IEC 63399:2024

Household and similar electrical rice cookers - Methods for measuring the performance

IEC 63399:2024 applies to household and similar electrical rice cookers.
This document defines the main performance characteristics that are of interest to the user and specifies methods for measuring these characteristics.
This document does not specify the requirements for performance.
This document does not apply to the pressure type rice cooker or the micro-pressure rice cooker.
This document does not apply to rice cookers with the rated volume of rice cooker larger than 8 L.
The pressure type rice cooker refers to a rice cooker that cooks at a pressure more than 40 kPa.
The micro-pressure rice cooker refers to a rice cooker that cooks at a pressure larger than 10 kPa but not more than 40 kPa.
This document does not deal with safety requirements (covered in IEC 60335-2-15).

Cuiseurs à riz électrodomestiques et analogues - Méthodes de mesure de l'aptitude à la fonction

L'IEC 63399:2024 s'applique aux cuiseurs à riz électrodomestiques et analogues.
Le présent document définit les caractéristiques d'aptitude à la fonction principales qui sont pertinentes pour l'utilisateur et spécifie les méthodes de mesure de ces caractéristiques.
Le présent document ne spécifie pas les exigences pour l'aptitude à la fonction de ces appareils.
Le présent document ne s'applique pas aux cuiseurs à riz à pression ni aux cuiseurs à riz à micropression.
Le présent document ne s'applique pas aux cuiseurs à riz dont le volume assigné du cuiseur à riz est supérieur à 8 L.
Un cuiseur à riz à pression est un cuiseur à riz qui cuit à une pression supérieure à 40 kPa.
Un cuiseur à riz à micropression est un cuiseur à riz qui cuit à une pression supérieure à 10 kPa, mais inférieure ou égale à 40 kPa.
Le présent document ne traite pas des exigences de sécurité (couvertes par l'IEC 60335-2-15).

General Information

• Status: Published
• Publication Date: 02-Oct-2024
• ICS: 97.040.50 - Small kitchen appliances
• Technical Committee: SC 59L - Small household appliances
• Drafting Committee: PT 63399 - TC 59/SC 59L/PT 63399
• Current Stage: PPUB - Publication issued
• Start Date: 03-Oct-2024
• Completion Date: 01-Nov-2024

Overview

IEC 63399:2024 is the latest international standard established by the International Electrotechnical Commission (IEC) that focuses on household and similar electrical rice cookers. This standard provides clear and standardized methods for measuring the performance of electrical rice cookers, ensuring consistent and reliable evaluation across different manufacturers and product types. Importantly, IEC 63399:2024 applies exclusively to rice cookers with a rated volume of up to 8 liters and excludes pressure-type and micro-pressure rice cookers that operate at higher cooking pressures.

This standardical framework supports manufacturers, test laboratories, and regulatory bodies by defining key performance characteristics that are relevant to the end user. Note that while it outlines measurement methods, it does not specify performance requirements or safety regulations, the latter being addressed separately under IEC 60335-2-15.

Key Topics

IEC 63399:2024 covers various important aspects of rice cooker performance measurement, including:

• Cooking Inner Pot Evaluation

  • Volume measurement of the inner pot
  • Abrasion resistance of inner pot coatings
  • Corrosion resistance of inner pot coatings

• Cooking Control Performance

  • Cooking uniformity to assess evenness of rice cooking
  • Moisture deviation measurement to evaluate moisture content consistency
  • Burnt rice detection levels to classify the degree of rice scorching

• Temperature Retention

  • Assessment of temperature maintenance during the keep-warm cycle

• Energy Efficiency and Power Consumption

  • Detailed testing for energy use under various operating states:
    • Energy efficiency during cooking control
    • Power consumption in standby mode
    • Power usage during reservation and keep-warm states

• Performance under Low-Voltage Supply

  • Ensures rice cookers deliver consistent performance even with voltage fluctuations

• Testing Conditions and Instrumentation

  • Specifies controlled test environment parameters such as voltage variation limits, test voltage, frequency, and conditioning prior to testing.
  • Defines requirements for measurement instruments to ensure accuracy and repeatability.

