture" is used when a disruptive discharge occurs through a solid dielectric.
Characteristics of the test voltage
2.2.2
Those characteristics specified in this standard in order to define the different types of test
voltage.
2.2.2.1 Prospective characteristics of a test voltage
The characteristics which would have been obtained if no disruptive discharge or
operation of a voltage limiting device had occurred. When a prospective characteristic is
referred to, this shall always be stated.
2.2.2.2 Actual characteristics of a test voltage
Those which occur during the test at the terminals of the test object.
2.2.2.3 Value of the test voltage
The value of the test voltage is defined in 4.1.1, 5.1.1 and 6.1.1.1.
2.2.3 Disruptive discharge voltage
The value of the test voltage causing disruptive discharge, as specified, for the various
tests by 4.3.2, 5.3.2 and 6.3.3.
2.2.4 Withstand voltage
A specified voltage value which characterizes the insulation of the object with regard to a
withstand test.
Unless otherwise specified, withstand voltages are referred to the standard reference
atmosphere (see 3.3.1).
2.2.5 Assured disruptive discharge voltage
rformance with regard to a
A specified prospective voltage value which characterizes its pe
disruptive discharge test. Unless otherwise specified, assured disruptive discharge
voltages refer to standard reference atmospheric conditions (see 3.3.1).
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1180-1 © I EC - 19 -
SECTION 3: GENERAL REQUIREMENTS RELATING TO TEST PROCEDURES
AND TEST OBJECTS
3.1 General requirements for test procedures
The test procedures applicable to particular types of test objects, for example, the polarity
to be used, the preferred order if both polarities are to be used, the number of applications
and the interval between applications, and any conditioning and preconditioning, shall be
specified by the relevant technical committee, having regard to such factors as:
- the required accuracy of test results;
- the random nature of the observed phenomenon and any polarity dependence of
the measured characteristics;
- the possibility of progressive deterioration with repeated voltage applications.
3.2 General arrangement of the test object
At the time of the test, the test object shall be complete in all essential details and it shall
have been processed in the normal manner for similar equipment.
Unless otherwise specified by the relevant technical committee, the test object should be
dry and clean and in an environmentally stable condition. If not otherwise specified by
the relevant technical committee, the test shall be made at ambient temperature and the
procedure for voltage application shall be as specified in the relevant clauses of this
standard.
3.3 Atmospheric conditions
3.3.1 Standard reference atmosphere
The standard reference atmosphere according to IEC 68-1 is:
temperature to = 20 °C
pressure po = 101,3 kPa (1 013 mbar)
NOTE - A pressure of 101,3 kPa corresponds to the height of 760 mm in a mercury barometer at 0 °C.
If the barometer height is H mm of mercury, the atmospheric pressure in Pascals is approximately:
p = (0,1333 H) kPa
Correction for temperature is considered to be negligible with respect to the height of the mercury column.
3.3.2 Atmospheric correction factor
The disruptive discharge of clearances depends upon the atmospheric conditions. Usually,
the disruptive discharge voltage for a given path in air is increased with increase in air
density. When the relative humidity exceeds about 75 %, the disruptive discharge voltage
becomes irregular, especially when the disruptive discharge occurs across an insulating
surface.
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21 –
1180-1 © IEC –
By applying the correction factor, a disruptive discharge voltage measured in given test
be converted to the value which would have
conditions (temperature t, pressure p) may
o, po). Conversely, a
been obtained under the standard reference atmospheric conditions (t
test voltage specified for given reference conditions can be converted into the equivalent
value under the test conditions.
K.
The disruptive discharge voltage is proportional to the air density correction factor
to be applied
U
if not otherwise specified by the relevant technical committee, the voltage
during a test on clearances is determined by multiplying the specified withstand voltage Uo
by K:
U =UoK
are corrected to those applicable for
U
Similarly, measured disruptive discharge voltages
by dividing by K:
standard reference atmosphere U0
U0 = U/K
shall always contain a record of the actual atmospheric conditions
The test report
(temperature, pressure and relative humidity) during the test and the correction factor
applied.
depends on the relative air density according to:
The air density correction factor K
273+ to p
<_ 1,1
= for 0,9 <_
K
273 + t po
Po
are expressed in degrees Celsius and the atmospheric
where temperatures t and to
in the same unit (kPa or mbar). For pressure ratios outside this range,
pressures p and po
further information is given in Amendment 1 to IEC 664.
NOTE - IEC 664 gives information on the relationship between barometric pressure and altitude.
is much different from the unity, and in cases where both
When the correction factor K
clearances and solid insulation are involved, it is left to the relevant technical committee to
decide on the test procedure necessary to ensure that the insulation is stressed to the
specified level.
