IEC 62576:2009
(Main)Electric double-layer capacitors for use in hybrid electric vehicles - Test methods for electrical characteristics
Electric double-layer capacitors for use in hybrid electric vehicles - Test methods for electrical characteristics
IEC 62576:2009 describes the methods for testing electrical characteristics of electric double-layer capacitor cells (hereinafter referred to as capacitor) to be used for peak power assistance in hybrid electric vehicles.
Condensateurs électriques à double couche pour véhicules électriques hybrides - Methodes d'essai des caractéristiques électriques
La CEI 62576:2009 décrit les méthodes d'essai des caractéristiques électriques des cellules de condensateur électrique à double couche (ci-après dénommé "condensateur") utilisées pour l'assistance en puissance de crête dans les véhicules électriques hybrides.
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IEC 62576 ®
Edition 1.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electric double-layer capacitors for use in hybrid electric vehicles – Test
methods for electrical characteristics
Condensateurs électriques à double couche pour véhicules électriques
hybrides – Méthodes d'essai des caractéristiques électriques
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IEC 62576 ®
Edition 1.0 2009-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electric double-layer capacitors for use in hybrid electric vehicles – Test
methods for electrical characteristics
Condensateurs électriques à double couche pour véhicules électriques
hybrides – Méthodes d'essai des caractéristiques électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 31.090.99; 43.120 ISBN 978-2-88910-766-7
– 2 – 62576 © IEC:2009
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 Tests and measurement procedures.10
4.1 Capacitance, internal resistance, and maximum power density.10
4.1.1 Circuit for measurement .10
4.1.2 Test equipment.11
4.1.3 Measurement procedure .11
4.1.4 Measurement.12
4.1.5 Calculation method for capacitance .12
4.1.6 Calculation method for internal resistance .12
4.1.7 Calculation method for maximum power density .13
4.2 Voltage maintenance characteristics .13
4.2.1 Circuit for measurement .13
4.2.2 Test equipment.14
4.2.3 Measurement procedures .14
4.2.4 Measurement.15
4.2.5 Calculation of voltage maintenance rate .15
4.3 Energy efficiency.15
4.3.1 Circuit for test.15
4.3.2 Test equipment.15
4.3.3 Measurement procedures .16
4.3.4 Measurement.17
4.3.5 Calculation of energy efficiency .17
Annex A (informative) Endurance test (continuous application of rated voltage at high
temperature) .18
Annex B (informative) Heat equilibrium time of capacitors.20
Annex C (informative) Charging/discharging efficiency and measurement current.22
Annex D (informative) Procedures for setting the measurement current of capacitor
with uncertain nominal internal resistance.24
Bibliography.25
Figure 1 – Basic circuit for measuring capacitance, internal resistance and maximum
power density .10
Figure 2 – Voltage-time characteristics between capacitor terminals in capacitance and
internal resistance measurement .11
Figure 3 – Basic circuit for measuring the voltage maintenance characteristics.13
Figure 4 – Time characteristics of voltage between capacitor terminals in voltage
maintenance test .14
Figure 5 – Voltage-time characteristics between capacitor terminals in
charging/discharging efficiency test .
Figure B.1 – Heat equilibrium times of capacitors (85 °C→25 °C) .20
Figure B.2 – Heat equilibrium times of capacitors (–40 °C→25 °C) .21
Figure B.3 – Temperature changes of capacitors' central portions (85 °C→25 °C) .21
62576 © IEC:2009 – 3 –
Figure B.4 – Temperature changes of capacitors' central portions (–40 °C→25 °C) .21
Table D.1 – Example of setting current for measurement of capacitor .24
– 4 – 62576 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRIC DOUBLE-LAYER CAPACITORS
FOR USE IN HYBRID ELECTRIC VEHICLES –
TEST METHODS FOR ELECTRICAL CHARACTERISTICS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62576 has been prepared by IEC technical committee 69: Electric
road vehicles and electric industrial trucks.
