Machinery Industry Standard of the People's Republic of China
JB/T7844-1995
General Technical Conditions for Gas-Pressure Porcelain Bushings
Published on November 24, 1995
Ministry of Machinery Industry of the People's Republic of China
Standard Download Network (www.bzxzw.com)
Implemented on June 1, 1996
Machinery Industry Standard of the People's Republic of China
General Technical Conditions for Gas-Pressure Porcelain Bushings
JB/T7844-1995
This standard adopts the 1st edition of IEC Publication 1264 <Pressure Hollow Insulators for High-Voltage Switchgear and Controlgear> (1994) in a non-equivalent manner. Subject Content and Scope of Application
This standard specifies the technical requirements, test methods, inspection rules, packaging and marking of gas-pressure porcelain bushings. This standard applies to porcelain bushings (hereinafter referred to as porcelain bushings) used in power equipment such as circuit breakers with a rated voltage higher than 1000V and an ambient air temperature of -40 to +40°C, whose internal cavity pressure is greater than normal atmospheric pressure. The gas in the inner cavity of the porcelain bushing can be dry air, inert gas, such as sulfur hexafluoride (SF.), nitrogen (N.), or a mixture thereof. The porcelain bushing is an insulating element of power equipment. The external insulation electrical performance of power equipment is not a characteristic of the porcelain bushing itself, so it is not specified in this standard.
This standard does not apply to porcelain bushings used under conditions sufficient to reduce the performance of the porcelain bushing. 2 Reference standards
GB772—87
Technical conditions for high-voltage insulator porcelain parts
GB775.1~775·3—87
Test methods for insulators
GB2900.883
GB8411.187
JB3384—83
JB/T5896—91
JB/Z94-89
JB/Z262—86||tt ||3 Terms
Electrical terminologyInsulators
Electrical porcelain materialsPart 1Definition, classification and performanceSampling plan for high-voltage insulators
Common insulator terms
Insulator product packaging
Ultrasonic detection of internal defects of porcelain parts
Ceramic sleeve: An insulator that is passed through from one end to the other. It is made of porcelain sleeves, porcelain parts and metal flanges glued together by cement adhesive. It can be composed of a single porcelain sleeve component or multiple porcelain sleeve components. Note: The porcelain parts of the card-mounted structure that do not need to be assembled are also called porcelain sleeves. 3.2 Porcelain sleeve porcelain parts; refers to a single porcelain insulation component that makes up the porcelain sleeve, and it does not have metal accessories. 3.3 Porcelain sleeve components: Porcelain sleeve components are permanently assembled from a porcelain sleeve porcelain part and a fastening device. Such as a combined component used to combine pillars and porcelain sleeve columns.
3.4 Design pressure: The maximum pressure difference between the inside and outside of the porcelain sleeve when it is running under the design temperature conditions. 3.5 Design temperature: The highest temperature that the gas medium in the inner cavity of the porcelain sleeve may reach under normal operating conditions. This is usually the upper limit of the temperature rise of the inner cavity medium caused by the temperature rise caused by the normal rated current and dielectric loss. 3.6 Other terms used in this standard comply with the provisions of GB2900.8 and JB/T5896. 4 Technical requirements
The porcelain sleeve shall be manufactured according to the drawings approved by the prescribed procedures. 4.1
The porcelain sleeve and porcelain parts shall be made of electric porcelain materials that comply with the provisions of GB8411.1. Approved by the Ministry of Machinery Industry on November 24, 1995
Standard Download Network (www.bzxzw.com)
Implementation on June 1, 1996
JB/T78441995
The main dimensional deviation, shape and position deviation and surface roughness of the porcelain sleeve, if not specified in the drawings, shall comply with the following provisions. 4.2
Dimensional deviation of porcelain sleeve
General dimensional deviation of porcelain sleeve shall comply with the provisions of GB772. For the height dimension of porcelain sleeve components for circuit breakers of 2500mm and belowa
, the height deviation is divided into three levels, which can be selected according to the requirements of porcelain sleeve during product design.
