Detail of GB/T 39891-2021

Introduction of GB/T 39891-2021

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization—Part 1: Rules for the structure and drafting of standardizing documents. This standard was proposed by and is under the jurisdiction of the National Technical Committee of Standardization of Examination Methods for Key Products of Quality Supervision (SAC/TC 374).   Introduction The extended electrical life of circuit-breaker (circuit-breaker class E2) defined in 3.4.113 of GB/T 1984-2014, that is, the electrical endurance of circuit-breaker, is derived from the operation experience of specific high-voltage circuit-breaker and the system protection and maintenance strategy. Moreover, for newly developed circuit-breakers, the electrical endurance can only be verified by laboratory tests. The new maintenance strategy tends to be “maintenance-free circuit-breaker”. For most users, the main concern is to reduce maintenance cost, and the maintenance-free performance of circuit-breaker can be verified by laboratory tests. In order to prevent different users from adopting different electrical endurance test procedures and ensure the consistency of the electrical endurance data of circuit-breakers provided by various manufacturers in the sales process, it is necessary to put forward standardized test procedures. Electrical endurance testing for circuit-breakers above a rated voltage of 52 kV 1 Scope This document specifies the general provisions, test samples, electrical endurance test procedures separated from standard type test, electrical endurance test procedures combined with standard type test, no-load test, wear test and acceptance test of the electrical endurance testing for circuit-breakers of 52 kV and above. This document is applicable to SF6 circuit-breakers class E2 for overhead lines of 52 kV and above. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 1984-2014 High-voltage alternating-current circuit-breakers GB/T 2900.20-2016 Electrotechnical terminology—High-voltage switchgear and controlgear GB/T 7674-2008 Gas-insulated metal-enclosed switchgear for rated voltages of 72.5kV and above GB/T 11022-2011 Common specifications for high-voltage switchgear and controlgear standards 3 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 1984-2014, GB/T 2900.20-2016 and GB/T 11022-2011 as well as the following apply. 3.1 restrike a resumption of non-residual current between the contacts of a mechanical switching device within a quarter of a power frequency period or longer after the arc extinguished during a breaking operation Note: All circuit-breakers in operation have a certain probability of restrike. The level of restrike probability also depends on the operating conditions (such as insulation coordination, annual operation times, user's maintenance plan, etc.). Therefore, in order to classify the restrike performance of circuit-breakers, circuit-breakers class C1 and Class 2 are introduced. [Source: GB/T 2900.20-2016, 9.43, modified] 3.2 circuit-breaker class C1 a circuit-breaker that has a low probability of restrike during capacitive current breaking verified by specified type tests [Source: GB/T 1984-2014, 3.4.114] 3.3 circuit-breaker class C2 a circuit-breaker that has a very low probability of restrike during capacitive current breaking verified by specified type tests [Source: GB/T 1984-2014, 3.4.115] 3.4 circuit-breaker class E2 a circuit-breaker, designed such as not to require maintenance of the breaking parts of the main circuit during its expected operating life, and only little maintenance for other parts (circuit-breaker with extended electrical life) Note 1: Generally used for applications where frequent fault current are switched. Note 2: Little maintenance refers to lubrication, if applicable, changing gas and cleaning external surfaces. [Source: GB/T 1984-2014, 3.4.113, modified] 3.5 rated short-circuit break current the expected maximum short-circuit RMS current at which the circuit-breaker terminal can break under the specified service and performance conditions and also at the specified voltage 3.6 arcing time interval of time between the instant of an arc initiation in the first pole and the instant of the final arc extinction in all poles [Source: GB/T 1984-2014, 3.7.134] 3.7 direct test the test in which the applied voltage, the current and the transient and power-frequency recovery voltages are all obtained from a circuit having a single-power source, which may be a power system, or special alternators as used in short-circuit testing stations, or a combination of both [Source: GB/T 4473-2018, 3.1] 3.8 synthetic test the test in which all of the current, or a major portion of it, is obtained from one source (current circuit), and in which the applied voltage and/or the recovery voltage (transient and power frequency) are obtained wholly or in part from one or more separate sources (voltage circuits) [Source: GB/T 4473-2018, 3.2] 3.9 electrical endurance the limit of cumulative electrical wear that a circuit-breaker can withstand from the breaking current while operating normally under the normal working conditions during the operating life Note: It is also commonly referred to as extended electrical life. 3.10 transient recovery voltage; TRV the recovery voltage observed with obvious transient character across contacts of circuit-breaker after breaking of a short-circuit current and arc extinction Note 1: The transient recovery voltage may be oscillatory or non-oscillatory or a combination of these depending on the characteristics of the circuit and the switching device. It includes the voltage shift of the neutral point of a polyphase circuit. Note 2: The transient recovery voltage in three-phase circuits is, unless otherwise stated, that across the first-pole-to-clear, because this voltage is generally higher than the one that appears across each of the other two poles. Note 3: See 4.102 and Annex F of GB/T 1984-2014 for more details about TRV. [Source: GB/T 2900.20-2016, 9.23, modified] 3.11 power frequency recovery voltage the recovery voltage that appears across contacts of circuit-breaker when the transient voltage phenomena has subsided after breaking of a short-circuit current and arc extinction [Source: GB/T 2900.20-2016, 9.24, modified] 4 General 4.1 Maintenance-free period of test samples The maintenance-free test period is usually assumed to be 25 years. The test procedure given in this document is based on the cumulative electrical wear caused by current breaking in the 25-year operating period. If the user thinks that the overhaul period of the electrical wear parts of the arc extinguishing chamber is longer than 25 years, it would be necessary to formulate a special test procedure. Note: Electrical wear is a phenomenon that metal liquid bridges and arcs will be generated in the contact gap of circuit-breakers during breaking current, which will cause metal transfer, splashing and vaporization of contact materials, thus leading to contact material loss and contact surface deformation. The action of arc will also cause electrical wear for other parts in the arc extinguishing chamber. Such as the nozzle of SF6 arc extinguishing chamber. Electrical wear adversely affects the breaking performance, current flow performance and insulation performance of the breaker. 4.2 Factors to be considered in determining the electrical endurance test procedure Factors to be considered in determining the electrical endurance test procedures include, but are not limited to: ——reliability of test procedure; ——economy of test procedure; ——substitution of test procedure, such as using modified standard type test as test procedure of acceptance test; and ——possibility of combining test procedures, such as combining standard type test and electrical endurance test into one test procedure. Note 1: Although they are different from the actual operating conditions, these approaches can judge the design margin of the expected making and breaking of the product under wear conditions. Note 2: The standard type test refers to the making and breaking tests in accordance with those specified in 6.106~6.111 in GB/T 1984-2014. Note 3: This document shall be used together with GB/T 1984-2014, including the tolerance of test parameters. 4.3 Composition of electrical endurance test Electrical endurance test consists of wear test (see Clause 9) and subsequent acceptance test (see Clause 10). 4.4 Types of electrical endurance test procedures This document recommends two electrical endurance test procedures, namely: a) the electrical endurance test procedure separate from standard type test,see Clause 6. b) the electrical endurance test procedure combined with standard type test, see Clause 7.