The text of this standard is based on the following documents:
CDV Report on voting
69/158/CDV 69/162/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
62576 © IEC:2009 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
– 6 – 62576 © IEC:2009
INTRODUCTION
The Electric double-layer capacitor (EDLC) is a promising energy storage system for hybrid
electric vehicles (HEVs), and EDLC-installed HEVs have begun to be commercialized with an
eye to improving fuel economy by recovering regenerative energy. Although a standards
series (IEC 62391 series) for EDLC already exists, those for HEVs involve patterns of use,
usage environment, and values of current that are quite different from those assumed in the
existing standards. Standard evaluation and test methods will be useful for both the auto
manufacturers and capacitor suppliers to speed up the development and lower the costs of
such EDLCs. With these points in mind, this standard aims to provide basic and minimum
specifications in terms of the methods for testing electrical characteristics, and to create an
environment that supports expanding market of HEVs and large capacity EDLCs. Additional
practical test items to be standardized should be reconsidered after technology and market
stabilization of EDLCs for HEVs. In terms of endurance that is important in practical use, just
basic concept is set forth in the informative annexes.
62576 © IEC:2009 – 7 –
ELECTRIC DOUBLE-LAYER CAPACITORS
FOR USE IN HYBRID ELECTRIC VEHICLES –
TEST METHODS FOR ELECTRICAL CHARACTERISTICS
1 Scope
This standard describes the methods for testing electrical characteristics of electric double-
layer capacitor cells (hereinafter referred to as capacitor) to be used for peak power
assistance in hybrid electric vehicles.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
Amendment 1(1992)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
reference temperature
reference temperature (°C) to be used in the test
3.2
ambient temperature
ambient temperature of the surrounding space in which a capacitor is placed
3.3
upper category temperature
highest ambient temperature that a capacitor is designed to operate continuously
3.4
lower category temperature
lowest ambient temperature that a capacitor is designed to operate continuously
3.5
applied voltage
voltage (V) applied between the terminals of a capacitor
3.6
rated voltage
U
R
maximum d.c. voltage (V) that may be applied continuously for a certain time under the upper
category temperature to a capacitor so that a capacitor can exhibit specified demand
characteristics. This voltage is the setting voltage in capacitor design
NOTE The endurance test using the rated voltage is described in Annex A.
– 8 – 62576 © IEC:2009
3.7
charge current
I
c
current (A) required to charge a capacitor
3.8
discharge current
I
d
current (A) required to discharge a capacitor
3.9
stored energy
energy (J) stored in a capacitor
3.10
charge accumulated electrical energy
amount of charged energy (J) accumulated from the beginning to the end of charging
3.11
discharge accumulated electrical energy
amount of discharged energy (J) accumulated from the beginning to the end of discharging
3.12
calculation start voltage
voltage (V) at a selected start point for calculating the characteristics including capacitance
under a state of voltage decrease during discharge
3.13
calculation end voltage
voltage (V) at a selected end point for calculating the characteristics including capacitance
under a state of voltage decrease during discharge
3.14
capacitance
ability of a capacitor to store electrical charge (F)
3.15
nominal capacitance
C
N
nominal capacitance value (C ) to be used in design and measurement condition setting (F),
N
generally, at the reference temperature
3.16
internal resistance
combined resistance (Ω) of constituent material specific resistance and inside connection
resistance of a capacitor
3.17
nominal internal resistance
R
N
nominal value of the internal resistance (R ) to be used in design and measurement condition
N
setting (Ω), generally at the reference temperature
3.18
constant voltage charging
method of charging a capacitor at specified voltage continuously
62576 © IEC:2009 – 9 –
3.19
pre-conditioning
discharging and storage of a capacitor under specified ambient conditions (temperature,
humidity, and pressure) before testing
NOTE Generally, pre-conditioning implies that a capacitor is discharged and stored until its inner temperature
attains thermal equilibrium with the surrounding temperature, before its electrical characteristics are measured.
3.20
voltage treatment
voltage application before measurement of a capacitor’s electrical characteristics
NOTE Generally, this treatment is applied to a capacitor that has been stored for a long time or to a capacitor
whose history is not clear.
3.21
post-treatment (recovery)
discharging and storage of a capacitor under specified ambient conditions (temperature,
humidity, and pressure) after tests
NOTE Generally, post-treatment implies that a capacitor is discharged and stored until its inner temperature attains
thermal equilibrium with the surrounding temperature before its electrical characteristics are measured.
