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61(2020Web/ahG50)120

December 2020

INTERNATIONAL ELECTROTECHNICAL COMMISSION

TECHNICAL COMMITTEE NO. 61: SAFETY OFHOUSEHOLD AND SIMILAR ELECTRICAL APPLIANCES

Report to TC 61 from ahG 50Safety of household and similar use appliances working under plateau conditions

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1. Background

In the minutes of Shanghai meeting of IEC/TC61, a decision was formed as below:

There was support to form an ad hoc group to collect data and research globally, including that participation is being sought for those regions having plateaus, such as China, Ethiopia, Bolivia and Chile. During the meeting, AU, CN, CH, DE, GB, MX, NZ, and ZA declared their interest in participating to ad hoc WG. The TC 61 Secretary will circulate a call for experts to solicit additional participation on the new ahG. In addition, Mr. Ma is willing to be convenor and will liaise with the National Committees of IEC Affiliate countries: Ethiopia, Bolivia and Chile.

The ad-hoc group planned to prepare a report to be discussed in the TC61 meeting of 2020.

2. Summary of activity

After Shanghai meeting, the convenor of ahG 50 organized the members of the working group to research on environmental conditions in high altitude areas, affecting factors of high altitude environment on electrical safety, electrical safety aspects to be considered in high altitude environment, to collect relevant international standards and national standards, and to carry out comparison test between plateau and plain.ahG 50 held two web meeting on 28th October, 2020 and 26th November, 2020 to discuss the research and test results, the participant expert have contributed good comments and suggestion on the discussion.

3. Finding

3.1 Environmental conditions in high altitude areas

The Environmental conditions indicated in table1 could be a reference as environment parameters in high altitude areas.

Table1

SN Environment Parameters Elevation /m0 1 000 2000 3 000 4 000 5 000

1 Air pressure kPa

Minimum 97.0 87.2 77.5 68.0 60.0 52.5maximum 105.6 92.8 81.5 72.2 63.4 55.5

Annual average 101.3 90.0 79.5 70.1 61.7 54.02 Air

temperature maximal

temperature difference

15，25，30

1

®


SN Environment Parameters Elevation /m0 1 000 2000 3 000 4 000 5 000

℃Minimum +5，-5，-15，-25，-40，-45maximum 45/40 45/40 35 30 25 20

Annual average 20 20 15 10 5 03

Relative humidity%

The wettest monthly

average is the largest

(average minimum

temperature℃)

95/90(25)

95/90(25)

95(20)

95(15)

95(10)

95(5 )

The mean monthly

minimum in the driest month

(average maximum

temperature℃)

20（15）

20（15） 15（15）15（

10）15（5 ） 15（0）

4 Absolute humidity g/m3

Annual average 11.0 7.6 5.3 3.7 2.7 1.7Minimum

annual average 3.7 3.2 2.7 2.2 1.7 1.3

5 Maximum direct solar radiation intensity W/m2 1 000 1 000 1 060 1120 1 180 1 250

6 Maximum air draught speed (m／s) 25，30，35，40

7 Maximum temperature of 1m deep soil℃ 30 25 20 20 15 15

3.2 Affecting factors of high altitude environment on electrical safety1) Impact of reduced air pressure or air density

Impact on the electrical clearance; Impact on medium cooling effect (product temperature rise); Impact on arc extinguishing performance of switchgear; Impact on the action performance of electrical parts; Impact on mechanical structure and sealing of products.

2) Impact of temperature variation Glass products and optical equipment rupture; Moving parts stuck or loose; Separation of structure; Electrical property change; Electronic or mechanical failure due to rapid condensation or icing; Surface coating crack.

3) Impact of absolute humidity of air Impact of absolute humidity on external insulation strength

The average absolute humidity decreases with the elevation. When the absolute humidity decreases, the external insulation strength of electrical products decreases, so the humidity correction of discharge voltage and impulse flashover voltage should be considered.

Impact of absolute humidity on motor commutation and carbon brush wear The decrease of absolute humidity increases the commutation spark of commutator motor and the wear rate of motor carbon brush.

4) Impact of the increase of solar irradiance Impact of increased thermal radiation

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The maximum solar irradiance at 5000 meters above sea level is 1.25 times of the corresponding value at low altitude, and thermal radiation heats objects. For outdoor household electrical appliances, the increase of solar thermal radiation will cause greater surface additional temperature rise, reduce the material properties of organic insulation materials, deform materials, and produce mechanical thermal stress.