SECTION 4: TESTS WITH DIRECT VOLTAGE
4.1 Definitions for direct voltage tests
4.1.1 Value of the test voltage
The arithmetic mean value.
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1180-1 © IEC - 23 -
4.1.2 Ripple
The periodic deviation from the arithmetic mean value of the voltage. The amplitude of the
ripple is defined as half the difference between the maximum and minimum values. The
ripple factor is the ratio of the ripple amplitude to the arithmetic mean value.
4.2 Test voltage
4.2.1 Requirements for the test voltage
4.2.1.1 Voltage shape
direct voltage with not more than
The test voltage, as applied to the test object, shall be a
3% ripple factor, unless otherwise specified by the relevant technical committee. Note that
the ripple factor may be affected by the presence of the test object and by the test
conditions.
4.2.1.2 Tolerance
If not otherwise specified by the relevant technical committee, a tolerance of ±3 % is
acceptable between the specified and the measured test voltage values.
NOTE - It is emphasized that the tolerance constitutes the permitted difference between the specified
value and that actually measured. This difference should be distinguished from the measuring error which
is the difference between the measured value and the true value.
Generation and measurement of the test voltage
4.2.2
The test voltage is generally obtained by means of rectifiers. The requirements to be met
by the test voltage source depend considerably upon the type of apparatus which is to be
tested and on the test conditions. These requirements are determined mainly by the value
and nature of the test current to be supplied.
The source characteristics should be such as to permit charging of the capacitance of the
rt time. In the case of objects having high capacitance,
test object in a reasonably sho
charging times of several minutes must, however, sometimes be accepted for type tests.
The source, including its storage capacitance, should also be adequate to supply the leak-
age, absorption and partial discharge currents without voltage drops exceeding 5 %.
The characteristics of the test voltage source and the calibration of the measuring system
shall be verified in accordance with the requirements of future IEC 1180-2.
4.3 Test procedures
4.3.1 Withstand voltage tests
The voltage shall be applied to the test object starting at a value sufficiently low to prevent
any effect of overvoltage due to switching transients. It should be raised sufficiently slowly
as to permit reading of the instruments, but not so slowly as to cause unnecessary prolon-
gation of stressing of the test object near to the test voltage.
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1180-1 ©IEC – 25 –
For type tests, these requirements are, in general, met if the rate of rise is about 5 % of
the estimated final voltage per second when the applied voltage is above 75 % of this
voltage. It shall be maintained for the specified time and then reduced by discharging the
smoothing capacitor and the test object through a suitable resistor.
The test duration shall be specified by the relevant technical committee taking into
consideration that the time to reach the steady state voltage distribution depends on the
resistances and capacitances of the test object components.
The polarity of the voltage or the order in which voltages of each polarity are applied, and
any required deviation from the above specifications, should be specified by the relevant
technical committee.
Unless otherwise specified by the relevant technical committee, the requirements of the
test are satisfied if no disruptive discharge occurs on the test object.
4.3.2 Assured disruptive discharge voltage tests
The requirements of the test are generally satisfied if the value of the recorded disruptive
discharge voltage is not higher than the assured disruptive discharge voltage on each one
of a specified number of voltage applications.
SECTION 5: TESTS WITH ALTERNATING VOLTAGE
for alternating voltage tests
5.1 Definitions
5.1.1 Peak value
The maximum value.
5.1.2 R.M.S value
The square root of the mean value of the square of the voltage values during a complete
cycle.
5.2 Test voltage
5.2.1 Requirements for the test voltage
5.2.1.1 Voltage waveshape
The alternating test voltage, as applied to the test object, should generally have a
frequency in the range 45 Hz to 65 Hz, normally referred to as power-frequency test volt-
age. Special tests may be required at frequencies considerably below or above this range,
as specified by a technical committee.
The voltage shape shall approximate to a sinusoid with both half-cycles closely alike. This
requirement is considered met if the ratio of peak to r.m.s. values is equal to 't 5 %.
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1180-1 ©IEC - 27 -
5.2.1.2 Value of the test voltage
The peak value divided by
NOTE - The relevant technical committee may require measurement of the r.m.s. value of the test voltage
instead of the peak value for cases where the r.m.s. value may be of importance. Such cases are, for
instance, when thermal effects are involved.
5.2.1.3 Tolerance
If not otherwise specified by the relevant technical committee, a tolerance of ± 3 % is
acceptable between the specified and the measured test voltage values.
NOTE - It is emphasized that the tolerance constitutes the permitted difference between the specified
value and that actually measured. This difference should be distinguished from the measuring error which
is the difference between the measured value and the true value.
Generation and measurement of the test voltage
5.2.2
5.2.2.1 General requirements
The voltage in the test circuit should be stable enough to be practically unaffected by vary-
ing leakage currents.