3.22
charging efficiency
efficiency under specified charging conditions, and ratio (%) of stored energy to charge
accumulated electrical energy. This value is calculated from the internal resistance of a
capacitor
NOTE Refer to Equation C.8 in Annex C.
3.23
discharging efficiency
efficiency under specified discharging conditions, and ratio (%) of discharge accumulated
electrical energy to stored energy. This value is calculated from the internal resistance of a
capacitor
NOTE Refer to Equation C.10 in Annex C.
3.24
energy efficiency
E
f
ratio (%) of discharge accumulated electrical energy to charge accumulated electrical energy
under specified charging and discharging conditions
3.25
voltage maintenance characteristics
voltage maintenance characteristics of a capacitor when its terminals are open after charging
3.26
voltage maintenance rate
ratio of voltage maintenance
ratio of the voltage at the open-ended terminals to the charge voltage after a specified time
period subsequent to the charging of a capacitor
3.27
power density
electrical power per unit mass (W/kg) or per unit volume (W/l) that can be recovered from a
charged capacitor
– 10 – 62576 © IEC:2009
3.28
rated power density
specified maximum power density (W/kg or W/l). Generally, it is calculated by using the
nominal internal resistance and the rated voltage
3.29
maximum power density
P
dm
maximum power density (W/kg or W/l) that can be recovered from a charged capacitor.
Generally, it is calculated by using the internal resistance and the rated voltage
4 Tests and measurement procedures
4.1 Capacitance, internal resistance, and maximum power density
4.1.1 Circuit for measurement
The capacitance and the internal resistance shall be measured by using the constant current
charging and discharging methods. Figure 1 shows the basic circuit to be used for the
measurement.
Power supply
a)
A
S
I
CC
+
V
Cx
b)
U
CV
IEC 1597/09
Key
I constant-current
CC
U constant-voltage
CV
A d.c. ammeter
V d.c. voltage recorder
S changeover switch
Cx capacitor under test
constant current discharger
a) constant current charging
b) constant voltage charging
Figure 1 – Basic circuit for measuring capacitance,
internal resistance and maximum power density
62576 © IEC:2009 – 11 –
4.1.2 Test equipment
The test equipment shall be capable of constant current charging, constant voltage charging,
constant current discharging, and continuous measurement of the current and the voltage
between the capacitor terminals in time-series as shown in Figure 2. The test equipment shall
be able to set and measure the current and the voltage with the accuracy equal to ± 1 % or
less.
The power supply shall provide the constant charge current for the capacitor charge with
95 % efficiency, set the duration of constant voltage charge, and provide a discharge current
corresponding to the specified-discharge efficiency. The d.c. voltage recorder shall be
capable of conducting measurements and recording with a 5 mV resolution and sampling
interval of 100 ms or less.
U
R
ΔU
U
ΔU
U
Magnified figure
Time (s)
T
CV
IEC 1598/09
Key
U rated voltage (V)
R
U calculation start voltage (V)
U calculation end voltage (V)
ΔU voltage drop (V)
T constant voltage charging duration (s)
CV
Figure 2 – Voltage-time characteristics between capacitor
terminals in capacitance and internal resistance measurement
4.1.3 Measurement procedure
Measurements shall be carried out in accordance with the following procedures using the test
equipment specified in 4.1.2.
a) Pre-conditioning
Before measurement, the capacitors shall be fully discharged and then incubated for 2 h to
6 h under the reference temperature, set at 25 °C ± 2 °C, as specified in 5.2 in IEC 60068-
1, or that specified by the related standards.
NOTE 1 The heat equilibrium time which provides a reference for the soaking time is described in Annex B.
b) Sample setting
Fit the sample capacitors with the test equipment.
c) Test equipment set-up
Voltage (V)
– 12 – 62576 © IEC:2009
Unless specified otherwise by related standards, the test equipment shall be set-up in the
following manner.
1) Set the constant current I for charging. At this current, the capacitors shall be able to
c
charge with 95 % charging efficiency based on their nominal internal resistance R .
N
The current value is calculated by I =U /38R .
c R N
NOTE 2 The general concept for 95 % charging or discharging efficiency is described in Annex C. When
the rated value of internal resistance of a capacitor is uncertain, the current for the measurement can be
set according to the advisable procedures described in Annex D.