Impact of increased ultraviolet radiation The increase rate of ultraviolet irradiance with elevation is much larger than that of total solar irradiance, which can reach twice the corresponding value at low altitude when the altitude is 3000 meters. Ultraviolet rays cause accelerated aging of organic insulating materials, which makes air easy to ionize, resulting in lower external insulation strength and discharge voltage.

3.3 Electrical safety aspects need to be considered in high altitude environment through the theoretical research

Table 2SN Items Description

1 Electric clearanceThere’s the possibility that the current electric clearance is not enough for the use under the plateau condition. The correction factor of altitude shall be considered.

2 Partial discharge The initial voltage decreases, accelerating insulation aging and metal corrosion

3 Power-frequency withstand voltage altitude correction factor need to be considered

4 Electromagnetic Compatibility Radio interference caused by corona

5 Temperature rise

The rise of the altitude can cause the difficulty in heat dissipation and cooling effect decline of the components and appliances .The correction factor for the limited value of the temperature rising shall be considered.

6 Seal

The lower air pressure may cause the pressure difference increase between inside and outside the cavity structure .So it may be considered to adjust the pressure in the sealed cavity for the products used under plateau.

7 Material

Plateau condition can cause the accelerated ageing of material, the intense properties of ultraviolet resistance, heat radiation resistance, cold resistance, temperature difference resistance for the material shall be considered.

3.4 The international/national level standards collected and referred

Table 3International/National level Standard Number Title of Standard

IEC IEC 60721 Series Classification of environmental conditions

IEC IEC 60068 Series Environmental testing

CN GB/T 14092.3-2009 Environmental condition for machinery products - High altitude

CN GB/T 14597-2010 Environmental climatic conditions appearing in different altitudes for electrical products

CN GB/T 19608.3-2004 Classification of specific environmental condition--Part

3


3: PlateauCN GB/T 20625-2006 Special environmental condition - Terminology

CN GB/T 20626 Series Specific environmental condition - Electric and electronic products for plateau

CN GB/T 20643 Series Special environmental condition - Environmental test method

CN GB/T 20644 Series Special environmental condition - Guidance for choosing

CN GB/T 20645-2006 Specific environmental condition - Technical requirements of low-voltage apparatuses for plateau

3.5 Round robin test between plateau and plain

3.5.1 First Round Test

1) Test places and conditions

City Place Elevation Ambient temperature

Atmospheric pressure

Beijing China Household Electric Appliance Research Institute

43.5m 23.0℃ 100.5kPa

Xining Qinghai province product quality supervision inspection office

2261m 22.5℃ 77.4kPa

2) Samples

Sample Photo

Vacuum Cleaner (Motor-operated)

Induction Cooker (Motor-operated)

4


Electric Grill (Heating)

Room heater (Combined)

Hair Dryer (Combined)

3) Instrument

Name Type Factory Photo

Digital power meter 8775A1

Qingdao Qingzhi

Instrument Co., Ltd

5


Fluke 2638A Hydra Series III Data Acquisition

Unit

2638A FLULK

Leakage current meter AN9620X Ai nuo

Withstanding voltage tester TOS5301 KIKUSUI

4) Test itemsa. Power input and currentb. Heatingc. Leakage current and electric strength at operating temperatured. Clearances, creepage distances

5) Test data and analysis

a. Power input

Product Sample No. Place Rated power(W)

Measured power(W) Deviation

Vacuum Cleaner

No.1 Beijing 1100 1086.6 -1.22%Xining 1100 1041.3 -5.34%


Induction Cooker No.1 Beijing 2100 1957.8 -6.77%

Xining 2100 1933.7 -7.92%No.2 Beijing 2100 1998.2 -4.85%

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Xining 2100 1975.1 -5.95%

Electric GrillNo.1 Beijing 1600 1551.4 -3.04%

Xining 1600 1551.2 -3.05%


Room heaterNo.1 Beijing 1500 1501.5 0.10%

Xining 1500 1355.5 -9.63%

No.2 Beijing 1500 1587.2 5.81%Xining 1500 1413.9 -5.74%

Hair DryerNo.1 Beijing 2000 1835.6 -8.22%

Xining 2000 1838.8 -8.06%


The analysis results are as follows: 1) There are obvious differences between the power input data of vacuum cleaner and room heater, and the test data in Beijing laboratory is larger than that in Xining laboratory, which decreases proportionally and has obvious trend. (Yellow highlight in the table) 2) There is no obvious change in the power input of induction cooker, electric grill and hair dryer.

b. Heating

Product Sample No. PlaceTemperature rise

Power cord (k)

Switches (k)

Surface of enclosure (k)

