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GB/T 21707-2018 English PDF (GBT21707-2018)

GB/T 21707-2018 English PDF (GBT21707-2018)

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GB/T 21707-2018: Insulation specification for variable frequency adjustable speed definite purpose converter-fed three-phase induction motors

This standard gives the insulation specifications for variable frequency adjustable speed definite purpose converter-fed three-phase induction motors, including terms and definitions, technical requirements and inspection rules. This standard is applicable to variable frequency adjustable speed definite purpose converter-fed three-phase induction motors with rated voltage of 1140 V and below.
GB/T 21707-2018
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 29.160.01
K 20
GB/T 21707-2008
Insulation specification for variable frequency
adjustable speed definite purpose converter-fed
three-phase induction motors
ISSUED ON. JUNE 07, 2018
IMPLEMENTED ON. JANUARY 01, 2019
Issued by. State Market Regulatory Administration;
Standardization Administration of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Technical requirements ... 7
5 Inspection rules ... 11
Appendix A (Normative) High frequency impact tester waveform parameter
measurement guideline ... 12
Appendix B (Normative) Testing the volatiles of the impregnated resin ... 15 Appendix C (Informative) Evaluation procedure for insulation system of variable frequency motor ... 17
References ... 20
Foreword
This standard was drafted in accordance with the rules given in GB /T 1.1-2009. This standard replaces GB T 21707-2008 ?€?Insulation specification for variable frequency adjustable speed definite purpose converter-fed three-phase
induction motors?€?. As compared with GB/T 21707-2008, the main technical changes are as follows.
- MODIFY the scope (see clause 1; clause 1 of the 2008 version);
- ADD the terms and definitions (see clause 3);
- ADD the requirements for enameled flat wire and glass-fiber wound
enameled flat wire (see 4.1.1);
- MODIFY the requirements for the enameled round wire (see Table 2; Table 1 of the 2008 version);
- MODIFY the requirements for the volatiles of impregnated resin (see 4.1.2; 3.1.2 of the 2008 version);
- MODIFY the waveform parameters of the high frequency impact resistance of electromagnetic line (see Table 3; 3.1.1 of the 2008 version);
- ADD the assessment of Type I insulation systems (see 4.3.4);
- ADD the assessment of Type II insulation systems (see 4.3.5);
- DELETE the high-frequency pulse resistance evaluation of the insulation system (see 4.3 of 2008 version);
- DELETE the informative appendix ?€?IEC 62068-1 Pulse voltage
characteristics?€? (see Appendix A of the 2008 version);
- ADD the normative appendix ?€?Guidelines for the measurement of waveform parameters of high frequency impact testers?€? (see Appendix A);
- ADD the informative appendix ?€?Assessment specification for inverter
structures of variable frequency motors?€? (see Appendix C).
This standard was proposed by the China Electrical Equipment Industry
Association.
This standard shall be under the jurisdiction of the National Rotating Electric Machine Standardization Technical Committee (SAC/TC 26).
Drafting organizations of this standard. Shanghai Motor System Energy
Insulation specification for variable frequency
adjustable speed definite purpose converter-fed
three-phase induction motors
1 Scope
This standard gives the insulation specifications for variable frequency adjustable speed definite purpose converter-fed three-phase induction motors, including terms and definitions, technical requirements and inspection rules. This standard is applicable to variable frequency adjustable speed definite purpose converter-fed three-phase induction motors with rated voltage of 1140 V and below.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.
GB/T 4074.7-2009 Winding wires - Test methods - Part 7. Test procedure for the determination of the temperature index of enameled winding wires
GB/T 5591.3 Combined flexible materials for electrical insulation - Part 3. Specifications for individual materials
GB/T 6109.20 Enameled round winding wire - Part 20. Polyester on
polyesterimide overcoated with polyamide-imide enameled round copper
wire class 200
GB/T 7095.6 Enameled rectangular copper winding wires - Part 6. Polyester or polyesterimide overcoated with polyamide-imide enameled rectangular
copper wire class 200
GB/T 7672.5 Glass-fiber wound winding wires - Part 5. Glass-fiber wound resin or varnish impregnated bare or enameled rectangular copper wire
temperature index 200
GB/T 11026.4-2012 Electrical insulating materials - Thermal endurance
4.1.7 Lead wire
The continuous running conductor of the lead wire has a maximum temperature of at least 125 ??C. The connection between the lead wire and the winding wire can be protected by the corresponding thermosetting adhesive tape, its
conventional performance shall meet the technical requirements of the relevant products.
4.1.8 Casing
The heat resistance of the casing is not less than 155 (F), its conventional performance shall meet the technical requirements of the relevant products. 4.2 Technical requirements for insulation system
4.2.1 Heat resistance rating
The heat resistance rating shall be no less than 155 (F).