2) Set the maximum voltage for constant current charging as the rated voltage U .
R
3) Set the duration of constant voltage charging T to 300 s.
CV
4) Set the constant current discharge value. This value shall allow for a 95 % discharging
efficiency based on the capacitor’s nominal internal resistance R , and is calculated
N
by I =U /40R .
d R N
5) Set the sampling interval to 100 ms or less, and set the test-equipment so as to
measure the voltage drop characteristics up to 0,5 U .
R
4.1.4 Measurement
After the setting as specified above, the voltage-time characteristics between capacitor
terminals as shown in Figure 2 shall be measured.
4.1.5 Calculation method for capacitance
The capacitance C shall be calculated using Equation (1) based on the voltage-time
characteristics between capacitor terminals obtained in 4.1.4.
NOTE This calculation method is called “energy conversion capacitance method.”
2 W
(1)
C =
2 2
(0,9 U ) − (0,7 U )
R R
where
C is the capacitance (F) of capacitor ;
) to
W is the measured discharged energy (J) from calculation start voltage (0,9 U
R
calculation end voltage (0,7 U );
R
U is the rated voltage (V).
R
4.1.6 Calculation method for internal resistance
The internal resistance R shall be calculated using Equation (2) based on the voltage-time
characteristics between capacitor terminals obtained in 4.1.4.
ΔU
R = (2)
I
d
where
R is the internal resistance (Ω) of capacitor;
I is the discharge current (A).
d
ΔU Apply the straight-line approximation to the voltage drop characteristics from the
calculation start voltage (0,9 U ) to the calculation end voltage (0,7 U ) by using the
R R
least squares method. Obtain the intercept (voltage value) of the straight line at the
discharge start time. ΔU is the difference of voltages (V) between the intercept
voltage value and the set value of constant voltage charging.
62576 © IEC:2009 – 13 –
NOTE This calculation method is called “least squares internal resistance method.”
4.1.7 Calculation method for maximum power density
The maximum power density P is calculated by using the internal resistance value
dm
calculated in 4.1.6 and Equation (3).
NOTE This calculation method is called “matched impedance power density method.”
0,25 U
R
(3)
P =
dm
RM
where
P
dm is the maximum power density of capacitor (W/kg or W/l) ;
U is the rated voltage (V);
R
R is the calculated internal resistance (Ω);
M is the mass or volume of capacitor (kg or l).
4.2 Voltage maintenance characteristics
4.2.1 Circuit for measurement
Figure 3 shows the basic circuit for measuring the voltage maintenance characteristics.
Power supply
a)
S
I
CC
+
V Cx V
1 2
b)
U
CV
IEC 1599/09
Key
I constant-current
CC
U constant-voltage
CV
V V d.c. voltmeter
1 2
S changeover switch
Cx capacitor under test
a) constant current charging
b) constant voltage charging
Figure 3 – Basic circuit for measuring the voltage maintenance characteristics
– 14 – 62576 © IEC:2009
4.2.2 Test equipment
The test equipment shall be capable of constant current charging, constant voltage charging,
and continuous measurement of the voltage between the capacitor terminals in time-series as
shown in Figure 4. The power supply shall provide the constant charge current for the
capacitor charge with 95 % efficiency and set the duration of constant voltage charging. The
test equipment shall be able to set and measure the current and the voltage by the accuracy
equal to ±1 % or less.
The d.c. voltage recorders V and V shall have a resolution of 5 mV or less for voltage
1 2
measurement. The input impedance of the recorder shall be sufficiently high so that
measurement errors are negligible.
U
R
Time (s)
T T T
CC1 CV1 OC1
IEC 1600/09
Key
U rated voltage (V)
R
T charging duration with 95 % efficiency (s)
CC1
T duration of constant voltage charging (s)
CV1
T duration of measurement (h)
OC1
Figure 4 – Time characteristics of voltage between capacitor
terminals in voltage maintenance test
4.2.3 Measurement procedures
The measurements shall be carried out in accordance with the following procedures using the
test equipment specified in 4.2.2.
a) Pre-conditioning
Before measurement, the capacitors shall be fully discharged and then incubated for 2 h
to 6 h under the reference temperature, set at 25 °C ± 2 °C, as specified in 5.2 in
IEC 60068-1, or that specified by the related standards.
