GB/T 22720.1-2017 English PDF (GBT22720.1-2017)

Delivery: 3 seconds. Download true-PDF + Invoice.
Get QUOTATION in 1-minute: Click GB/T 22720.1-2017
Historical versions: GB/T 22720.1-2017
Preview True-PDF (Reload/Scroll if blank)

GB/T 22720.1-2017: Rotating electrical machines -- Qualification and quality control tests of partial discharge free electrical insulation systems (Type Ⅰ) used in rotating electrical machines fed from voltage converters
GB/T 22720.1-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.160.01
K 20
GB/T 22720.1-2017 / IEC 60034-18-41:2014
Replacing GB/T 22720.1-2008
Rotating Electrical Machines - Qualification and
Quality Control Tests of Partial Discharge Free
Electrical Insulation Systems (Type I) Used in Rotating
Electrical Machines Fed from Voltage Converters
[IEC 60034-18-41:2014, Rotating Electrical Machines - Part 18-41:
Partial Discharge Free Electrical Insulation Systems (Type I) Used in
Rotating Electrical Machines Fed from Voltage Converters -
Qualification and Quality Control Tests, IDT]
ISSUED ON: NOVEMBER 1, 2017
IMPLEMENTED ON: MAY 1, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
Introduction ... 6 
1 Scope ... 8 
2 Normative References ... 8 
3 Terms and Definitions ... 9 
4 Motor Terminal Voltage Generated during Converter Operation ... 14 
5 Electrical Stresses in the Insulation System of Motor Windings ... 18 
6 Types of Motor Insulation ... 22 
7 Stress Categories for Type I Insulation Systems Used in Motors Fed from
Converters ... 22 
8 Qualification and Type Tests of Type I Insulation Systems ... 24 
9 Test Equipment ... 25 
10 Qualification of Type I Insulation Systems ... 27 
11 Type Test Procedures of Type I Insulation Systems ... 32 
12 Exit-factory Inspection ... 34 
13 Analysis, Report and Classification ... 34 
Appendix A (informative) Terminal Voltages of a Converter-fed Motor during
Operation ... 35 
Appendix B (normative) Test Voltages of Type I Insulation Systems ... 38 
Appendix C (normative) Derivation of Allowable Voltages in Operation ... 47 
Appendix NA (informative) Derivation and Example of Conventional Withstand
Voltage Test of Motors with a Rated Voltage of 500 V ... 49 
Bibliography ... 50 
Rotating Electrical Machines - Qualification and
Quality Control Tests of Partial Discharge Free
Electrical Insulation Systems (Type I) Used in Rotating
Electrical Machines Fed from Voltage Converters
1 Scope
This Part specifies the assessment criteria for stator / rotor winding insulation systems
fed from voltage-source pulse-width-modulation (PWM). This Part is applicable to the
stator / rotor winding insulation systems of single-phase or multi-phase AC motors
powdered by converters.
This Part specifies the qualification and quality control (type and exit-factory) tests for
typical samples or complete motors, so as to verify the degree of fitness with voltage-
source converters.
This Part is inapplicable to:
---Rotating electrical machines only started by converters;
---Rotating electrical machines whose rated voltage has an effective value of ≤
300 V;
---Rotor windings of rotating electrical machines with an operating voltage (peak
value) ≤ 200 V.
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 17948.7-2016 Rotating Electrical Machines - Functional Evaluation of Insulation
Systems - General Guidelines (IEC 60034-18-1:2010, IDT)
IEC 60034-18-21 Rotating Electrical Machines - Part 18-21: Functional Evaluation of
Insulation Systems - Test Procedures for Wire-wound Windings - Thermal Evaluation
and Classification
IEC 60034-18-31 Rotating Electrical Machines - Part 18-31: Functional Evaluation of
voltage, PDIV is defined as peak to peak voltage.
3.3 Partial Discharge Extinction Voltage
PDEV
Partial discharge extinction voltage refers to the voltage when the voltage applied to
the sample gradually decreases from a certain relatively high value where partial
discharge is detected to the voltage where no partial discharge can be detected in the
test circuit.
NOTE: for sinusoidal voltage, PDEV is defined as the effective value of voltage; for impulse
voltage, PDEV is defined as peak to peak voltage.
3.4 Peak (impulse) Voltage
Up
Peak (impulse) voltage refers to the highest voltage value that a unipolar impulse can
reach (for example, Up in Figure 1).
NOTE 1: for bipolar impulse voltage, the peak (impulse) voltage is half of the peak to peak
voltage (see Figure 2);
NOTE 2: the definition of peak to peak voltage is described in Chapter 4.
3.5 Steady State Voltage Impulse Magnitude
Ua
Steady state voltage impulse magnitude refers to the final magnitude of the impulse
voltage (see Figure 1).
3.6 Voltage Overshoot
Ub
Voltage overshoot refers to the magnitude of the peak voltage value exceeding the
steady state voltage impulse magnitude (see Figure 1).
3.7 Peak to Peak Impulse Voltage
Upk/pk
Peak to peak impulse voltage refers to the peak to peak voltage at the impulse
repetition rate (see Figure 2).
3.8 Peak to Peak Voltage
3.15 Formette
Formette refers to a special test model used for the evaluation of the electrical
insulation systems for form-wound windings.
3.16 Motorette
Motorette refers to a special test model used for the evaluation of the electrical
insulation systems for wire-wound windings.
3.17 (electric) Stress
(electric) stress refers to electric field strength, which is expressed in V/mm.
3.18 Rated Voltage
UN
Rated voltage refers to the voltage value of the motor under the conditions of power
frequency operation. It is specified by the manufacturer and marked on the nameplate.
3.19 Impulse Voltage Insulation Class
IVIC
Impulse voltage insulation class refers to the safe peak to peak voltage specified by
the manufacturer and related to the rated voltage for the motor fed from a specific
converter. It is marked in the instruction manual and on the nameplate.
3.20 Fundamental Frequency
Fundamental frequency refers to the frequency in the spectrum obtained through the
Fourier transform of the periodic time function. All frequencies in the spectrum are
related to it.
NOTE: for this Part, the fundamental frequency of the motor terminal voltage determines
the speed of the variable frequency motor.
3.21 Impulse Duration / Width
Impulse duration / width refers to the time interval between the first instant and the last
instant when the transient impulse value reaches the specified value of the impulse
magnitude or the specified threshold.
3.22 Jump Voltage
Uj
Jump voltage refers to the change of the voltage at the motor terminal at the beginning
Key:
●---tr = 50 ns;
○---tr = 100 ns;
▼---tr = 200 ns;
▽---tr = 1,000 ns;
l---cable length;
Up /Ua---the ratio of peak voltages at the motor and at the converter terminals
Figure 4 -- Voltage Increment at Motor Terminal due to Reflection as a Function
of Cable Length for Different Impulse Rise Times
5 Electrical Stresses in the Insulation System of Motor
Windings
5.1 Overview
If the winding is subjected to short rise time impulse voltages with an extremely large
magnitude, then, high voltage stresses will be generated in the following locations
(Figure 5 and Figure 6):
---Between conductors in different phases;
---Between the conductor and the ground;
---Between adjacent turns in the line-end coil.