4.2.2 Technical requirements for type I insulation system
Type I insulation system shall meet the technical requirements of GB/T
22720.1-2017.
4.2.3 Technical requirements for type II insulation systems
Type II insulation system shall meet the technical requirements of IEC 60034- 18-42.
4.3 Test methods and test equipment
4.3.1 Evaluation of high frequency impact resistance of electromagnetic wire
4.3.1.1 Specimen preparation
For the evaluation of the high-frequency impact resistance of the
electromagnetic wire, the enameled round wire, the enameled flat wire, or glass-fiber wrapped enameled flat wire which has a nominal conductor diameter of 1.000 mm and a grade 2 paint film thickness is used as the specimen, which is prepared as follows.
- Enameled round wire. It is prepared into the form of ?€?twisted pair?€? in accordance with the provisions of 5.1.1 of GB/T 4074.7-2009;
- Enameled flat wire or glass-fiber wrapped enameled flat wire. It is prepared into the form of ?€?back to back?€? in accordance with the provisions of 5.1.2 of GB/T 4074.7-2009.
oscilloscope to read, measure, and calibrate the power output waveform
parameters. The schematic diagram of the bipolar symmetric square wave is shown in Figure A.2. The steps are as follows.
a) Make the wiring in accordance with Figure A.3, set the measurement
channel of the digital oscilloscope to DC coupling.
b) Adjust the time base and trigger of the digital oscilloscope, to make the voltage signal display stable.
c) Adjust the DC offset and signal amplitude so that the portion between the bottom value and top value of the input surge voltage signal is centered to cover approximately 80% of the screen.
d) Adjust the acquisition rate (time base) of the test channel until the impact front rise time tr can be clearly and accurately displayed on the screen as shown in Figure A.2.
e) Adjust the position of the time cursors a and b to 0.1Up and 0.9Up, read the time t10 and t90 corresponding to the cursor, calculate the impact rise time tr in accordance with the formula (A.1). The calculation method of the impact fall time is the same.
tr = 1.25 (t90 - t10) ...(A.1)
f) Adjust the position of the two voltage amplitude cursors a' and b', as shown in Figure A.2, to read the voltage overshot (Ub).
g) Other parameters such as frequency can be read directly from the
oscilloscope.
Appendix C
(Informative)
Evaluation procedure for insulation system of variable frequency motor
C.1 Overview
This Appendix only briefly describes the evaluation procedures for the type I insulation system and type II insulation system of the variable frequency motor. For detailed evaluation procedures, refer to GB/T 22720.1-2017 and IEC
60034-18-42.
C.2 Evaluation of Type I insulation system
C.2.1 Identification of Type I insulation system
C.2.1.1 Identification procedures
It is advisable to use the model coil or the complete winding as a test piece to carry out an identification test on the type I insulation system, which is carried out in sequence as follows.
a) Pre-diagnostic test;
b) Electrical diagnostic test;
c) High temperature exposure test, high temperature exposure, mechanical vibration, moisture exposure and electrical diagnostic test is performed in order in accordance with GB/T 17948.1 or GB/T 17948.3-2017;
Note. If the heat resistance grade of the insulation system has been
determined in accordance with GB/T 17948.1 and GB/T 17948.3-2017, the
high temperature exposure test is only required under any temperatures
of the three aging temperatures as specified in GB/T 17948.1 and GB/T
17948.3-2017.
d) Partial electrical discharge test, which is performed inter-turns, inter- phases, and ground, respectively, in accordance with GB/T 20833.1-2016
or GB/T 23642-2017. If the partial discharge starting voltage is higher than the specified value, repeat c), otherwise the test is over.
The partial discharge test voltage level is determined by both parties through negotiation. If no data is available, the test voltage for partial discharge can be calculated in accordance with GB/T 22720.1-2017. For motors powered by two- level inverters, the partial discharge test voltage recommendations are shown Table C.2 -- Relationship between stress type and IVIC
Type of stress IVIC
A - Moderate A
B - Medium B
C - Severe C
D - Extreme D
C.3 Evaluation of Type II insulation system
C.3.1 Interturn insulation
Partial discharge test is performed for the inter-turn insulation of type II insulation systems in accordance with GB/T 20833.1-2016 or GB/T 23642-2017. - If there is no partial discharge, no identification test for the inter-turn insulation is required;
- If there is partial discharge, the voltage durability test is performed on the inter-turn insulation at room temperature.
C.3.2 Main insulation
For the identification of the main insulation of type II insulation system, the voltage durability test is carried out in accordance with GB/T 17948.4-2016. C.3.3 Stress gradient structure
The stress gradient structure is tested in turn as follows.
a) Use an impulse power supply to perform a 100 h voltage durability test on the test product;
b) Use a sine wave power supply to perform a 1000 h voltage endurance test on the sample at the fundamental frequency;
c) Repeat a).

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