Applications

IEC 63399:2024 is designed to serve multiple practical applications:

• Manufacturers can implement these measurement methods to benchmark the performance of their rice cookers, ensuring consistency in product quality and providing reliable data for marketing claims.
• Testing Laboratories benefit from standardized measurement procedures that enable accurate and unbiased evaluation of rice cookers against user-relevant performance indicators.
• Regulatory Authorities may reference this standard to support certification programs and encourage uniform product assessment.
• Consumers indirectly benefit as the standard promotes transparency and helps to foster improvements in rice cooker design, durability, energy efficiency, and cooking quality.
• Retailers and Distributors can use performance data generated by this standard to inform customers and enhance confidence in product offerings.

Related Standards

IEC 63399:2024 is closely connected with other IEC standards to provide comprehensive regulatory coverage in the household electrical appliance domain:

• IEC 60335-2-15
  Covers the safety requirements for household and similar electrical appliances, including rice cookers. While IEC 63399 focuses on performance measurement, IEC 60335-2-15 ensures safe operation and user protection.

• Other IEC Standards on Small Household Appliances
  Standards prepared by IEC technical committee 59 support performance and safety criteria for a wide range of household devices, providing harmonization across product categories.

• International Electrotechnical Vocabulary (IEV)
  Helps with terminology consistency when interpreting and implementing IEC 63399 and related standards.

---

Adoption of IEC 63399:2024 supports the harmonization of testing and performance evaluation, encouraging innovation and high quality in the growing market of electrical rice cookers. By applying its standardized methods, stakeholders can achieve greater transparency and comparability, ultimately enhancing user satisfaction and trust in rice cooker products worldwide.

Standards Content (Sample)

IEC 63399 ®
Edition 1.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical rice cookers – Methods for measuring the
performance
Cuiseurs à riz électrodomestiques et analogues – Méthodes de mesure de
l'aptitude à la fonction
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IEC 63399 ®
Edition 1.0 2024-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Household and similar electrical rice cookers – Methods for measuring the

performance
Cuiseurs à riz électrodomestiques et analogues – Méthodes de mesure de

l'aptitude à la fonction
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 97.040.50  ISBN 978-2-8322-9796-4

– 2 – IEC 63399:2024 © IEC 2024
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 List of measurements and tests . 7
5 General conditions for measurements . 8
5.1 General . 8
5.2 Test environment . 8
5.3 Limits of voltage variation . 8
5.4 Test voltage . 8
5.5 Test frequency . 8
5.6 Test electrical supply system . 8
5.7 Conditioning prior to the test . 8
5.8 Requirements for measurement instruments . 8
6 Measurements . 9
6.1 Cooking inner pot . 9
6.1.1 Volume of inner pot of rice cooker . 9
6.1.2 Endurance of the inner pot coatings – Abrasion resistance . 10
6.1.3 Endurance of the inner pot coatings – Corrosion resistance . 11
6.2 Cooking control . 12
6.2.1 Cooking uniformity . 12
6.2.2 Moisture deviation . 15
6.2.3 Burnt levels of the cooked rice . 17
6.3 Temperature retention during keep-warm state . 18
6.4 Energy efficiency . 18
6.4.1 Control setting . 18
6.4.2 Measurement of energy efficiency . 19
6.5 Power consumption . 19
6.5.1 Power consumption in stand-by mode . 19
6.5.2 Power consumption in reservation state . 19
6.5.3 Power consumption during keep-warm state . 20
6.6 Performance in low-voltage supply . 20
Annex A (informative) Physical characteristics of cooked rice . 21
A.1 Expansion rate . 21
A.2 Hardness and adhesiveness of cooked rice . 22
Annex B (informative) Different types of "white point" in the standard for reference of
the engineer for comparison . 24
Annex C (normative) Different burnt levels of the cooked rice . 27
Bibliography . 34