NOTE 1 The heat equilibrium time which provides a reference for the soaking time is described in Annex B.
b) Sample setting
Fit the sample capacitors with the test equipment.
c) Test equipment set-up
Voltage (V)
62576 © IEC:2009 – 15 –
Unless specified otherwise by related standards, the test equipment shall be set-up in the
following manner.
1) Set the constant current value for charging. At this current, the capacitors shall be able
to charge with 95 % charging efficiency based on their nominal internal resistance. The
current value is calculated by I =U /38R .
c R N
NOTE 2 The general concept for 95 % charging or discharging efficiency is described in Annex C. When
the rated value of internal resistance of a capacitor is uncertain, the current for the measurement can be
set according to the advisable procedures described in Annex D.
2) Set the maximum voltage for constant current charging to the rated voltage U .
R
3) Set the duration of constant voltage charging T to 300 s.
CV1
4) After specified charging duration, set the capacitor terminals open.
4.2.4 Measurement
After the setting as specified above, measure the voltage between capacitor terminals when
T in Figure 4 is 72 h.
OC1
4.2.5 Calculation of voltage maintenance rate
The voltage maintenance rate A is calculated by Equation (4).
U
end
A = ×100 (4)
U
R
where
A is the voltage maintenance rate (%);
U is the voltage between open capacitor terminals after 72 h (T ) has elapsed ;
end OC1
U is the rated voltage (V).
R
4.3 Energy efficiency
4.3.1 Circuit for test
The energy efficiency test shall be conducted by the constant current charging and
discharging. Figure 1 shows the basic circuit required for this test.
4.3.2 Test equipment
The test equipment shall be as specified in 4.1.2.
The test equipment shall be capable of constant current charging, constant voltage charging,
constant current discharging, and continuous measurement of the current and the voltage
between the capacitor terminals in time-series as shown in Figure 5. The test equipment shall
be able to set and measure the current and the voltage by the accuracy equal to ±1 % or less.
The power supply shall provide the constant charge current for the capacitor charge with
95 % efficiency, set the duration of constant voltage charge, and provide a discharge current
corresponding to the specified discharge efficiency. The d.c. voltage recorder shall be
capable of conducting measurements and recording with a 5 mV resolution and sampling
interval of 100 ms or less.
– 16 – 62576 © IEC:2009
U
R
Constant current
discharge
0,5U
R
t
t t 0,5UR
0 UR
Time (s)
T T T T T
CC11 CV11 CC12 CV12 CC13
Time (s)
IEC 1601/09
Key
U rated voltage (V)
R
T constant current charging duration (s) up to 0,5U
CC11 R
T constant voltage charging duration (s) up to 0,5U
CV11 R
T constant current charging duration (s) up to U
CC12 R
T constant voltage charging duration (s) at U
CV12 R
T constant current discharging duration (s) from U to 0,5U
CC13 R R
Figure 5 – Voltage-time characteristics between capacitor terminals
in charging/discharging efficiency test
4.3.3 Measurement procedures
The measurements shall be carried out in accordance with the following procedures by using
the test equipment specified in 4.3.2.
a) Pre-conditioning
Before measurement, the capacitors shall be fully discharged and then incubated for 2 h to
6 h under the reference temperature, set at 25 °C ± 2 °C, as specified in 5.2 in IEC 60068-
1, or that specified by the related standards.
NOTE 1 The heat equilibrium time which provides a reference for the soaking time is in Annex B.
b) Sample setting
Fit the sample capacitors with the test equipment.
c) Test equipment set-up
Current (A) Voltage (V)
62576 © IEC:2009 – 17 –
Unless specified otherwise by related standards, the test equipment shall be set up as
follows.
1) Set the constant current for charging from 0 V to 0,5 U and from 0,5 U to U . At this
R R R
current, the capacitors shall be able to charge with 95 % charging efficiency based on
their nominal internal resistance R . The current value is calculated by I =U /38 R .
