GB/T 20833.1-2021 PDF English
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Rotating electrical machines - The winding insulation - Part 1: Off-line partial discharge measurements
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Rotating electrical machines -- The stator winding insulation of rotating electrical machines -- Part 1: Off-line partial discharge measurements
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The guide for partial discharge measurements and evaluation on stator bar and winding insulation of rotating machinery
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PDF Preview: GB/T 20833.1-2021
GB/T 20833.1-2021: PDF in English (GBT 20833.1-2021) GB/T 20833.1-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.160.01
K 20
GB/T 20833.1-2021 / IEC 60034-27-1:2017
Replacing GB/T 20833.1-2016
Rotating Electrical Machines – The Winding Insulation –
Part 1: Off-Line Partial Discharge Measurements
(IEC 60034-27-1:2017, Rotating Electrical Machines – Part 27-1: Off-
Line Partial Discharge Measurements on the Winding Insulation, IDT)
ISSUED ON: MARCH 09, 2021
IMPLEMENTED ON: OCTOBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 6
1 Scope ... 8
2 Normative References ... 9
3 Terms and Definitions ... 9
4 Nature of PD in Rotating Machines ... 12
5 Measuring Technologies and Instrumentation ... 15
6 Visualization of Measurements ... 18
7 Test Circuits ... 21
8 Normalization of Measurements ... 27
9 Test Procedures ... 30
10 Interpretation of Test Results ... 36
11 Test Report ... 42
Annex A (Informative) Influence Parameters of Test Frequency to Testing Procedure
... 46
Annex B (Informative) Alternative Methods to Determine Discharge Magnitudes ... 48
Annex C (Informative) Other Off-Line Methods for PD Detection and Methods for
Localization ... 51
Annex D (informative) External noise, Disturbance and Sensitivity ... 53
Annex E (informative) Methods of Disturbance Suppression ... 57
Annex F (informative) Interpretation of PD Magnitude Data and Phase Resolved PD
Patterns ... 63
Annex G (informative) Test Circuits for Complete Windings ... 68
Annex H (Informative) Wide-Band and Narrow-Band Measuring Systems ... 74
Bibliography ... 76
Foreword
GB/T 20833 Rotating Electrical Machines – The Winding Insulation can be divided into the
following 4 parts:
--- Part 1: Off-Line Partial Discharge Measurements;
--- Part 2: On-Line Partial Discharge Measurements;
--- Part 3: Dielectric Dissipation Factor Measurement;
--- Part 4: Measurement of Insulation Resistance Polarization Index.
This Part is Part 1 of GB/T 20833.
This Part was drafted as per the rules stipulated in GB/T 1.1-2009.
This Part replaced GB/T 20833.1-2016 Rotating Electrical Machines – The Stator Winding
Insulation of Rotating Electrical Machines – Part 1: Off-Line Partial Discharge Measurements.
Compared with GB/T 20833.1-2016, the major technical changes of this Part are as follows:
--- Modify the Scope of the standard and Normative References (see Clause 1 and Clause 2
of this Edition; Clause 1 and Clause 2 of the 2016 Edition);
--- Add Terms and Definitions (see Clause 3 of this Edition);
--- Modify the nature of partial discharge in the motor (see Clause 4 of this Edition; Clause
4 of the 2016 Edition);
--- Modify the impact of measuring instruments (see 5.4 of this Edition; 5.4 of the 2016
Edition);
--- Modify the minimum range of partial discharge data expression (see 6.2 of this Edition;
6.2 of the 2016 Edition);
--- Add calibration pulse level and tolerance (see 7.1 of this Edition);
---Modify the standard measurement (see 7.3.2 and 7.3.3 of this Edition; 7.3.2 of the 2016
Edition);
--- Add the use of integrated test equipment (see 7.3.4 of this Edition);
--- Modify the partial discharge measurement of windings and winding components (see 9.1
of this Edition; 9.1 of the 2016 Edition);
--- Delete the electromagnetic probe (see 9.2.2 of the 2016 Edition);
--- Modified the evaluation of test results (see 10.1, 10.2.1 and 10.3.1 of this Edition; 10.1,
10.2.1 and 10.3.1 of the 2016 Edition);
--- Delete the annex of on-line partial discharge measurement (see Annex A of the 2016
Edition);
--- Add the influence of the test frequency parameter on the test process (see Annex A of this
Edition);
--- Add other methods for determining the amplitude of partial discharge (see Annex B of
this Edition);
--- Modify the method of off-line partial discharge detection and off-line location (see Annex
C of this Edition, Annex B of the 2016 Edition);
--- Add interpretation of partial discharge measurement and induction discharge/vibration
spark from terminal and star-connected neutral point (see Annex D of this Edition);
--- Add the complete winding measurement connection circuit (see Annex G of this Edition);
--- Modify the broadband and narrowband systems (see Annex H, 5.4 of the 2016 Edition).
This Part used translation method to equivalently adopt IEC 60034-27-1:2017 Rotating
Electrical Machines – Part 27-1: Off-Line Partial Discharge Measurements on the Winding
Insulation.