Back shell surface (k)

Vacuum Cleaner

No.1Beijing 10.65 10.31 14.22 26.04

Xining 9.10 17.30 11.80 29.30

No.2Beijing 13.91 13.48 16.05 24.82

Xining 9.00 19.38 14.00 27.00

Induction Cooker

No.1Beijing 10.59 7.66 34.21 26.74

Xining 7.20 13.31 34.41 26.44

No.2Beijing 11.18 11.40 36.50 26.30

Xining 8.00 14.70 42.10 26.80

Electric Grill

No.1Beijing 11.50 45.40 10.36 24.23

Xining 1.40 47.01 6.30 24.50

No.2Beijing 12.47 45.01 12.84 27.87

Xining 2.30 43.30 8.00 25.60

Room heater

No.1Beijing 5.26 21.16 16.36 113.06

Xining 4.40 20.40 21.80 132.20

No.2Beijing 6.10 24.06 16.52 115.50

Xining 4.90 20.20 18.10 138.70

Hair Dryer

No.1Beijing 6.89 6.70 10.32 41.31

Xining 6.60 7.30 13.80 49.10

No.2Beijing 9.47 8.12 8.99 39.40

Xining 6.40 7.00 13.70 48.20

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The analysis results are as follows: 1) There are some differences in the test data of room temperature rise between Beijing and Xining, but there is no certain rule to follow; 2) The temperature rise of the power cord of all samples decreased, and the temperature rise of the power cord of the electric grill decreased most obviously, about 10K; (Yellow highlight in the table) 3) For some points with higher temperature rise, the temperature rise in Xining laboratory is higher than that in Beijing laboratory. For example, the grid temperature rise of room heater is about 110K in Beijing and about 130K in Xining, and the difference between the two temperatures is 20 K; The temperature rise of air outlet surface of hair dryer is about 40K in Beijing and 50K in Xining, and the difference between the two temperatures is 10K. (Blue highlight in the table).

c. Leakage protection

Product Sample No.

Place of testing

Leakage currentNumerical value (mA) Position

Vacuum Cleaner

No.1Beijing 0.0005 L pole and metal foil on the

surface of rear air outlet

Xining 0.013 L pole and metal foil on the surface of rear air outlet

No.2Beijing 0.010 L pole and metal foil on the

surface of rear air outlet

Xining 0.022 L pole and metal foil on the surface of rear air outlet

Induction Cooker

No.1Beijing 0.019 L pole and metal foil of

control panel

Xining 0.017 L pole and metal foil of control panel

No.2Beijing 0.018 L pole and metal foil of

control panel

Xining 0.016 L pole and metal foil of control panel

Electric Grill

No.1 Beijing 0.040 L pole and metal surfaceXining 0.044 L pole and metal surface


Room heater



Hair DryerNo.1 Beijing 0.0005 L pole and handle metal foil

Xining 0.021 L pole and handle metal foil

No.2 Beijing 0.0005 L pole and handle metal foilXining 0.017 L pole and handle metal foil

The analysis results are as follows: 1) The leakage current test values of vacuum cleaner, room heater and hair dryer are obviously different between Beijing and Xining laboratories, and the leakage current value of Xining laboratory is larger; (Yellow highlight in table)2) The leakage current test values of induction cooker and electric grill have no obvious change.

d. Electric clearance, creepage distances

Product Sample No. Place Creepage distances(mm)

Electric clearance(mm)

Vacuum No.1 Beijing 32.84 32.84

8


CleanerXining 32.82 32.82

No.2 Beijing 32.64 32.64Xining 32.66 32.66

Induction Cooker



Electric Grill



Room heater



Hair DryerNo.1 Beijing —— ——

Xining —— ——

No.2 Beijing —— ——Xining —— ——

The analysis results are as follows: 1) There is no obvious difference in the test data of creepage distance and clearance between Beijing and Xining. 2) Although the creepage distance and clearance distance have no change, the withstand voltage test at the same distance between plateau and plain area should be supplemented to confirm whether the breakdown voltage at the same distance between the two places is the same; 3) Due to the structure of the hair dryer, it can’t be recovered after disassembly, and the creepage distance and clearance were not tested.

6) Conclusion and future workThere are some differences in this test. Next time we should still test power input, heating, leakage current, electric strength, and the withstand voltage test at the same distance between plateau and plain area should be supplemented to confirm whether the breakdown voltage at the same distance between the two places is the same. So we should arrange the second test.