Contents of GB/T 39891-2021

Contents Foreword i Introduction ii 1 Scope 2 Normative references 3 Terms and definitions 4 General 4.1 Maintenance-free period of test samples 4.2 Factors to be considered in determining the electrical endurance test procedure 4.3 Composition of electrical endurance test 4.4 Types of electrical endurance test procedures 4.5 Basic principles of electrical endurance test procedures 5 Test sample 5.1 General 5.2 Test sample parameters and structure 5.3 Information of test samples 5.4 Consistency confirmation of test sample drawings and data 6 Electrical endurance test procedure separated from standard type test 6.1 Test sequence and criteria 6.2 Test conditions for electrical endurance test separate from standard type test 7 Electrical endurance test procedure combined with standard type test 7.1 General 7.2 Equivalent number of breaking operations 7.3 Combined test procedure 8 No-load test 8.1 General 8.2 Rated operating sequence 8.3 No-load operation test to verify the consistency of test samples 8.4 No-load operation tests before and after electrical endurance test 9 Wear test 9.1 General 9.2 Test procedures and requirements 10 Acceptance test 10.1 General 10.2 No-load operation test 10.3 T10 test 10.4 L75 test at 60% rated short-circuit break current 10.5 Switching test at line charging current 10.6 Status inspection Annex A (Informative) Making and breaking test methods of circuit-breakers associated with electrical endurance testing A.1 Basic short-circuit test A.2 Short-line fault test A.3 Out-of-step making and breaking tests (OP1 and OP2) A.4 Switching test at line charging current Annex B (Informative) Examples of electrical endurance test of circuit-breakers separated from standard type test B.1 Test sample B.2 Test procedure Reference Figure 1 Connection of three-pole switching device Figure B. 1 Schematic diagram of test sample Figure B. 2 Oscillogram of opening no-load characteristic curve Figure B. 3 Oscillogram of closing no-load characteristic curve Figure B. 4 T10 (T60) test circuit for abrasion resistance Figure B. 5 Oscillogram of T10 test for abrasion resistance Figure B. 6 T10 acceptance test circuit Figure B. 7 Oscillogram of T10 acceptance test Figure B. 8 L75 acceptance test circuit at 60% rated short-circuit break current Figure B. 9 Oscillogram of L75 acceptance test at 60% rated short-circuit break current Figure B. 10 LC1 acceptance test circuit Figure B. 11 Oscillogram of LC1 acceptance test Figure B. 12 Impulse voltage test circuit for status inspection Table 1 Electrical endurance test sequence and criteria separated from standard type test Table 2 Number of breaking happened at 60% rated short-circuit breaking current (M90) Table 3 Test conditions for electrical endurance test separate from standard type test Table 4 Equivalent number of breaking operations Table 5 Combined procedure of electrical endurance test and standard type test of synthetic test for 50 kA circuit-breaker——type test method excluding electrical life Table 6 Combination procedure of electrical endurance test and standard type test for 50 kA circuit-breaker—type test method including electrical life Table 7 Relationship between capacitive voltage coefficient for capacitive current acceptance test in electrical endurance testing program and that for standard test Table B. 1 Record of no-load characteristic test parameters Table B. 2 Record of T10 (T60) abrasion resistance test parameters Table B. 3 Record of T10 acceptance test parameters Table B. 4 Record of TRV parameters of L75 acceptance test at 60% rated short-circuit break current Table B. 5 Record of L75 acceptance test parameters at 60% rated break current Table B. 6 Record of LC1 acceptance test parameters Table B. 7 Record of status inspection parameters using impulse voltage or T10 TRV test