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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 11023-1989 Test guide of SF6 gas tightness for high-voltage switchgear and the following main technical changes have been made with respect to GB/T 11023-1989:
——the clause "Normative references" is added, and subsequent clause numbers are modified (see Clause 2);
——relevant terms and definitions including "gas-filled compartment" and "controlled pressure system for gas" are added (see Clause 3);
——the general of test items is adjusted; the calculation method of permissible leakage rate Fp based on the limit of relative yearly leakage rate Fy is added; the limit of permissible leakage rate is added; the recommended method to obtain accurate volume of measurement is given, and the contents of the Annex A in original standard are moved into this subclause and modified (see 4.1);
——the acceptable ambient temperature is added in the tightness test at normal temperature (see 4.2);
——the contents unrelated to the tightness test in high- and low-temperature tightness tests are adjusted (see 4.3);
——5.1.4 "Leakage detecting by infrared imaging" and 5.1.5 "Leakage detecting with helium mass spectrometer" are added in the qualitative leakage detecting (see 5.1);
——the sequence of the four test methods in quantitative leakage detecting is adjusted; the calculation equation is adjusted to the calculation method using tracer gas; the standing time after air inflation and the time after bandaging are uniformly specified (see 5.2);
——in the buckle cover method, the relationship between the time between replenishments, T, and the relative yearly leakage rate, Fy, is added (see 5.2.2);
——in the pressure drop method, the calculation method of relative daily leakage rate, Fd, and number of replenishments per day, N, for the controlled pressure system for gas is added (see 5.2.4);
——relevant examples are added in Annexes A and B (see Annexes A and B);
——Annex C "Principle and spectrum examples of infrared imaging sniffing" is added (see Annex C).
This standard was proposed by China Electrical Equipment Industrial Association.
This standard is under the jurisdiction of the National Technical Committee on High-voltage Switch Gear of Standardization Administration of China (SAC/TC 65).
The previous edition of this standard is as follows:
——GB/T 11023-1989.
Test method of SF6 gas tightness for high-voltage switchgear
1 Scope
This standard specifies the terms and definitions, test items and test methods of SF6 gas tightness for high-voltage switchgear.
The test method specified in this standard is used to determine the relative yearly leakage rate of switchgear/compartment.
This standard is applicable to the test of gas tightness for high-voltage switchgear with SF6 gas as insulation and/or arc-extinguishing medium.
Note: This standard may serve as a reference for the test of gas tightness for high-voltage switchgear with other gases as operation, insulation and/or arc-extinguishing medium or other electrical equipment (such as SF6 current transformer, etc.)
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.
GB/T 11022-2011 Common specifications for high-voltage switchgear and controlgear standards
GB/T 15823-2009 Non-destructive testing - Test methods for helium leak testing
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 11022-2011 and the following apply. For the convenience of application, some terms and definitions specified in GB/T 11022-2011 are listed below.
3.1
gas-filled compartment
compartment of switchgear or controlgear, the gas pressure inside which is maintained by one of the following systems:
a) controlled pressure system;
b) closed pressure system;
c) sealed pressure system
Note: Several gas-filled compartments may be permanently connected into a common gas system (gas tightness assembly).
[GB/T 11022-2011, Definition 3.6.6.1]
3.2
controlled pressure system for gas
space automatically supplied with air from external compressed air source or internal air source
Note 1: Controlled pressure systems including air circuit breaker (gas blast circuit breaker) or air operating mechanism.
Note 2: A space may consist of several permanently connected gas-filled compartments.
[GB/T 11022-2011, Definition 3.6.6.2]
3.3
closed pressure system for gas
space manually connected to an external air source for replenishment where necessary
Note: It is revised from GB/T 11022-2011, Definition 3.6.6.3.
3.4
sealed pressure system for gas
space with no need for further treatment of gas during the scheduled service life
Note 1: The assembly and test of gas sealing pressure system are all carried out in the factory.
Note 2: The expected service life begins when the device is sealed.
Note 3: It is revised from GB/T 11022-2011, Definition 3.6.6.4.
3.5
rated filling pressure pre (or density ρre)
pressure (or density) for insulation and/or switching filled into the gas-filled compartment before being put into operation or automatic replenishment, which may be expressed by relative pressure or absolute pressure when it is converted under standard atmospheric conditions of +20℃ and 101.3kPa
Note: It is revised from GB/T 11022-2011, Definition 3.6.5.1.
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3.6
alarm pressure pae (or density ρa(bǔ)e)
pressure (or density) for insulation and/or switching, which may be expressed by relative pressure or absolute pressure when it is converted under standard atmospheric conditions of +20℃ and 101.3kPa, at which a monitoring signal may be given
Note: It is revised from GB/T 11022-2011, Definition 3.6.5.3.
3.7
minimum functional pressure pme (or density ρme)
pressure (or density) for insulation and/or switching, which may be expressed by relative pressure or absolute pressure when it is converted under standard atmospheric conditions of +20℃ and 101.3kPa, when the pressure is greater than or equal to such pressure, the switchgear and controlgear will maintain their rated characteristics
Note: It is revised from GB/T 11022-2011, Definition 3.6.5.5.