The Chinese documents that have consistent correspondence with the international documents
cited in this part are as follows:
--- GB/T 7354-2018 High-voltage test techniques - Partial discharge measurements (IEC
60270-2000, MOD);
--- GB/T 16927.1-2011 High-voltage test techniques—Part 1: General definitions and test
requirements (IEC 60060-1:2010, MOD);
--- GB/T 16927.2-2013 High-voltage test techniques - Part 2: Measuring systems (IEC
60060-2:2010, MOD);
--- GB/T 17948.4-2016 Rotating electrical machines - Functional evaluation of insulation
systems - Test procedures for form-wound windings - Evaluation by electrical endurance
(IEC 60034-18-32:2010, IDT);
--- GB/T 22720.2-2019 Rotating electrical machines - Qualification tests for the partial
discharge resistant electrical insulation systems (Type Ⅱ) used in rotating electrical
machines fed from voltage converters (IEC 60034-18-42:2017, IDT);
--- GB/T 20833.2-2016 Rotating electrical machines - The stator winding insulation of
Rotating Electrical Machines – The Winding Insulation –
Part 1: Off-Line Partial Discharge Measurements
1 Scope
This Part of GB/T 20833 provides a common basis with respect to partial discharge off-line
measurements on the winding insulation of rotating electrical machines:
– measuring techniques and instruments;
– the arrangement of test circuits;
– normalization and testing procedures;
– noise reduction;
– the documentation of test results;
– the interpretation of test results.
The measurement methods described in this document are applicable to stator windings of
machines with or without conductive slot coating and to the stator windings of machines made
with form wound or random wound windings. In special cases like high voltage rotor field
windings, this document is applicable as well. The measurement methods are applicable when
testing with alternating sinusoidal voltages from 0.1 Hz up to 400 Hz; see Annex A.
Interpretation guidelines are given in this document and are applicable only if all the following
requirements are fulfilled:
– Measurements performed with power frequency of 50 Hz or 60 Hz, or when testing with
power supply within a frequency range of 45 Hz to 65 Hz.
– Form wound windings and winding components such as bars and coils.
– Winding with conductive slot coating. This is usually valid for machines with voltage
rating of 6 kV and higher.
For machines with random wound windings, form-wound windings without conductive slot
coating, and testing at frequencies differing from power frequencies, the interpretation
guidelines are not applicable. The testing procedures for off-line PD-measurements of this
document can be used for assessing the uniform quality of manufacturing or/and the trending
of these kind of windings as well as converter driven machine windings.
NOTE: Testing of low voltage machines with so called Type I insulation systems is defined in IEC 60034-
18-41. Testing procedures for qualification of converter driven high voltage machines with so called Type
II insulation systems are dealt with in IEC 60034-18-42 (in addition to the optional electric tests described
therein).
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) is applicable to this
Document.
IEC 60034-18-32 Rotating Electrical Machines – Part 18-32: Functional Evaluation of
Insulation Systems – Test Procedures for Form-Wound Windings – Evaluation by
Electrical Endurance
IEC 60034-18-42 Rotating Electrical Machines – Part 18-42: Partial Discharge Resistant
Electrical Insulation Systems (Type II) Used in Rotating Electrical Machines Fed from
Voltage Converters – Qualification Tests
IEC TS 60034-27-2 Rotating Electrical Machines – Part 27-2: On-Line Partial Discharge
Measurements on the Stator Winding Insulation of Rotating Electrical Machines
IEC 60034-27-4 Rotating Electrical Machines – Part 27-4: Measurement of Insulation
Resistance and Polarization Index of Winding Insulation of Rotating Electrical Machines
IEC 60060-1 High-Voltage Test Techniques – Part 1: General Definitions and Test
Requirements
IEC 60060-2 High-Voltage Test Techniques – Part 2: Measuring Systems
IEC 60270:2000 High-Voltage Test Techniques – Partial Discharge Measurements
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in IEC 60270 and the
following apply.
3.1 Partial discharge; PD
Localized electrical discharge that only partially bridges the insulation between conductors and
which can or cannot occur adjacent to a conductor.
3.2 Off-line measurement
at phase terminal side of stator winding. The PD activity results in increased ageing through
erosion of the main insulation. Coil loosening can also lead to mechanical abrasion in a severe
case.
As insulation erosion is caused by high voltage induced slot discharges, it will occur more
severely at bars/coils near HV terminals. Therefore, off-line PD measurements will provide
different PD intensity and, sometimes, patterns at terminal and neutral side, in the presence of
slot discharges.
Bar or coil vibration within the slots during operation, caused e.g., by forces due to the
electromagnetic field and in the condition that the bars and coils are not tight anymore, may be
the initial state of slot portion coating damage. Under certain conditions vibration sparking may
occur during machine operation. This is caused by intermitted interruption of driven currents
which are caused by electromagnetically induced voltages. Although it is not a PD phenomenon
it may occur similarly during measurements.
When the conductive slot coating is deteriorated by the vibration sparking, in standstill these
can be measured as slot discharges. Since vibration sparking is driven by the magnetic field this
phenomenon can occur mainly in the slot section of each bar or coil, from terminal side to
neutral side, the effect may be measured on both sides of the winding. Comparative
measurements including pattern analysis on terminal and neutral side may give an indication
for vibration sparking. F.1.4 provides more background information.
4.2.4 End-winding gap and surface discharges
Partial discharges in the end-winding area may occur at several locations with high local electric
field strengths. Such discharges usually occur at interfaces between different elements of the
stator winding overhang. If the stress control coating of the end-winding becomes ineffective
because of poorly designed interfaces, contamination, porosity, thermal effects, etc., reliable
field grading is no longer ensured and surface discharges will develop, which may gradually
erode the insulation and surface materials. This is normally a slow ageing mechanism. The PD
behavior might be subjected to relatively fast changes due to surface effects.
In addition, PD may occur between phases, for example due to inadequate interface clearance,
at elements of the overhang support system, or as phase to ground discharges on the end-
winding surface.
4.2.5 Foreign conductive materials discharges
Conductive contamination of the winding may result in a strong local concentration of partial
discharges. These may result in a localized damage in the insulation. More dangerous may be
larger metal pieces such as broken bolts or screws, as well as unintentionally forgotten tools.
Beside the local concentration of PD and its potentially damaging effect it may lead to
secondary impact such as immediate mechanical damage or abrasion driven by the impact of
the magnetic field to such metal pieces.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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