N c R N
NOTE 2 The general concept for 95 % charging or discharging efficiency is described in Annex C. When
the rated value of internal resistance of a capacitor is uncertain, the current for the measurement can be
set according to the advisable procedures described in Annex D.
2) Set the duration of constant voltage charging T at 0,5U to 300 s, and T at U
CV11 R CV12 R
to 10 s.
3) Set the constant current discharge value. This value shall allow for a 95 % discharging
efficiency based on the capacitor’s nominal internal resistance R and is calculated by
N
I =U /40R .
d R N
NOTE 3 The general concept for 95 % charging or discharging efficiency is described in Annex C. When
the rated value of internal resistance of a capacitor is uncertain, the current for the measurement can be
set according to the advisable procedures described in Annex D.
4) Discharging can be deemed complete when the voltage between the capacitor
terminals reaches 0,5 U .
R
4.3.4 Measurement
After setting up the test equipment as mentioned above, test the following: constant current
charging up to 0,5 U , constant voltage charging at 0,5 U , constant current charging up to
R R
U , constant voltage charging at U , and constant current discharging down to 0,5 U in that
R R R
order. Obtain the charge accumulated electrical energy from 0,5 U (during T and T )
R CC12 CV12
and the discharge accumulated electrical energy during discharging T .
CC13
4.3.5 Calculation of energy efficiency
The energy efficiency E can be obtained by Equation (5) based on the voltage-time and
f
current-time characteristics between 0,5 U to U .
R R
W
d
E = ×100 (5)
f
W
c
where
E is the energy efficiency (%);
f
W is the discharged electrical energy (J) during T period;
d CC13
W can be obtained by Equation (6):
d
t
o,5 U
R
W = I U()t dt (6)
d d
∫
t
U R
W charged electrical energy (J) during T plus T period.
c CC12 CV12
W can be obtained by Equation (7).
c
t
U
R
W = I cU()t dt (7)
c
∫
t
– 18 – 62576 © IEC:2009
Annex A
(informative)
Endurance test (continuous application
of rated voltage at high temperature)
A.1 General
This annex describes the endurance test for continuous application of rated voltage at high
temperature that is a factor to define the rated voltage defined in 3.6.
A.2 Test procedure
A.2.1 Test condition
Unless specified otherwise by related standards, the test conditions shall be as follows.
– test temperature: upper category temperature;
– applied voltage: rated voltage;
– test duration: 1 000 h.
A.2.2 Test procedure
a) Pre-conditioning
Before measurement, the capacitors shall be fully discharged and then incubated for 2 h to
6 h under the reference temperature, which shall be set at 25 °C ± 2 °C, as specified in 5.2
in IEC 60068-1.
b) Initial measurements
The capacitance and the internal resistance shall be measured according to the procedure
specified in 4.1.
c) Testing
Place the capacitors in a chamber at the category upper temperature and apply the rated
voltage for specified duration. Charging up to the specified rated voltage shall be carried
out by applying a current that provides 95 % charging efficiency based on the nominal
internal resistance of the capacitors.
d) Post-treatment (recovery)
After the test is complete, remove the capacitors from the test chamber, discharge
completely and soak them in the reference temperature, set at 25 °C ± 2 °C, as specified
in 5.2 in IEC 60068-1 for 2 h to 6 h.
e) Final measurement
Apart from visual inspection, the capacitance and the internal resistance of the capacitors
shall be measured in accordance with the procedure of 4.1 and the rates of change from
their initially measured values shall be obtained.
A.2.3 Judgment criteria
Unless specified otherwise by delivery contract between the parties, it is advisable that the
capacitance change rate ∆C and internal resistance change rate ∆R shall conform with the
following values.
62576 © IEC:2009 – 19 –
C – C
f i
ΔC = ×100 ≤ 20 %
C
i
where
C is the initial capacitance (F) before the test;
i
C is the capacitance (F) after the test.
f
R – R
f i
ΔR = ×100 ≤ 50 %
R
i
where
R is the initial internal resistance (Ω) before the test;
i
R is the internal resistance (Ω) after the test.
f
– 20 – 62576 © IEC:2009
Annex B
(informative)
Heat equilibrium time of capacitors
B.1 General
This annex describes the heat equilibrium time of capacitors, as a reference in determining
the soaking time for pre-treatment.