3.5.2 Second Round Test

1) Test places and conditions

City Place Elevation Ambient temperature

Atmospheric pressure

Beijing China Household Electric Appliance Research Institute

43.5m 23.0℃ 100.5kPa

Xining Qinghai province product quality supervision inspection office

2261m 22.0℃ 77.1kPa

2) Samples

Sample Photo

9


AC Motor

Standard sample of leakage current

Standard sample of withstand voltage

3) Instrument

Name Type Factory Photo

10


Digital power meter 8775A1

Qingdao Qingzhi

Instrument Co., Ltd

Fluke 2638A Hydra Series III Data Acquisition

Unit

2638A FLULK

Leakage current meter AN9620X Ai nuo

Withstanding voltage tester TOS5301 KIKUSUI

4) Test itemsa. Power inputb. Heatingc. Leakage currentd. Electric strength

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5) Test data and analysis

a. Power inputProduct No. Place Result(W)

AC motorNo.1 Beijing 17.0

Xining 15.5No.2 Beijing 17.1

Xining 15.2

b. Heating

Product No. PlaceTemperature riseof winding（K）（winding）

Temperature riseof winding surface（K）（ thermocouple ）

AC motorNo.1 Beijing 41.3 31.3

Xining 33.8 26.0


In order to intuitively analyse the temperature rise changes on the surface of the AC motor windings, based on the test data of the No. 2 sample, we drew a temperature graph of cumulative time (Graph 1) and a temperature change graph per unit time (Graph 2).

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 580.0

10.0 20.0 30.0 40.0 50.0 60.0

temperature curve of cumulative time

西宁北京

time ： min

tem

pera

ture：℃

Graph 1

-1.0 0.0 1.0 2.0 3.0 4.0 5.0

temperature change curve per unit time

西宁北京

time： min

tem

pera

ture：℃

Graph 2It can be concluded from the graph：1) There are significant differences in temperature rise between Beijing and Xining, and the

temperature rise tested in Beijing is higher than that in Xining.

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2) It can be seen from Graph 1 that the test result in Beijing is higher than in Xining, and it will take longer for Beijing when the temperature rises to be stable.

3) It can be seen from Graph 2 that at the stage of 5min-15min, the temperature rise per unit time in Beijing is higher than that in Xining.

c. Leakage current

Product No. PlaceLeakage current

Result（mA） Posision

Standard sample of leakage current

No.1Beijing 0.447 L pole and testing portXining 0.445 L pole and testing port

No.2Beijing 0.458 L pole and testing portXining 0.457 L pole and testing port

It can be concluded that there is no significant difference in leakage current between Beijing and Xining.

d. Electric strength

Product PlaceElectric strength

Electric clearance（mm） Breakdown voltage（V）

Standard sample of withstand voltage test

Beijing 0.1 842Xining 650Beijing 0.2 1100Xining 920Beijing 0.5 1908Xining 1607Beijing 1.0 2600Xining 2475

It can be concluded that under the same electrical clearance, the sample is easier to be broken down in Xining than in Beijing.

6) Conclusion and future workFrom the above test data, it can be seen that there are certain differences in the electrical safety test of electrical products in plateau area and plain area, and the future work can be carried out from the following aspects:

Increase the test sample quantities and types(such as heating appliances with a high speed motor) for items with differences (such as power input, heating, breakdown voltage, etc.), making in-depth research on data and theory, and find out the real reasons for the differences in test data between the two places;

According to the reasons of the differences in the test items, we should find out which products may have plateau differences, and confirm the product categories and key research objects of plateau electrical appliances;

It is suggested that the number of comparison laboratories should be increased, and tests should be carried out at altitudes of 0m, 1000m, 2000m, 3000m and 4000m respectively, then we can improve the test data and confirm the influence of altitude differences systematically.

More robin tests shall be conducted in other plateau area worldwide if possible. 4. Recommendations

The ahG50 is about to finish its work, based on the discussion of ahG and the demand of industry and certification, it suggests that a new working group should be established and its main task is to

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continue research on the safety of household and similar use appliances working under plateau conditions, and to submit the proposals of IEC 60335 series standards to TC61.

Dejun MA

ahG 50 Convener

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Annex A

ahG 50 Members

ConvenorMr Dejun Ma China

Members

Mr Geoffrey William Booth Austrilia

Mr Jesús María Calzada Simón Spain

Ms Lizhen Guo China

Mr Nicholas Trevor Jones United Kingdom

Mr Thabo Isaac Mabena South Africa

Mr Bruno Reiter Germany

Mr Alan Sellers United Kingdom

Mr Salvo Stella Italy

Mr Meng Wu China

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