I: ±lmm
bzxZ.netI: ±2mm
I: ±4mm
Note: The deviation of porcelain sleeve components with a height of more than 2500mm shall be agreed upon by both the supplier and the buyer. b
Nominal creepage distance: The lower deviation shall not exceed 0.025L+6mm, and the upper deviation shall not be specified (L is the specified creepage distance). Shape and position deviation of porcelain sleeve
The shape and position deviation of porcelain sleeve are specified in Table 1, which can be selected according to the requirements of porcelain sleeve during product design. Table 1 Shape and position deviation of porcelain sleeve
Parallelism of both end faces of porcelain sleeve and porcelain component
Parallelism of upper and lower flange end faces of porcelain sleeve
Not more than
Not more than
Parallelism of shrinkage surface of porcelain sleeve and porcelain component with the end face of flange at the same end not more than
Center eccentricity of mounting holes of upper flange and lower flange of porcelain sleeveCoaxiality of upper (or lower) flange and porcelain sleeve and porcelain component of porcelain sleeveCoaxiality of stop of upper flange and lower flange of porcelain sleeveStraightness of axis of porcelain sleeve
Not more than
Not more than
Not more than
Note: ①H in the table is the height of the sleeve in mm, and D is the maximum inner diameter of the porcelain sleeve in mmI
For porcelain sleeve slenderness ratio H/D>6
, it shall be agreed upon by both parties
②For the shape and position deviation of outlet porcelain sleeve for tank circuit breaker or fully enclosed combination electrical appliance, it shall be agreed upon by both parties. 4.2.3
The surface roughness (R.) of the sealing surface of the porcelain sleeve and the porcelain parts shall not be greater than: 1;3.2μm
1:1.6μm.
4.3 For straight-tube porcelain sleeves with a height of less than 1500mm and a thickness of more than 30mm, ultrasonic detection and inspection shall be carried out. There shall be no defects that can be found by ultrasonic waves inside the porcelain parts, such as raw burning, oxidation, cracking, pores and interlayers. 4.4
The porcelain sleeve shall be glued with cement adhesive made of not less than 525 silicate cement. A layer of buffer shall be applied to the contact surface of the porcelain parts and flanges with the cement adhesive. A layer of waterproof coating shall be applied to the surface of the exposed cement adhesive. 45
The cross-section of the parts shall be homogeneous and dense, and there shall be no penetration after the porosity test. The porcelain sleeve shall be able to withstand three rapid temperature changes without damage. Its hot and cold temperature difference shall comply with the provisions of GB772. The porcelain bushing shall be able to withstand a 5-minute porcelain wall withstand voltage test without breakdown. Its withstand voltage shall comply with the provisions of Article 2.8 of GB772. The internal pressure strength of the porcelain bushing shall comply with the following provisions
Porcelain bushing internal pressure test
4. 8. 1. 1
The porcelain bushing and porcelain parts shall be able to withstand a test of 4.25 times the design pressure for 1 minute without damage. The porcelain bushing shall be able to withstand a test of 3 times the design pressure for 1 minute without damage. The porcelain bushing shall be able to withstand a test of 4.25 times the design pressure for 5 minutes without damage. If there are special requirements, an internal pressure destruction test shall be carried out, and its value shall be agreed upon by the supply and demand parties. 4.8.2 Determination of design pressure
When the power equipment is at the highest ambient temperature and external pressure and passes the normal rated current, its maximum absolute pressure difference is the design pressure (in some cases, such as circuit breakers, the temporary pressure increase due to the breaking operation must also be considered). SF. The relationship between gas pressure and its temperature can be determined by referring to Appendix A.
4.9 The bending strength of the porcelain bushing shall comply with the following provisions JB/T 7844—1995
4.9.1 The porcelain bushing shall be able to withstand a four-way bending load test of 50% (or as agreed, but not more than 70%) bending failure load without damage. 4.9.2 The bending failure load of the porcelain bushing shall be agreed upon by both the supplier and the buyer. In addition to complying with the provisions of this standard, the porcelain bushing and porcelain parts shall also comply with the provisions of GB772 and the technical agreement of the supplier and the buyer. 4.10
Within two years from the date of delivery (i.e. the date on which the manufacturer issues the delivery notice), if the user finds that the porcelain bushing does not comply with the provisions of this standard under the conditions of compliance with this standard and the transportation, storage, installation and operation provisions approved in accordance with the prescribed procedures, the manufacturer must replace it free of charge. 5 Test method
5.1 Internal pressure test
5.1.1 General requirements for the test
For porcelain bushings: clamp or fasten the cover with valves and measuring devices to the metal accessories of the porcelain bushing, and a suitable sealing gasket should be placed between the cover and the porcelain bushing.