Figure 1 – Drawing of top edge of inner pot with filled water . 10
Figure 2 – Coating abrasion resistance test set up . 11
Figure 3 – Cooked rice divided into 12 equal parts . 12
Figure 4 – Evaluation procedures . 15
Figure 5 – Sampling positions of the rice for moisture content . 16

Figure 6 – Temperature change over time during keep-warm state . 18
Figure A.1 – Texture characteristics curve from measurement of texture analyser . 23
Figure B.1 – Reference pictures of "white points" . 26
Figure C.1 – Example of Level 1 of burnt condition . 27
Figure C.2 – Example of Level 2 of burnt condition . 27
Figure C.3 – Example of Level 3 of burnt condition . 28
Figure C.4 – Example of Level 4 of burnt condition . 28
Figure C.5 – Example of Level 5 of burnt condition . 29
Figure C.6 – Example of Level 6 of burnt condition . 29
Figure C.7 – Example of Level 7 of burnt condition . 30
Figure C.8 – Example of Level 8 of burnt condition . 30
Figure C.9 – Example of Level 9 of burnt condition . 31
Figure C.10 – Example of Level 10 of burnt condition . 31
Figure C.11 – Example of Level 11 of burnt condition . 32
Figure C.12 – Example of Level 12 of burnt condition . 32
Figure C.13 – Example of Level 13 of burnt condition . 33

Table A.1 – Texture analyser measuring parameters . 22

– 4 – IEC 63399:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HOUSEHOLD AND SIMILAR ELECTRICAL RICE COOKERS –
METHODS FOR MEASURING THE PERFORMANCE

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
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IEC 63399 has been prepared by subcommittee 59L: Small household appliances, of IEC
technical committee 59: Performance of household and similar electrical appliances. It is an
International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
59L/269/FDIS 59L/273/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
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• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
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of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 63399:2024 © IEC 2024
HOUSEHOLD AND SIMILAR ELECTRICAL RICE COOKERS –
METHODS FOR MEASURING THE PERFORMANCE

1 Scope
This document applies to household and similar electrical rice cookers.
This document defines the main performance characteristics that are of interest to the user and
specifies methods for measuring these characteristics.
This document does not specify the requirements for performance.
This document does not apply to the pressure type rice cooker or the micro-pressure rice
cooker.
This document does not apply to rice cookers with the rated volume of rice cooker larger
than 8 L.
NOTE 1 The pressure type rice cooker refers to a rice cooker that cooks at a pressure more than 40 kPa.
NOTE 2 The micro-pressure rice cooker refers to a rice cooker that cooks at a pressure larger than 10 kPa but
not more than 40 kPa.
NOTE 3 This document does not deal with safety requirements (covered in IEC 60335-2-15).
NOTE 4 Some of the tests which are specified in this document are not considered to be reproducible since the
results can vary between laboratories. They are therefore intended for comparative testing purposes only.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 62301, Household electrical appliances – Measurement of standby power
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
rice cooker
appliance for cooking rice that is placed in a detachable inner pot, the inner pot being placed
within the appliance when cooking

