JB/T 8314-2025 Test guide for tap-changers
1 Scope
This document specifies the classification of tap-changer tests, as well as the items and procedures for routine tests, type tests and special tests.
This document is applicable to tests for oil-immersed and gas-insulated on-load tap-changers, off-circuit tap-changers and their motor drives and controllers. Tests for on-load tap-changers with reactance transition and other types of tap-changers shall be applied by reference.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions 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 4208 Degrees of protection provided by enclosure (IP code)
GB/T 10230.1 Tap-changers - Part 1: Performance requirements and test methods
3 Terms and definitions
No terms and definitions are defined in this document.
4 Test classification
4.1 Type test
A type test is a test that comprehensively assesses product performance in accordance with the provisions of GB/T 10230.1, including the full set of type tests conducted during new product finalization, and all or part of the tests conducted when major modifications are made to the design, process or key raw materials. Type tests shall be carried out on products that have passed routine tests.
For combined on-load tap-changers, type tests for the diverter switch and the tap selector may be conducted separately, and different test items may be assessed on multiple prototypes.
4.2 Routine test
A routine test is a test conducted on each product before delivery, with the purpose of ensuring the performance reliability of each product. Tests shall generally be conducted on the complete product after final assembly.
4.3 Special test
A test conducted to verify a specific performance of the product as agreed between the user and the manufacturer.
5 Tests for on-load tap-changers
5.1 Type test
5.1.1 General
There are two structural types of on-load tap-changers. One is the combined on-load tap-changer composed of an independent tap selector and an independent diverter switch. The other is the selector switch integrating the functions of both the tap selector and the diverter switch, also known as the integrated on-load tap-changer. As stated in the description of type tests in GB/T 10230.1, type tests may be performed on one on-load tap-changer or on components of an on-load tap-changer. Therefore, for combined on-load tap-changers, conducting type tests separately on the diverter switch and the tap selector shall not affect the test results.
The type test items for diverter switches or selector switches and tap selectors are shown in Table 1.
Table 1 Type test items for diverter switches or selector switches and tap selectors
Test object Test item Subclause
Diverter switch or selector switch Mechanical test 5.1.2
Individual seal test 5.1.3
Insulation test 5.1.4
Contact temperature rise test 5.1.5
Short-circuit current test 5.1.6
Switching test 5.1.7
Transition impedance test 5.1.8
Tap selector Mechanical test 5.1.9
Insulation test 5.1.10
Contact temperature rise test 5.1.11
Short-circuit current test 5.1.12
5.1.2 Mechanical test of diverter switch or selector switch
5.1.2.1 Simulated transformer drying process
Before type tests, the on-load tap-changer (including the diverter switch and tap selector) shall first undergo a transformer drying process to verify that no material deformation or damage occurs to the switch during the drying process of the transformer active part. The maximum drying temperature, maximum temperature rise rate, time sequence and vacuum degree shall follow conventional drying methods, and any variation limits shall be stated by the on-load tap-changer manufacturer.
5.1.2.2 Mechanical endurance test
To ensure smooth test execution, a dedicated test rig shall be fabricated, which shall be equipped with certain protection and monitoring functions. The mechanical endurance test may be operated continuously. It should be noted that the operating frequency of the motor drive is much higher than the normal operating frequency, and additional cooling measures shall be taken for the motor.
More than 10 oscillograms of the on-load tap-changer switching sequence shall be recorded with a DC waveform recorder before and after the test respectively.
A certain number of DC oscillograms shall also be recorded periodically during the test to monitor the operation sequence of the on-load tap-changer. The oscillograms shall reflect the opening and closing times of each contact during operation. Analysis of all these oscillograms or monitoring records shall demonstrate that no significant change has occurred in the switching characteristics of the tap-changer.
During the test, no parts shall be replaced except for defined wear parts, but normal maintenance of the tap-changer is permitted at maintenance intervals stated by the manufacturer. The function of the tap-changer and the wear condition of moving parts shall be inspected at each maintenance.