For porcelain bushing parts: fix the cover with valves and measuring devices in the appropriate position by an external device or by a center selector. 5.1.2 Test procedure
5.1.2.1 Endurance test procedure
The test procedure shall be in accordance with the provisions of GB775.3, and the test pressure and duration shall be in accordance with the provisions of Article 4.8 of this standard (or the rated pressure multiplied by the test pressure obtained by the relationship between pressure and ambient temperature found in Figure 1 of Appendix A, and then multiplied by the test multiple). 5.1.2.2 Test procedure shall be in accordance with the provisions of GB775.3, and the breaking pressure during the test shall be the same as that in accordance with Article 4.8 provisions (or the rated pressure multiplied by the test pressure obtained by the relationship between pressure and ambient temperature found in Appendix A Figure 1, and then multiplied by the test multiple) to determine whether it is qualified. 5.2 Bending test
5.2.1 General requirements for bending test
Bending test should be carried out without internal pressure. The porcelain sleeve should be installed on the mounting surface of the testing machine in its usual installation method. When the porcelain sleeve is composed of multiple porcelain sleeve components, the bending test can be carried out on each component. At this time, a rigid extension should be attached to the component and a load should be applied at the corresponding height to produce the corresponding test bending moment. This test is also applicable to the test of the porcelain sleeve force arm rising. When testing the porcelain sleeve component, an equal load can be applied to the free end of the porcelain sleeve to produce the specified test bending moment. This test is carried out at the upper and lower ends of the porcelain sleeve component.
The installation method of the test piece can refer to the provisions of Article 3.1 of GB775.3. 5.2.2 Test procedure
5.2.2.1 Withstand load test procedure
The four-way bending load test procedure shall be carried out in accordance with Article 3.2.2 of GB775.3, but shall be maintained for 10 seconds in each direction. 5.2.2.2 Destruction load test procedure
The test shall apply 50% (or 70%) of the load specified in Article 4.9.2 of this standard to the porcelain sleeve in four directions, with each direction 90° apart. The load shall be increased to the specified value evenly and without impact. The first three directions shall be maintained for 10 seconds. After the fourth direction reaches the test load, it shall be increased within 30 to 90 seconds until the porcelain sleeve is destroyed. Note: If the four-way bending load test has been carried out before this test, this test shall be carried out in accordance with Article 3.2.1 of GB775.3. 5.3 Other test methods adopted in this standard shall comply with the corresponding provisions of GB775.1~775.3, GB772, and JB/Z262. 6 Inspection rules
6.1 The porcelain bushing shall be inspected and accepted by the quality inspection department of the manufacturer, and the manufacturer shall ensure that all porcelain bushings delivered meet the requirements of this standard. 6.2 According to the inspection rules and test methods specified in this standard, the user has the right to inspect the quality and indicators of the porcelain bushings delivered by the manufacturer to see whether they meet the requirements specified in this standard.
6.3 The test of porcelain bushings is divided into individual test, sampling test and type test. 6.4 Individual test
JB/T7844-1995
The porcelain bushings shall be inspected one by one according to the provisions of Table 2. If it is found that a porcelain bushing does not meet any of the requirements specified in the table, then this porcelain bushing is unqualified.
Test items one by one
Test item name
Appearance quality inspection
Dimension inspection
Roughness inspection
Ultrasonic wave detection inspection
Porcelain wall withstand voltage test
Internal quality withstand test
Four-way bending load test
Geometric deviation inspection
Test according to
Article 4.10 of this standard
Article 4.1.2a of this standard
Article 4.2.3 of this standard
Article 4.3 of this standard
Article 4.7 of this standard
Articles 4.8.1.1 and 4. .8-1.2 Article
Article 4.9.1 of this standard
Article 4.2.2 of this standard
JB/Z262
Article 5.1 of this standard and GB775.3
Article 5.2 of this standard
Note: ① For porcelain bushings manufactured by the integral molding method, the power frequency voltage test of the porcelain wall is allowed to be sampled according to the number of samples for sampling test. If it fails, it should be tested one by one.
② If it can be proved that the stress caused by the design pressure is smaller than the stress caused by the maximum permanent bending moment in operation, and a pressure test has been carried out on the porcelain bushing and porcelain parts, the pressure test of the porcelain bushing or porcelain bushing components can be omitted. ③ If it can be proved that the stress caused by the maximum permanent bending moment in operation is smaller than the stress caused by the design pressure, the bending test of the porcelain bushing can be omitted. Sampling test
Ceramic bushings shall be inspected in batches. Porcelain bushings of the same model (or with basically the same structure, shape and size) made by the same process shall be considered as one batch, and the quantity of each batch shall not be specified.