3.2
rated volume of rice cooker
total volume of the inner pot of a rice cooker declared by the manufacturer
3.3
stand-by mode
any product modes where the energy using product is connected to a mains power source and
offers one or more of the following user oriented or protective functions which usually persist
– to facilitate the activation of other modes (including activation or deactivation of active
mode) by remote switch (including remote control), internal sensor, timer;
– continuous function: information or status displays including clocks;
– continuous function: sensor-based functions
Note 1 to entry: Optional definition: a power on state in which the rice cooker is ready for interaction with the user,
before confirming to heat up or cook.
[SOURCE: IEC 62301:2011, 3.6, modified – Note was replaced.]
3.4
reservation state
power on state in which the rice cooker counts the timing and starts to work once a period of
time set by the user in advance elapses
3.5
keep-warm state
power on state in which the rice cooker keeps a low electric heating power to maintain the
warm temperature of the cooked rice
3.6
expansion rate
ratio of the volume increase of the cooked rice to the volume of the raw rice
Note 1 to entry: The raw rice becomes bigger sized after cooked.
4 List of measurements and tests
– Volume of inner pot of rice cooker (6.1.1);
– Endurance of the inner pot coatings – Abrasion resistance (6.1.2);
– Endurance of the inner pot coatings – Corrosion resistance (6.1.3);
– Cooking uniformity (6.2.1);
– Moisture deviation (6.2.2);
– Burnt levels of the cooked rice (6.2.3);
– Temperature retention during keep-warm state (6.3);
– Energy efficiency (6.4);
– Power consumption in stand-by mode (6.5.1);
– Power consumption in reservation state (6.5.2);
– Power consumption during keep-warm state (6.5.3);
– Performance in low-voltage supply (6.6).
Evaluation of physical characteristics of the cooked rice is provided in informative Annex A.

– 8 – IEC 63399:2024 © IEC 2024
5 General conditions for measurements
5.1 General
Unless otherwise specified, the tests are carried out under the conditions of 5.1 to 5.8.
If the instructions for use of the rice cooker recommend the setting, then that setting shall be
used.
If the instructions for use of the rice cooker do not recommend the setting, the default function
setting shall be used.
Unless otherwise specified, the water used in the test is the drinking water with the ambient
temperature.
NOTE The drinking water refers to the water which is used for cooking in the area of the lab.
5.2 Test environment
The tests are carried out in a draught-free location at an ambient temperature of 20 °C ± 5 °C.
Ambient temperature is maintained at 23 °C ± 2 °C for temperature-sensitive cooking and
warming performance test.
The relative humidity is maintained at 45 % ~ 75 %.
The air pressure for the test shall be 98 kPa ~ 102 kPa.
5.3 Limits of voltage variation
During the tests, the variation in the voltage shall not exceed ±1 % of the test voltage.
5.4 Test voltage
Unless otherwise specified, the tests are carried out at a specific voltage within a voltage range
(e.g. 100 V to 240 V) or at the rated voltage or voltages (e.g. 120 V, or 120 V and 240 V).
5.5 Test frequency
The appliances are tested at the rated frequency or within a rated frequency range (e.g. rated
as 50 Hz and 60 Hz, or 50 Hz to 60 Hz).
5.6 Test electrical supply system
Total harmonic distortion of the test electrical supply system shall be less than 5 %.
5.7 Conditioning prior to the test
The rice cooker including the inner pot, the outer pot and the water for the test shall remain
6 h under the ambient temperature.
The control setting of the rice cooker shall be set to the function of rice-cooking.
5.8 Requirements for measurement instruments
The accuracy of voltmeter and wattmeter shall be ±0,5 %.
The resolution of the instrument used to measure temperature shall be 0,1 °C.

The accuracy of weighing apparatus of full scale shall be ±0,1 % and its resolution shall be less
than 1 g.
The accuracy of measurement of time shall be ± 5 s.
The wire diameter of thermocouple shall not be larger than 0,3 mm.
6 Measurements
6.1 Cooking inner pot
6.1.1 Volume of inner pot of rice cooker
a) The mass of the inner pot is weighed and recorded as m .
b) The inner pot is positioned horizontally, and filled with the water until the level of water
reaches the top edge of the inner pot. See Figure 1. The total weight of the inner pot and
the water is measured and recorded as m. If the top surface of water is affected by the
surface tension, the water is levelled with a surfactant.
NOTE Any commercially available rinsing agent can be used as the surfactant.
c) The actual volume of the inner pot is calculated by Formula (1). The deviation from the rated
volume of rice cooker is calculated by Formula (2).
mm−
V =
(1)
c
ρ
where
V is the actual volume of the inner pot, in L;
c
m is the total mass of the inner pot and the water filled in it, in kg;
m is the mass of the inner pot, in kg;
ρ is the density of water, taken as 1 kg/L.
V
c
δ ×100%
(2)
V
e
where
δ is the volume deviation of the inner pot, in %, accurate to two decimal place;
V is the rated volume of rice cooker, in L.
e
=
– 10 – IEC 63399:2024 © IEC 2024

