JB/T 12685-2016 PDF English
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Stator coils of high-voltage rotating electrical machines - Specification
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JB/T 12685-2016: PDF in English (JBT 12685-2016) JB/T 12685-2016
JB
MECHANICAL INDUSTRY STANDARD
ICS 29.160.01
K 20
Filing No.. 53687-2016
Stator coils of high-voltage rotating electrical machines -
Specification
ISSUED ON. JANUARY 15, 2016
IMPLEMENTED ON. JUNE 01, 2016
Issued by. Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative references... 4
3 Test samples... 5
4 Technical requirements... 5
5 Test method... 9
6 Inspection rules... 11
Stator coils of high-voltage rotating electrical machines -
Specification
1 Scope
This standard specifies the test samples, technical requirements, test methods, and
inspection rules for stator coils (frame coils) of high-voltage AC motors, which have a
heat resistance grade 155 (F) and rated voltage UN of 3 kV, 6 kV, 10 kV, including stator
coils manufactured by molding and VPI (Vacuum Pressure Impregnating) processes.
This standard applies to the quality appraisal of the insulation structure of finished coils
of high-voltage AC motors, which have a rated voltage of 3 kV, 6 kV, 10 kV.
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 standard.
GB 755-2008 Rotating electrical machines - Rating and performance
GB/T 17948.3-2006 Functional evaluation of insulation systems for rotating
electrical machines - Test procedures for form-wound windings - Thermal
evaluation and classification of insulation systems used in machines up to and
including 50 MVA and 15 kV
GB/T 22715-2016 Impulse voltage withstand levels of form-wound stator coils for
rotating a.c. machines
GB/T 22718-2008 Thermal evaluation methods of insulation systems for high-
voltage electrical machines
JB/T 6204 Specifications for withstand voltage test on stator coil and winding
insulation of high voltage AC machines
JB/T 7608-2006 Test method and limited value of loss factor of coil for HV and AC
electric machine
calculated according to the nominal size of the drawing (excluding the anti-corona
layer).
The breakdown voltage value is the lowest value on both sides of a single coil; the
breakdown field strength is the average value.
5.6 Corona starting voltage
The specimen is subjected to a corona starting voltage test in a dark room. The test
voltage waveform shall be an actual sine wave, which is subject to visual inspection.
5.7 Dielectric loss tangent
5.7.1 Normal dielectric loss tangent tanδ and its increment Δtanδ
The measurement shall be carried out at room temperature. The length of the measuring
electrode (see 5.1) shall be the length of the coil slot; the measuring electrode shall be
connected to the guard electrode. The width of the guard electrode shall be no less than
10 mm. The gap between the guard electrode and the measuring electrode shall be no
more than 4 mm, generally within 2 mm ~ 4 mm. The measuring voltage starts from
0.2UN and is measured every 0.2UN until 1.0UN. The main test equipment shall meet
the requirements of JB/T 7608-2006.
5.7.2 Hot dielectric loss tangent tanδ
The specimen shall be placed in an oven with hot air circulation, and the test
temperature shall be controlled at 155 °C ± 2 °C. After keeping it for 1 h, measure it
under the test voltage of 0.6UN. The length of the measuring electrode is the length of
the coil slot; the measuring electrode shall be connected to the guard electrode. The
main test equipment shall meet the requirements of JB/T 7608-2006.
5.8 Voltage durability test
5.8.1 Quality assurance test
Before the voltage durability test, the quality assurance test shall be carried out
according to the following requirements.
- Specimen appearance inspection;
- Voltage withstanding test according to GB 755-2008;
- Impact voltage level test according to GB/T 22715-2016.
5.8.2 Voltage durability test
Under room temperature conditions, apply a power frequency AC voltage of 2.17 UN
or 2.53 UN to the insulation of the coil slot until the coil insulation breaks down. The
test voltage waveform shall be an actual sine wave. The accumulated time of electrical
aging is the failure time of the specimen.
The specimen shall be at least 2 frame coils or 4 bar coils. Any slot of the frame coil
and its end or the entire bar coil is regarded as one specimen. Anti-corona measures
shall be taken for all specimens.
5.8.3 Judgment criteria
The judgment criteria for voltage durability test are as follows.
a) If the failure time of all specimens is not less than 400 h (test voltage is 2.17UN)
or 250 h (test voltage is 2.53UN), it can be judged that the product it represents
meets the test requirements.
b) If the failure time of the specimen is within 200 h ~ 400 h (test voltage is 2.17UN)
or 125 h ~ 250 h (test voltage is 2.53UN), but the number of failed specimens is
not more than 26% of the total, then an additional frame coil or 2 bar coils shall
be selected for testing. If the number of specimens put into the electrical aging
test is not less than 6, no additional specimens are required. All remaining coils
(including additionally selected coils) shall pass the test. If there are still
specimens with a failure time of less than 400 h (test voltage is 2.17UN) or 250 h
(test voltage is 2.53UN) during the repeated test, it shall be judged that the product
it represents does not meet the test requirements.
c) If the failure time of the specimen is within 200 h ~ 400 h (test voltage is 2.17UN)
or 125 h ~ 250 h (test voltage is 2.53UN), meanwhile the number of failed
specimens is greater than 26% of the total, it shall be determined that the product
it represents does not meet the test requirements.
d) If the failure time of the specimen is less than 200 h (test voltage is 2.17UN) or
125 h (test voltage is 2.53UN), it shall be determined that the product it represents
does not meet the test requirements; the breakdown coil shall be dissembled and
analyzed; improvement measures shall be formulated and retested.
6 Inspection rules
6.1 Sampling inspection
Sampling inspection shall be carried out every six months; the number of inspections
can be increased if necessary. The sampling inspection items are as follows.
a) Test of insulation withstand power frequency voltage to ground;
b) Withstand impulse voltage level;
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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