The sampling test of porcelain bushings shall be carried out by randomly selecting samples from the batch after each test is qualified. The sampling rules shall be in accordance with the provisions of JB3384. This standard adopts the piece-count secondary sampling plan.
Sampling level
The sample capacity of each test can be found from the batch (N) and the selected inspection level in Table 3, and its sample capacity can be found in Table 4. Table 3
91~150
151~500
Batch and sample size code
Determination of inspection level: If there is no special provision, the inspection level of S-2 shall be adopted for the inspection of size and shape deviation, and the inspection level of S-1 shall be adopted for the other test items.
Judgment criteria
The judgment criteria for piece sampling in this standard are specified in Table 4. Sample size code
JB/T78441995
Table 4 Judgment criteria
Sample size
Judgment number
Note: ① According to the particularity of the product, the sample size of the sample size code A can be selected as "1\. When ni=1, Re1-1 is not used as the rejection judgment number. When the actual number of unqualified products d=1, repeated tests are allowed. ② Symbols in the table:
n——The sample size of the first draw of the secondary sampling plan; na—-The sample size of the second draw of the secondary sampling plan; A. Acceptance judgment number . The acceptance judgment number of the first sampling is A1 and the acceptance judgment number of the second sampling is Aa;
R. —Rejection judgment number. The rejection judgment number of the first sampling is Rest and the rejection judgment number of the second sampling is Rea;6.5.2.3
Sampling test items
The sampling test items of this standard are specified in Table 5
Sampling test items
Test item name
Waist distance inspection
Temperature cycle test
Internal pressure resistance (or damage) load test
Bending damage load Load test
Acid test
Test basis
Article 4.2.16 of this standard
Article 4.6 of this standard
Article 4.8.1.3 of this standard
Article 4.9.2 of this standard
Article 4.5 of this standard
Number of test samples
All samples drawn according to the inspection level
Samples drawn according to the inspection level among the samples after item ①
1/2 after item ② (2 when n=3)1/2 after item ②
Samples after items ③③ according to the inspection level Porcelain blocks drawn out for inspection
Test method
Article 5.1 of this standard and
Article 5.2 of this standard and
Note: ①When the sample size drawn out according to the inspection level is "1", item 4 can be omitted. ②Unless otherwise specified, one of the tests in items 3 and 4 can be selected. The type of test to be performed depends on which test can produce greater stress. For example, if it is proven that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is performed. ③When the bending test is performed on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result judgment
Each item of the sampling test is tested according to the sample capacity of each item. After the test, the result is judged according to the judgment number of each item. If the number of unqualified items in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of test items is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al1 Withstand load test procedure
The four-way bending load test procedure shall be carried out in accordance with Article 3.2.2 of GB775.3, but it shall be maintained for 10 seconds in each direction. 5.2.2.2 Destruction load test procedure
The test shall apply 50% (or 70%) of the load specified in Article 4.9.2 of this standard to the porcelain sleeve in four directions, with each direction 90° apart. The load shall be evenly increased to the specified value without impact. The first three directions shall be maintained for 10 seconds. After the fourth direction reaches the test load, it shall be increased within 30 to 90 seconds until the porcelain sleeve is destroyed. Note: If the four-way bending load test has been carried out before this test, this test shall be carried out in accordance with Article 3.2.1 of GB775.3. 5.3 Other test methods adopted in this standard shall comply with the corresponding provisions of GB775.1 to 775.3, GB772, and JB/Z262. 6 Inspection rules
6.1 The porcelain bushings shall be inspected and accepted by the quality inspection department of the manufacturer. The manufacturer shall ensure that all porcelain bushings delivered meet the requirements of this standard. 6.2 According to the inspection rules and test methods specified in this standard, users have the right to inspect the quality and indicators of the porcelain bushings delivered by the manufacturer to see if they meet the requirements specified in this standard.
6.3 The tests of porcelain bushings are divided into individual tests, sampling tests and type tests. 6.4 Individual tests
JB/T7844-1995
Porcelain bushings shall be inspected one by one according to the provisions of Table 2. If any porcelain bushing is found to fail to meet any of the requirements specified in the table, then this porcelain bushing is unqualified.