Figure 1 – Drawing of top edge of inner pot with filled water
6.1.2 Endurance of the inner pot coatings – Abrasion resistance
The test set up is shown in Figure 2.
A clean inner pot of a rice cooker is fixed on the test equipment as shown in Figure 2. The size
of the jig to which the scouring pad is attached is 60 mm ± 3 mm in length and 20 mm ± 3 mm
in width. The scouring pad with dimensions of 70 mm ± 5 mm length and 30 mm ± 5 mm width,
which has been thoroughly soaked with water, is placed at the centre of the bottom of the inner
pot. A downward force of 15 N is applied on the scouring pad. The pad is moved in a
reciprocating manner with the speed of 30 cycles/min. The movement of the pad is started from
the middle of the inner pot. One cycle includes 4 strokes, including the movements from the
middle to the left end, from the left end back to the middle, from the middle to the right end and
from the right end back to the middle. The distance of one stroke is 50 mm.
NOTE For the inner pot with small volume (less than 3 L), the stroke distance can be accordingly adjusted.
The coating surface of the inner pot is inspected at the interval of 250 cycles by means of a
10-multiple magnifying glass. At the same interval, the scouring pad is thoroughly soaked with
water. The scouring pad is replaced with a new one at a rate of 2 500 cycles. The test is
terminated when a trace of the exposed substrate with a width of more than 1 mm is detected
on the coating surface of the inner pot.
Record the total number of cycles before termination of the test.
___________
Scotch-Brite™ 7447B, 7447 and 7447C are examples of a suitable scouring pad available commercially. This
information is given for the convenience of users of this document and does not constitute an endorsement by
IEC.
Key
1 driving device
2 fixture
3 scouring pad
4 inner pot of rice cooker
5 fixture
6 weight for applying 15 N downwards force
Figure 2 – Coating abrasion resistance test set up
6.1.3 Endurance of the inner pot coatings – Corrosion resistance
The inner pot is filled with 5 % saline water (obtained by mixing pure water and sodium chloride)
to the maximum level as marked or specified in the instructions for use of the rice cooker. The
inner pot is placed in correct position of the rice cooker and covered with its lid. Switch on the
cooking function to heat the water to boil and keep cooking function for 8 h. The inner pot is
refilled with the saline water every two hours to keep the water level at the starting level. At the
end of 8 h, the rice cooker is transferred from cooking function to keep-warm state and kept
in warming preservation condition for 16 h.
The combination with 8 h heating and 16 h warming preservation is considered as one test
cycle. 8 h heating can include several cooking cycles. When one cooking cycle is ended,
another cooking cycle is manually restarted. This process is repeated until the total 8 h heating
period is reached.
The test is carried out for 4 test cycles and the coating is inspected after each test cycle. A
10-multiple magnifying glass is used for inspection.
Inspection result is recorded. If a trace of corrosion is detected, the size of corrosion is
measured and recorded.
– 12 – IEC 63399:2024 © IEC 2024
6.2 Cooking control
6.2.1 Cooking uniformity
6.2.1.1 Preparing the test sample of cooked rice
a) The rice used for the test is obtained from the normal consumer market, which was produced
not more than 12 months.
NOTE Production means milling and polishing operation.
b) According to the instructions for use supplied by the manufacturer, the inner pot is filled with
the medium amount of rice and the corresponding water, and the cooking function is
switched on.
c) At the end of the cooking cycle, turn off the power supply and leave it for 15 minutes. Then
turn the inner pot over and remove all the cooked rice onto the table while maintaining the
cylindrical shape of the inner pot.
d) The whole cooked rice is divided into 12 equal parts, i.e. 12 cooked rice samples, as shown
in Figure 3.
Figure 3 – Cooked rice divided into 12 equal parts