B.2 Heat equilibrium time of capacitors
Presuming that the heat equilibrium time, which is the time required for the central portion of a
capacitor to reach the temperature difference from the external temperature within 1 °C, is
dependent on the external dimensions of the capacitor, the temperature changes in the
central portions of capacitors was verified.
The resultant data were obtained by verifying the heat equilibrium time of the central portions
of capacitors that were subjected to a certain environmental temperature. As a result, it was
observed that the equilibrium time was proportional to the magnitudes of the external
dimensions such as diameter for cylindrical capacitors and thickness (thinnest side) for cubic
capacitors. Figure B.1 shows the heat equilibrium times of the capacitors when soaked to
normal room temperature from a high temperature. Figure B.2 shows the heat equilibrium time
of the capacitors when soaked to normal room temperature from a low temperature. In these
figures, the dotted straight lines indicate the presumed longest heat equilibrium time. It is
advisable to use these dotted straight lines as soaking time for pre-conditioning. Figures B.3
and B.4 show the actual measured temperature changes in the capacitors’ central portions.
5,0
Actual measurement results
4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0 20 40 60 80
IEC 1602/09
Diameter or thickness (mm)
Figure B.1 – Heat equilibrium times of capacitors (85 °C→25 °C)
Heat equilibrium time (h)
62576 © IEC:2009 – 21 –
5,0
Actual measurement results
4,5
4,0
3,5
3,0
2,5
2,0
1,5
1,0
0,5
0 20 40 60 80
IEC 1603/09
Diameter or thickness (mm)
Figure B.2 – Heat equilibrium times of capacitors (–40 °C→25 °C)
90 30
Capacitor dimension
∅51 mm × 125 mm (L)
–10
Capacitor dimension
–20 ∅51 mm × 125 mm (L)
–30
–40
–50
0 1 2 3 4 0 1 2 3 4
Time (h)
Time (h)
IEC 1604/09 IEC 1605/09
Figure B.3 – Temperature changes of Figure B.4 – Temperature changes
capacitors' central portions (85 °C→25 °C) of capacitors' central portions
(–40 °C→25 °C)
Temperature of capacitors’ central portions (°C)
Heat equilibrium time (h)
Temperature of capacitors’ central portions (°C)
– 22 – 62576 © IEC:2009
Annex C
(informative)
Charging/discharging efficiency and measurement current
C.1 General
This annex describes the general concept regarding the charging and discharging efficiency
and measured current, which are provided in 4.1.3, 4.2.3, and 4.3.3.
C.2 Charging efficiency, discharging efficiency, and current
Charge Q after charging or discharging for time t at a constant current I, stored energy W, and
energy L lost by resistance R are given by Equations (C.1), (C.2), and (C.3), respectively.
Q = I t (C.1)
Q
W = (C.2)
2C
RQ
L = I R t = (C.3)
t
When a capacitor is charged or discharged to its full capacity at a constant current according
to Equation (C.2) or (C.3), respectively, the energy efficiency P for charging or P for
c d
discharging is given by Equation (C.4) or (C.5), respectively, where R is the internal
resistance and C is the capacitance of the capacitor.
W t
P = = (C.4)
c
W + L t +2RC
W − L 2RC
P = =1 − (C.5)
d
W t
In this standard, the efficiency for charging or discharging is proposed as 95 % after
considering exothermal effect and time consumption for the measurement. The time t required
for charging at 95 % efficiency is given by Equation (C.6) derived from Equation (C.4).
t =38 RC (C.6)
Charge Q stored in a capacitor is given as a product of capacity C and charging voltage U,
thus leading to Equation (C.7). Current I for 95 % charging is given by Equation (C.8) derived
c
from Equations (C.1), (C.6), and (C.7).
Q = CU (C.7)
U
(C.8)
I =
c
38 R
62576 © IEC:2009 – 23 –
Similarly, the time t needed for 95 % discharging is given by Equation (C.9) derived from
Equation (C.5), and the current I needed for 95 % discharging is given by Equation (C.10).
d
t =40 RC (C.9)
U
I = (C.10)
d
40 R
Equations (C.8) and (C.10) are suggested for determing the value of the current for the
charging or discharging test. Once the va
...
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