5.2.2.2 Requirements for the test circuit
At the test voltage, the prospective short-circuit current at the test object shall be at least
0,1 A r.m.s. for type tests.
The characteristics of the generator shall be verified in accordance with the requirements
of the future IEC 1180-2.
NOTES
The voltage stability can be verified by the direct recording of the voltage applied to the test object.
1
2 Where high capacitive loading limits the a.c. test voltage, it may be necessary to perform a d.c. test as
an alternative (see clause 5.2). The relevant technical committee shall specify the equivalent d.c. test
voltage.
5.2.3 Measurement of the test voltage
The calibration of the measuring system shall be verified in accordance with the require-
ments of the future IEC 1180-2.
5.3 Test procedures
5.3.1 Withstand voltage tests
The voltage shall be applied to the test object starting at a value sufficiently low to prevent
any effect of overvoltages due to switching transients. It shall be raised sufficiently slowly
as to permit accurate reading of the measuring instrument but not so slowly as to cause
unnecessary prolongation of the stressing of the test object near to the test voltage.
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1180-1 © I EC – 29 –
For type tests, these requirements are, in general, met if the rate of the rise is about 5 %
of the estimated final test voltage per second, when the applied voltage is above 75 % of
this voltage. It shall be maintained for the specified time and then rapidly decreased, but
not suddenly interrupted, as this may generate switching transients which could cause
damage or erratic test results.
The test duration is to be specified by the relevant technical committee, and should be
independent of the frequency in the range from 45 Hz to 65 Hz.
Unless otherwise specified by the relevant technical committee the requirements of the
test are satisfied if no disruptive discharge occurs on the test object.
Assured disruptive discharge voltage tests
5.3.2
The requirements of the test are generally satisfied if the value of the recorded disruptive
discharge voltage is not higher than the assured disruptive discharge voltage on each one
of a specified number of voltage applications.
SECTION 6: TESTS WITH IMPULSE VOLTAGE
6.1 Definitions for impulse tests
6.1.1 Definitions of general applicability
These definitions apply to impulses without oscillations or overshoot or to the mean curve
drawn through the oscillations and overshoot.
6.1.1.1 Value of the test voltage
For an impulse without oscillations, its peak value.
The determination of the peak value, in the case of oscillations or overshoot on standard
impulses, is considered in 6.2.2.
For other impulse shapes, the relevant technical committee shall define the value of the
test voltage, taking into account the type of test and test object.
6.1.1.2 Virtual front time Ti
between the instants when the impulse is 30 % and 90 % of the
1,67 times the interval T1
peak value (points A and B, figure 1).
6.1.1.3 Virtual origin 01
The instant preceding that corresponding to point A (figure 1) by a time 0.3 T 1 . This is the
intersection with the time axis of a straight line drawn through the reference points A and
B on the front.
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1180-1 ©IEC
T2
6.1.1.4 Virtual time to half-value
0 1 and the instant when the voltage has
The time interval between the virtual origin
decreased to half the peak value.
6.2 Test voltage
6.2.1 Standard impulse
A full impulse having a virtual front time of 1,2 its and a virtual time to half-value of 50 Ns.
It is described as a 1,2/50 impulse. Other waveshapes may be specified by the relevant
technical committee.
6.2.2 Tolerances on standard impulse
If not otherwise decided by the relevant technical committee, the following differences are
accepted between specified values for the standard impulse and those actually recorded:
± 3 %
Peak value
± 30 %
Front time
Time to half-value ± 20 %
NOTE - It is emphasized that the tolerances on the peak value, front time and time to half-value constitute
the permitted differences between specified values and those actually recorded by measurements. These
differences should be distinguished from measuring errors which are the difference between the values
actually recorded and the true values.
With some test circuits, oscillations or an overshoot may occur at the crest of the impulse
(see figure 2 a-d). If the frequency of such oscillations is not less than 0,5 MHz, or the
a mean curve should be drawn as in figures 2 a-d, and
duration of overshoot not over 1 ps,
for the purpose of measurement, the maximum amplitude of this curve is chosen as the
peak value defining the value of the test voltage. Other waveshapes may occur due to
load characteristics, guidance for the interpretation of such waveshapes shall be given by
the relevant technical committee.
Overshoot or oscillations in the neighbourhood of the crest are acceptable provided their
single peak amplitude is not larger than 5 % of the peak value. In commonly used impulse
of the wavefront during which the voltage does
rt
generator circuits, oscillations on that pa
not exceed 90 % of the peak value have generally negligible influence on test results.
The impulse should be essentially unidirectional, but see note.
NOTE - In specific cases, such as during tests on low impedance objects, e.g. large capacitors, it may be
im
...
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