6.2.1.2 Evaluation
a) Take 10 grains of cooked rice with a tweezer evenly from each of the 12 cooked rice
samples.
NOTE 1 Burnt rice grains that cannot be crushed are excluded from the rice grains to be removed.
b) Arrange 10 cooked rice grains evenly between two pieces of transparent glass plates or PC
plastic plates that provide a good contrast to the cooked rice. The plate shave dimensions
of 150 mm × 150 mm × 4 mm. See Figure 4a).
c) Apply a force of (13 ± 2) N vertically downward to the midpoint of the upper plate for 2 s to
crush the rice grains as much as possible, see Figure 4b). If there are rice grains which are
not crushed fully, apply a force of (13 ± 2) N vertically downward to the position of each
uncrushed grain until it is crushed to as much as possible to allow inspection for "white
point" in the grain, see Figure 4c).
NOTE 2 The force of (13 ± 2) N can be applied with a force gauge.
d) Check each crushed rice grain if any "white point" appears, see Figure 4d) and record the
number of the crushed rice grains with "white point" as N .
e) Repeat above steps a) to d) with the rest 11 cooked rice samples. Record the corresponding
number of the crushed rice grain with "white point" as N , N …N respectively.
2 3 12
Evaluation procedures are shown in Figure 4.

a) Arrangement of 10 grains cooked rice of the sample

– 14 – IEC 63399:2024 © IEC 2024

b) Applying a force of (13 ± 2) N vertically downward to the midpoint of the upper plate

c) Applying a force of (13 ± 2) N vertically downward to the position of each uncrushed grain

d) Observing the rice grain appearing "white point"