The number of mechanical endurance test operations and the ambient temperature requirements for diverter switches and selector switches shall comply with the following procedures in accordance with the provisions of GB/T 10230.1:
——No less than 500 000 operations under alternating hot and cold oil conditions; 250 000 operations at an oil temperature of not less than 75°C; and 250 000 operations at an oil temperature below 75°C. 100 operation waveforms shall be recorded at the beginning and end of the test to evaluate the switching time;
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test classification
5 Tests for on-load tap-changers
6 Tests for off-circuit tap-changers
7 Tests for motor‑driven operating mechanism and associated controller
Annex A (Informative) Interpretation of on-load tap-changer switching waveforms
Figure 1 DC composite waveform of diverter switch with double-resistor transition
Figure 2 Coordination sequence test between tap selector preselection and diverter switch
Figure 3 Split waveform test of vacuum-type diverter switch
Figure 4 Test arrangement for operation test at maximum permissible static pressure
Figure 5 Test arrangement for oil column positive pressure method
Figure 6 Test arrangement for oil column negative pressure method
Figure 7 Test arrangement for gas positive pressure method
Figure 8 Test arrangement for individual seal test
Figure 9 Time sequence of test voltage application
Figure 10 Arrangement of current-carrying circuit and temperature measuring points for diverter switch temperature rise test
Figure 11 Short-circuit test current expressed as multiples of maximum rated through-current
Figure 12 Current-carrying circuit for diverter switch short-circuit current test
Figure 13 Transformer compensation method
Figure 14 Resonance method
Figure 15 Determination of test parameters in waveforms acquired from switching test
Figure 16 Test arrangement for gas generation pattern test of vacuum-type on-load tap-changers
Figure 17 Breaking capacity test of change-over contacts for vacuum-type on-load tap-changers
Figure 18 Breaking strength test of polarity selector contacts
Figure 19 Test arrangement for pressure and vacuum test of off-circuit tap-changers
Figure 20 Time sequence of test voltage application
Figure A.1 Example of DC composite waveform for non‑vacuum type on‑load tap‑changer
Figure A.2 Example of switching waveform for vacuum‑type on‑load tap‑changer
Figure A.3 Switching‑circuit configurations and composite waveforms for non‑vacuum‑type on‑load tap‑changers
Figure A.4 Non‑synchronism time of switching waveforms
Figure A.5 Example of DC composite waveform
Figure A.6 Example of DC composite waveform from winding‑mounted testing
Figure A.7 Test example of eliminating "false bounce" waveforms by increasing test current
Table 1 Type test items for diverter switches or selector switches and tap selectors
Table 2 Record table of coordination sequence between tap selector preselection and diverter switch
Table 3 Test voltage levels for on-load tap-changers
Table 4 Contact temperature-rise limits for on-load tap-changers
Table 5 Routine test items for on-load tap-changers
Table 6 Special test items for on-load tap-changers
Table 7 Oil chromatography record table for switching operations of vacuum-type on-load tap-changers
Table 8 Type test items for off-circuit tap-changers
Table 9 Test voltage levels for off-circuit tap-changer
Table 10 Contact temperature-rise limits for off-circuit tap-changer
Table 11 Routine test items for off-circuit tap-changers
Table 12 Type test items for the motor‑driven operating mechanism
Table 13 Routine test items for the motor-driven operating mechanism
JB/T 8314-2025 Test guide for tap-changers
1 Scope
This document specifies the classification of tap-changer tests, as well as the items and procedures for routine tests, type tests and special tests.
This document is applicable to tests for oil-immersed and gas-insulated on-load tap-changers, off-circuit tap-changers and their motor drives and controllers. Tests for on-load tap-changers with reactance transition and other types of tap-changers shall be applied by reference.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions 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 4208 Degrees of protection provided by enclosure (IP code)
GB/T 10230.1 Tap-changers - Part 1: Performance requirements and test methods
3 Terms and definitions
No terms and definitions are defined in this document.
4 Test classification
4.1 Type test
A type test is a test that comprehensively assesses product performance in accordance with the provisions of GB/T 10230.1, including the full set of type tests conducted during new product finalization, and all or part of the tests conducted when major modifications are made to the design, process or key raw materials. Type tests shall be carried out on products that have passed routine tests.
For combined on-load tap-changers, type tests for the diverter switch and the tap selector may be conducted separately, and different test items may be assessed on multiple prototypes.
4.2 Routine test
A routine test is a test conducted on each product before delivery, with the purpose of ensuring the performance reliability of each product. Tests shall generally be conducted on the complete product after final assembly.
4.3 Special test
A test conducted to verify a specific performance of the product as agreed between the user and the manufacturer.
5 Tests for on-load tap-changers
5.1 Type test
5.1.1 General
There are two structural types of on-load tap-changers. One is the combined on-load tap-changer composed of an independent tap selector and an independent diverter switch. The other is the selector switch integrating the functions of both the tap selector and the diverter switch, also known as the integrated on-load tap-changer. As stated in the description of type tests in GB/T 10230.1, type tests may be performed on one on-load tap-changer or on components of an on-load tap-changer. Therefore, for combined on-load tap-changers, conducting type tests separately on the diverter switch and the tap selector shall not affect the test results.
The type test items for diverter switches or selector switches and tap selectors are shown in Table 1.
