By sion932 
As a crucial national recommended standard in the field of electrical engineering in China, GB/T 22716-2008, titled “Test Specifications of Interturn Insulation of Armature Winding for DC Electrical Machines”, plays a vital role in ensuring the reliability and safety of DC electrical machines. Released on December 30, 2008, and officially implemented on October 1, 2009, this standard was proposed by the China Electrical Equipment Industrial Association, standardized by the National Technical Committee for Rotating Electrical Machines (SAC/TC 26), and jointly drafted by multiple well-known enterprises and research institutions in the electrical industry. This article aims to elaborate on the core content, application scope, and key technical requirements of GB/T 22716-2008, providing a comprehensive reference for relevant engineering and technical personnel.
1. Scope of Application
GB/T 22716-2008 specifies the test methods and limit values for the interturn insulation of armature windings of DC electrical machines. It is mainly applicable to the interturn insulation voltage withstand test of armature windings of DC electrical machines with a rated voltage of 110V and above. For other DC electrical machines, unless there are special requirements, they should also be implemented with reference to this standard. It should be emphasized that this standard does not apply to micro motors, which is a key boundary that needs to be clarified in practical application. In addition, with the development of new energy technologies, this standard also provides important reference for the integration of automotive-grade standards and industrial standards in the field of new energy-driven motors.
2. Core Test Items and Technical Requirements
The standard classifies the interturn insulation test of armature windings into three main stages: pre-installation inspection test of coils, post-installation inspection test of coils, and interturn impulse voltage withstand test of DC electrical machines (armature windings). Each stage has clear test purposes, methods and limit requirements to ensure comprehensive control of insulation quality throughout the manufacturing process.
2.1 Pre-installation Inspection Test of Coils
The purpose of this test is to control the interturn insulation quality of individual coils. During the test, the actual state of the coil in the iron core slot should be simulated: the turns of the test coil should be fixed, and the coil should be placed on a rack with good insulation to the ground. The test requirements vary according to the type and rated voltage of the motor:
- For general-purpose motors with a rated voltage of 660V and below, if the interturn insulation quality is stable and mass production has been formed, the individual coils and equalizing lines generally do not need to undergo the pre-installation interturn voltage withstand inspection test.
- For large motors (with an armature outer diameter of 990mm and above), special-purpose motors such as hoisting and metallurgy, and motors with a rated voltage above 660V, individual coils and equalizing lines must undergo pre-installation interturn voltage withstand inspection tests.
The test methods include two types: voltage withstand test between different coil units and voltage withstand test within the same coil unit. For the voltage withstand test between different coil units, power frequency voltage or DC voltage is preferred. The specific limit values are as follows: For general-purpose motors with a rated voltage of 660V and below, the effective value of the power frequency test voltage is not less than 220V, and the DC test voltage is not less than 400V; for special-purpose motors such as hoisting and metallurgy and motors with a rated voltage above 660V, the effective value of the power frequency test voltage is not less than 530V, and the DC test voltage is not less than 960V. The test time for both power frequency voltage and DC voltage is 1s to 3s. For the interturn voltage withstand test of the same coil unit, impulse voltage is used, the peak value of the impulse voltage for each coil unit is not less than 700V, and the number of impulses is not less than 5 times.
2.2 Post-installation Inspection Test of Coils
This test is used to assess the interturn insulation quality of the armature winding, which should be carried out after the armature winding is installed and箍ed but before impregnation. It can also be carried out at other stages of the armature winding manufacturing process according to needs. The test method is to directly apply the impulse voltage generated by capacitor discharge between the commutator segments, and the armature shaft should be grounded during the test. The judgment of interturn short circuit can adopt the waveform comparison method: comparing the waveform of the test winding with the normal waveform, and those with consistent waveforms are qualified; other effective judgment methods can also be used. According to the winding type, the test methods are divided into span method and segment method:
- Span method: The number of commutator segments within the selected span should be determined according to the winding type and test equipment to make the peak value of the impulse voltage between segments meet the requirements, generally 5 to 7 segments are recommended. The test voltage applied to the sample should be lower than 1.8 times the effective value of the factory power frequency test voltage for insulation to ground. To ensure that each segment is subjected to the voltage test under the same conditions, it is recommended to test each segment one by one (the number of tests can be reduced according to the connection mode of the equalizing line).
- Segment method: Test the adjacent pairs of commutator segments in turn. During the test, if a high induced voltage is generated in the untested coil, grounding devices should be installed on the commutator segments on both sides of the test commutator segment and grounded well.
The test limit values are divided according to the motor use and rated voltage: for general-purpose motors with a rated voltage of 660V and below, the peak value of the intersegment impulse voltage is not less than 350V; for special-purpose motors such as hoisting and metallurgy and motors with a rated voltage above 660V, the peak value of the intersegment impulse voltage is not less than 500V; the number of impulses is not less than 5 times in both cases.
2.3 Interturn Impulse Voltage Withstand Test of DC Electrical Machines (Armature Windings)
The interturn impulse voltage withstand test of DC electrical machines (armature windings) should be carried out on the armature windings before final assembly in accordance with the provisions of 5.3 and 5.4 of the standard, and it is also allowed to carry out after the armature windings are installed and箍ed but before impregnation. This test is the final inspection of the interturn insulation quality of the armature winding, which is of great significance to ensure the overall performance and operational safety of the DC electrical machine.
3. Terminology and Definition
To ensure the unity and accuracy of the understanding and application of the standard, GB/T 22716-2008 defines two key terms:
- Span method: A method for testing the interturn insulation of the armature winding of a DC electrical machine with impulse voltage. Select a span on the armature commutator and apply impulse voltage between the first and last commutator segments for the test.
- Segment method: A method for testing the interturn insulation of the armature winding of a DC electrical machine with impulse voltage. Apply impulse voltage between two adjacent commutator segments of the armature commutator for the test.
4. Significance and Application Value
The formulation and implementation of GB/T 22716-2008 have established a unified technical standard for the interturn insulation test of armature windings of DC electrical machines in China. It not only provides clear guidance for the manufacturing, testing and quality control of DC electrical machines, but also helps to improve the overall reliability and service life of DC electrical machines, and reduce the failure rate caused by interturn insulation problems. In the context of the continuous development of industrial automation and new energy industries, the application of this standard will be more extensive, providing strong technical support for the healthy development of related industries.
GB/T 22716-2008 is a core standard in the field of interturn insulation testing of armature windings of DC electrical machines. It covers the whole process of coil manufacturing and winding assembly through clear application scope, detailed test methods and strict limit requirements. Mastering and implementing this standard is crucial for ensuring the quality and safety of DC electrical machines. In the future, with the continuous progress of technology, it is necessary to pay attention to the integration and development of this standard with emerging technologies and fields, so as to better adapt to the new needs of industrial development.
References
- [1] GB/T 22716-2008, Test Specifications of Interturn Insulation of Armature Winding for DC Electrical Machines[S].
- [2] Analysis and Testing Encyclopedia Network. GB/T 22716-2008 Test Specifications of Interturn Insulation of Armature Winding for DC Electrical Machines[EB/OL].
- [3] Frontier Labs Industry Laboratory. GB/T 22716-2008 Test Specifications of Interturn Insulation of Armature Winding for DC Electrical Machines[EB/OL].
- [4] Jianbiao Network. Details of GB/T 22716-2008[EB/OL].
- [5] Ai Shuo Electric. Standards and Technical Development of Interturn Insulation Testing for New Energy-Driven Motors[EB/OL].