Figure 4 – Evaluation procedures
The rate of the cooked rice with "white point" in the cooked rice sample is calculated as follows:
N
∑ i
i=1
(3)
R ×100%
10×12
where
R is the rate of the cooked rice with "white point" in the cooked rice;
th
N is the number of the cooked rice grains with "white point" in the i part of the cooked
i
rice;
10 × 12 is the total number of cooked rice grains taken for evaluation.
NOTE 3 Annex B provides the pictures to show different types of "white point" in the standard for convenience of
the engineer for comparison.
6.2.2 Moisture deviation
6.2.2.1 Instruments and equipment
The following instruments and equipment are used in this test:
– electronic scale (the resolution: 0,2 g);
– electronic balance (the resolution: 0,000 1 g);
– blast air oven (operating temperature: from 100 °C to 200 °C or more);
– glass desiccator (filled with effective desiccant);
– aluminium flat weighing box with the lid.
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– 16 – IEC 63399:2024 © IEC 2024
6.2.2.2 Test procedure
a) In accordance with the instructions for use of the rice cooker, the maximum amount of rice
is cooked under a certain cooking setting (if necessary, the test can be carried out
respectively under each cooking setting).
b) During the cooking period, 9 clean aluminium flat weighing boxes are prepared and placed
into the blast air oven with heating at the temperature of 101 °C to 105 °C, with the lid of
the box obliquely standing on the side of the box. After heated for 1 h, the boxes are taken
out, covered with the lids immediately, and placed in the desiccator at the room temperature
for 30 min, then the boxes are removed and weighed with the balance. The drying process
in the desiccator is repeated until the difference of the mass of the box measured between
the successive two times is not more than 2 mg, then this mass value is taken as the
constant weight, recorded as m (i = 1, 2, 3,……, 9).
2i
c) After the cooking cycle is completed, immediately the cover of rice cooker is opened and 9
cooked rice samples, each of which is 5 g ± 2 g, are taken from 9 positions shown in
Figure 5. These rice samples are recorded as rice sample 1, 2, 3,……,9. The process to
prepare the 9 rice samples shall be finished within 2 min.
NOTE 1 As for the sampling positions near the wall and bottom of the inner pot, i.e. point 1, 3, 4, 6, 7, 8, and 9, the
cooked rice which is 10 mm to 20 mm away from the wall and bottom of the inner pot is taken for the samples.
Dimensions in millimetres
Figure 5 – Sampling positions of the rice for moisture content
9 rice samples are placed respectively into the aluminium weighing boxes which are covered
with the lids immediately. The boxes with rice samples are respectively weighed accurately and
'
their masses are correspondingly recorded as m (i = 1, 2, 3,……, 9).
i
9 boxes with rice samples are placed into the blast air oven with heating at the temperature of
101 °C to 105 °C, with the lids being removed and obliquely standing on the side of the
corresponding boxes. After heated for 3 h, the boxes are taken out and covered with the lids
again. Then the boxes are kept in the desiccator at the room temperature for 30 min, and the
boxes are removed and weighed respectively with the balance. The drying process in the
desiccator is repeated until the difference of the mass of each box measured between the
successive two times is not more than 2 mg, then this mass value is taken as the constant
''
weight, recorded as m (i = 1, 2, 3,……,9).
i
NOTE 2 The latter weighing value from the two constant weights of successive two times is taken for the final
calculation.
6.2.2.3 Calculation of moisture deviation
The moisture content of each of the rice samples is calculated by Formula (4).
' ''
mm−
ii
X ×100%
(4)
i
'
mm−
ii2
where
is the moisture content of the ith rice sample, in %;
X
i
'
m is the mass of the ith weighing box and the ith rice sample, in g;
i
''
m is the mass of the ith weighing box and the ith rice sample after drying, in g;
i
m is the mass of the ith weighing box, in g.
2i
When the moisture content is greater than or equal to 1 %, the result retains three significant
figures; when the moisture content is less than 1 %, the result retains two significant figures.
The moisture deviation is calculated by Formula (5).
D X− X
(5)
max min
where
D is the moisture deviation, in %;
X is the maximum value of moisture content among 9 rice samples, in %;
max
X is the minimum value of moisture content among 9 rice samples, in %.
min
6.2.3 Burnt levels of the cooked rice
6.2.3.1 Preparing the test sample
a) The rice used for the test is obtained from normal consumer market, which was produced
not more than 12 months.
NOTE Production means milling and polishing operation.
b) According to the instructions for use supplied by the manufacturer, the inner pot is filled with
the maximum amount of rice and the corresponding water and the cooking function is
switched on.
c) 15 min after the end of cooking cycle, the inner pot is overturned and the cooked rice is
poured onto a table with the bottom of the cooked rice upward.
6.2.3.2 Evaluation
The cooked rice bottom is photoed and compared with the pictures in Annex C.
If 80 % of the bottom area is consistent with one of the levels in Annex C, that level is
considered as the burnt level of the cooked rice.
NOTE Annex C provides different burnt levels of the cooked rice.
=
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– 18 – IEC 63399:2024 © IEC 2024
6.3 Temperature retention during keep-warm state
a) The rice used for the test is obtained from normal consumer market, which was produced
not more than 12 months.
NOTE Production means milling and polishing operation.
b) According to the instructions for use supplied by the manufacturer, the inner pot is filled with
the maximum amount of the rice and the corresponding water, and the rice cooker is set in
normal cooking mode.
c) The temperature measuring points of the thermocouple are fixed at the two locations along
the central axis of the inner pot: one is at the height of 10 mm ± 5 mm from the bottom, and
the other is at half the height of the mixture of the rice and the water in the inner pot.
d) The cooking cycle is started.
e) Once the cooking cycle is finished and the rice cooker enters into keep-warm state, the
timing is started and the temperature is measured and recorded. After 5 h of warm
preservation, the test is terminated.
f) A temperature – time curve is plotted. See Figure 6.