Table 1 Type test items for diverter switches or selector switches and tap selectors
Test object Test item Subclause
Diverter switch or selector switch Mechanical test 5.1.2
Individual seal test 5.1.3
Insulation test 5.1.4
Contact temperature rise test 5.1.5
Short-circuit current test 5.1.6
Switching test 5.1.7
Transition impedance test 5.1.8
Tap selector Mechanical test 5.1.9
Insulation test 5.1.10
Contact temperature rise test 5.1.11
Short-circuit current test 5.1.12
5.1.2 Mechanical test of diverter switch or selector switch
5.1.2.1 Simulated transformer drying process
Before type tests, the on-load tap-changer (including the diverter switch and tap selector) shall first undergo a transformer drying process to verify that no material deformation or damage occurs to the switch during the drying process of the transformer active part. The maximum drying temperature, maximum temperature rise rate, time sequence and vacuum degree shall follow conventional drying methods, and any variation limits shall be stated by the on-load tap-changer manufacturer.
5.1.2.2 Mechanical endurance test
To ensure smooth test execution, a dedicated test rig shall be fabricated, which shall be equipped with certain protection and monitoring functions. The mechanical endurance test may be operated continuously. It should be noted that the operating frequency of the motor drive is much higher than the normal operating frequency, and additional cooling measures shall be taken for the motor.
More than 10 oscillograms of the on-load tap-changer switching sequence shall be recorded with a DC waveform recorder before and after the test respectively.
A certain number of DC oscillograms shall also be recorded periodically during the test to monitor the operation sequence of the on-load tap-changer. The oscillograms shall reflect the opening and closing times of each contact during operation. Analysis of all these oscillograms or monitoring records shall demonstrate that no significant change has occurred in the switching characteristics of the tap-changer.
During the test, no parts shall be replaced except for defined wear parts, but normal maintenance of the tap-changer is permitted at maintenance intervals stated by the manufacturer. The function of the tap-changer and the wear condition of moving parts shall be inspected at each maintenance.
The number of mechanical endurance test operations and the ambient temperature requirements for diverter switches and selector switches shall comply with the following procedures in accordance with the provisions of GB/T 10230.1:
——No less than 500 000 operations under alternating hot and cold oil conditions; 250 000 operations at an oil temperature of not less than 75°C; and 250 000 operations at an oil temperature below 75°C. 100 operation waveforms shall be recorded at the beginning and end of the test to evaluate the switching time;
Contents of JB/T 8314-2025
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test classification
5 Tests for on-load tap-changers
6 Tests for off-circuit tap-changers
7 Tests for motor‑driven operating mechanism and associated controller
Annex A (Informative) Interpretation of on-load tap-changer switching waveforms
Figure 1 DC composite waveform of diverter switch with double-resistor transition
Figure 2 Coordination sequence test between tap selector preselection and diverter switch
Figure 3 Split waveform test of vacuum-type diverter switch
Figure 4 Test arrangement for operation test at maximum permissible static pressure
Figure 5 Test arrangement for oil column positive pressure method
Figure 6 Test arrangement for oil column negative pressure method
Figure 7 Test arrangement for gas positive pressure method
Figure 8 Test arrangement for individual seal test
Figure 9 Time sequence of test voltage application
Figure 10 Arrangement of current-carrying circuit and temperature measuring points for diverter switch temperature rise test
Figure 11 Short-circuit test current expressed as multiples of maximum rated through-current
Figure 12 Current-carrying circuit for diverter switch short-circuit current test
Figure 13 Transformer compensation method
Figure 14 Resonance method
Figure 15 Determination of test parameters in waveforms acquired from switching test
Figure 16 Test arrangement for gas generation pattern test of vacuum-type on-load tap-changers
Figure 17 Breaking capacity test of change-over contacts for vacuum-type on-load tap-changers
Figure 18 Breaking strength test of polarity selector contacts
Figure 19 Test arrangement for pressure and vacuum test of off-circuit tap-changers
Figure 20 Time sequence of test voltage application
Figure A.1 Example of DC composite waveform for non‑vacuum type on‑load tap‑changer
Figure A.2 Example of switching waveform for vacuum‑type on‑load tap‑changer
Figure A.3 Switching‑circuit configurations and composite waveforms for non‑vacuum‑type on‑load tap‑changers
Figure A.4 Non‑synchronism time of switching waveforms
Figure A.5 Example of DC composite waveform
Figure A.6 Example of DC composite waveform from winding‑mounted testing
Figure A.7 Test example of eliminating "false bounce" waveforms by increasing test current
Table 1 Type test items for diverter switches or selector switches and tap selectors
Table 2 Record table of coordination sequence between tap selector preselection and diverter switch
Table 3 Test voltage levels for on-load tap-changers
Table 4 Contact temperature-rise limits for on-load tap-changers
Table 5 Routine test items for on-load tap-changers
Table 6 Special test items for on-load tap-changers
Table 7 Oil chromatography record table for switching operations of vacuum-type on-load tap-changers
Table 8 Type test items for off-circuit tap-changers
Table 9 Test voltage levels for off-circuit tap-changer
Table 10 Contact temperature-rise limits for off-circuit tap-changer
Table 11 Routine test items for off-circuit tap-changers
Table 12 Type test items for the motor‑driven operating mechanism
Table 13 Routine test items for the motor-driven operating mechanism