3.8
absolute leakage rate
F
total amount of leaked gas per unit time
Note 1: It is expressed in Pa·m3/s.
Note: It is revised from GB/T 11022-2011, Definition 3.6.6.5.
3.9
permissible leakage rate
Fp
maximum permissible absolute leakage rate for parts, components or subassemblies, or the maximum permissible absolute leakage rate for parts, components or subassemblies connected to a pressure system using tightness coordination chart (TC) as specified by the manufacturer
Note: It is expressed in Pa·m3/s.
[GB/T 11022-2011, Definition in 3.6.6.6]
3.10
relative leakage rate
Frel
absolute leakage rate relative to the total amount of gas in the system filled with rated filling pressure (or density)
Note 1: It is expressed in yearly or daily percentage.
Note 2: In general, Fy is used to express the relative yearly leakage rate, and Fd is used to express the relative daily leakage rate.
Note 3: It is revised from GB/T 11022-2011, Definition 3.6.6.7.
3.11
time between replenishments
T
time interval between two replenishments performed manually when the pressure (or density) drops to the alarm value, thus compensating the absolute leakage rate F
Note 1: This value is applicable to closed pressure system.
Note 2: It is revised from GB/T 11022-2011, Definition 3.6.6.8.
3.12
number of replenishments per day
N
number of replenishments to compensate the absolute leakage rate F
Note: This value is applicable to controlled pressure system.
[GB/T 11022-2011, Definition 3.6.6.9]
3.13
pressure drop
Δp
pressure decrease caused by absolute leakage rate F within a given time when there is no replenishment
[GB/T 11022-2011, Definition 3.6.6.10]
3.14
leakage detecting
means of detecting gas leakage point and concentration of leaked gas
Note: It includes sniffing and cumulative leakage measurement.
3.15
sniffing
act of locating the leakage points by slowly moving the probe of leak detector around the gas-filled compartment, or using other imaging instruments
Note 1: Commonly used imaging sniffing methods include infrared imaging sniffing method and laser imaging sniffing method, etc.
Note 2: It is revised from GB/T 11022-2011, Definition 3.6.6.13.
3.16
cumulative leakage measurement
measurement for determining the leakage rate by taking all air leaks of a given final assembly into account
Note: It is revised from GB/T 11022-2011, Definition 3.6.6.12.
3.17
tightness coordination chart
TC
detection data provided by the manufacturer and used in testing parts, components or subassemblies, which explain the relationship between the tightness of the whole system and the tightness of each part, component or subassembly
[GB/T 11022-2011, Definition 3.6.6.11]
3.18
the buckle cover method
method for calculating and determining the relative leakage rate by placing the test specimen in a closed plastic or metal cover and then determining the concentration of tracer gas in the cover after a certain period of time
3.19
the partial bandaging method
method for calculating and determining the relative leakage rate by bandaging part of the test specimen with plastic film and then determining the concentration of tracer gas in the bandaging cavity after a certain period of time
3.20
the pressure drop method
method for calculating the relative leakage rate by determining the pressure drop of switchgear/compartment within a certain time interval
3.21
the bottle hanging method
method for calculating and determining the relative leakage rate by connecting the leakage detecting hole of test specimen and the hanging bottle by a flexible rubber hose and then determining the concentration of tracer gas in the bottle after a certain period of time
3.22
volume of measurement
Vm
volume between the closed cover for leakage collection and the specimen
Note 1: The concentration of tracer gas in such volume is very low, and the cover generally does not need to be tightly sealed.
Note 2: It is used for the buckle cover method and the partial bandaging method.
Note 3: It is revised from GB/T 2423.23-2013, Definition 3.9.
4 Test items
4.1 General
The purpose of tightness test is to prove that the absolute leakage rate F does not exceed the specified value of the permissible leakage rate Fp at an ambient temperature of 20℃, or to determine that the relative yearly leakage rate meets the requirements of relevant standards or product specifications.
Based on the limit of relative yearly leakage rate Fy (see GB/T 11022-2011, 5.15.3), the permissible leakage rate Fp (Pa·m3/s) at an ambient air temperature of 20℃ is calculated as shown in Equation (1):
(1)
Where,
V——the volume of gas tightness system for test specimen, m3;
pre——the rated filling pressure (relative pressure) at an ambient air temperature of 20℃, Pa.
If the leakage rate falls back to a value that does not exceed the permissible leakage rate Fp when the ambient air temperature returns to 20℃, the leakage rate will increase at the permissible ultimate temperature (if such test is required by relevant standards). The temporarily increased leakage rate shall not exceed the value specified in Table 1.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test items
4.1 General
4.2 Tightness test at room temperature
4.3 High- and low-temperature tightness tests
5 Test methods
5.1 Qualitative leakage detecting
5.2 Quantitative leakage detecting
Annex A (Informative) Tightness (information, example and guidance instruction)
Annex B (Informative) Examples for quantitative leakage detecting
Annex C (Informative) Principle and spectrum examples of infrared imaging sniffing
Bibliography