Figure 6 – Temperature change over time during keep-warm state
th th
The temperature values are measured at the interval of 1 min from the 4 hour to the 5 hour.
The mean value over the duration of 10 min with the least temperature change is taken as the
temperature during keep-warm state.
6.4 Energy efficiency
6.4.1 Control setting
The rice cooker is tested at normal rice cooking setting. For the multi-functional rice cooker,
the test is carried out at the highest energy-saving setting specified in the instructions. The
default setting is chosen when neither the highest energy-saving setting is specified in the
instructions nor is the normal rice cooking setting indicated.

6.4.2 Measurement of energy efficiency
The inner pot of the rice cooker is filled with the water of 80 % of the rated volume of the rice
cooker. The thermocouple is passed through the lid in the way that does not influence the
normal rice cooking operation. The temperature measuring points of the thermocouple are fixed
at the two locations along the central axis of the inner pot: one is at the height of 10 mm ± 5 mm
from the bottom, and the other is at half the height of the water level in the inner pot. The initial
water temperature is measured as t . The rice cooker is supplied with the rated voltage, and a
watt-hour meter (electricity meter) is connected to measure the power consumption. The
cooking function with the setting specified in 6.4.1 is started to heat the water. When the
temperatures of all measuring points reach 90 °C, the rice cooker is disconnected from the
power supply and the consumed energy is measured and recorded. Because of the thermal
capacity and thermal lag of the heating plate, the water temperature of the measuring point may
still increase even if the rice cooker has been turned off. The water temperature shall be
monitored and the average t of the highest temperatures at the two measurement locations
shall be recorded after the power supply is disconnected.
NOTE For rice cookers heated by means of eddy currents which are induced in the inner pot, or inner pot and lid
by the electromagnetic field of a coil, if the magnetic field has strong influence on the test result, the temperature
can be measured by the stranded platinum resistance thermometer or other equivalent methods.
The energy efficiency is calculated by Formula (6):
1,16××Gt( − t )
(6)
η ×100%
E
where
η is the energy efficiency, accurate to one decimal place;
G is the weight of water in inner pot before the test, in kg;
t is the initial water temperature before the test, in °C, accurate to one decimal place;
is the average of the highest water temperatures at the two measurement locations after
t
the test, in °C, accurate to one decimal place;
E is the energy consumption, in W·h, accurate to two decimal place;
1,16 is the specific heat capacity of water, in W·h/kg·°C.
6.5 Power consumption
6.5.1 Power consumption in stand-by mode
The power consumption of the rice cooker in stand-by mode is measured in accordance with
IEC 62301.
6.5.2 Power consumption in reservation state
The inner pot of the rice cooker is filled with the proper amount of the rice and the
corresponding water, as specified in the instructions for use. The rice cooker is set to
reservation state with the maximum reservation time as specified in the instructions.
The power consumption of the rice cooker in reservation state is measured in accordance
with IEC 62301.
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– 20 – IEC 63399:2024 © IEC 2024
6.5.3 Power consumption during keep-warm state
During the test of 6.3, a power meter is connected to the circuit of the rice cooker. Once the
cooking cycle is ended, start to measure and monitor the power consumption in keep-warm
state. The measurement continues for 5 h. The total power consumption is recorded as kW·h.
The power consumption per hour is calculated by dividing the total power consumption by 5 h.
6.6 Performance in low-voltage supply
The rice cooker is supplied at the voltage of −10 % of the rated voltage with the rated frequency.
The test procedures specified in 6.2.1 is repeated except with the voltage specified in this
subclause.
The overflow phenomena of the rice cooker, if any, shall be monitored and recorded during the
test.
The test result is compared with that of 6.2.1.

Annex A
(informative)
Physical characteristics of cooked rice
A.1 Expansion rate
NOTE 1 Since the physical properties required for the rice differ in each country, it is possible to adopt appropriate
equipment and conditions.
The test rice is the selected rice obtained from normal consumer market, which was produced
not more than 12 months.
NOTE 2 Production means milling and polishing operation.
The rice is cooked according to the instructions for use, with the maximum amount of rice and
the corresponding water. The total cooked rice is removed, weighed and recorded as m .
50 g of the cooked rice is taken and filled into a 100 ml measuring cy
...