Test items one by one
Test item name
Appearance quality inspection
Dimension inspection
Roughness inspection
Ultrasonic wave detection inspection
Porcelain wall withstand voltage test
Internal quality withstand test
Four-way bending load test
Geometric deviation inspection
Test according to
Article 4.10 of this standard
Article 4.1.2a of this standard
Article 4.2.3 of this standard
Article 4.3 of this standard
Article 4.7 of this standard
Articles 4.8.1.1 and 4. .8-1.2 Article
Article 4.9.1 of this standard
Article 4.2.2 of this standard
JB/Z262
Article 5.1 of this standard and GB775.3
Article 5.2 of this standard
Note: ① For porcelain bushings manufactured by the integral molding method, the power frequency voltage test of the porcelain wall is allowed to be sampled according to the number of samples for sampling test. If it fails, it should be tested one by one.
② If it can be proved that the stress caused by the design pressure is smaller than the stress caused by the maximum permanent bending moment in operation, and a pressure test has been carried out on the porcelain bushing and porcelain parts, the pressure test of the porcelain bushing or porcelain bushing components can be omitted. ③ If it can be proved that the stress caused by the maximum permanent bending moment in operation is smaller than the stress caused by the design pressure, the bending test of the porcelain bushing can be omitted. Sampling test
Ceramic bushings shall be inspected in batches. Porcelain bushings of the same model (or with basically the same structure, shape and size) made by the same process shall be considered as one batch, and the quantity of each batch shall not be specified.
The sampling test of porcelain bushings shall be carried out by randomly selecting samples from the batch after each test is qualified. The sampling rules shall be in accordance with the provisions of JB3384. This standard adopts the piece-count secondary sampling plan.
Sampling level
The sample capacity of each test can be found from the batch (N) and the selected inspection level in Table 3, and its sample capacity can be found in Table 4. Table 3
91~150
151~500
Batch and sample size code
Determination of inspection level: If there is no special provision, the inspection level of S-2 shall be adopted for the inspection of size and shape deviation, and the inspection level of S-1 shall be adopted for the other test items.
Judgment criteria
The judgment criteria for piece sampling in this standard are specified in Table 4. Sample size code
JB/T78441995
Table 4 Judgment criteria
Sample size
Judgment number
Note: ① According to the particularity of the product, the sample size of the sample size code A can be selected as "1\. When ni=1, Re1-1 is not used as the rejection judgment number. When the actual number of unqualified products d=1, repeated tests are allowed. ② Symbols in the table:
n——The sample size of the first draw of the secondary sampling plan; na—-The sample size of the second draw of the secondary sampling plan; A. Acceptance judgment number . The acceptance judgment number of the first sampling is A1 and the acceptance judgment number of the second sampling is Aa;
R. —Rejection judgment number. The rejection judgment number of the first sampling is Rest and the rejection judgment number of the second sampling is Rea; 6.5.2.3
Sampling test items
The sampling test items of this standard are specified in Table 5
Sampling test items
Test item name
Waist distance inspection
Temperature cycle test
Internal pressure resistance (or damage) load test
Bending damage load Load test
Acid test
Test basis
Article 4.2.16 of this standard
Article 4.6 of this standard
Article 4.8.1.3 of this standard
Article 4.9.2 of this standard
Article 4.5 of this standard
Number of test samples
All samples drawn according to the inspection level
Samples drawn according to the inspection level among the samples after item ①
1/2 after item ② (2 when n=3)1/2 after item ②
Samples after items ③③ according to the inspection level Porcelain blocks drawn out for inspection
Test method
Article 5.1 of this standard and
Article 5.2 of this standard and
Note: ①When the sample size drawn out according to the inspection level is "1", item 4 can be omitted. ②Unless otherwise specified, one of the tests in items 3 and 4 can be selected. The type of test to be performed depends on which test can produce greater stress. For example, if it is proven that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is performed. ③When the bending test is performed on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result judgment
Each item of the sampling test is tested according to the sample capacity of each item. After the test, the result is judged according to the judgment number of each item. If the number of unqualified items in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of test items is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al1 Withstand load test procedure
The four-way bending load test procedure shall be carried out in accordance with Article 3.2.2 of GB775.3, but it shall be maintained for 10 seconds in each direction. 5.2.2.2 Destruction load test procedure
The test shall apply 50% (or 70%) of the load specified in Article 4.9.2 of this standard to the porcelain sleeve in four directions, with each direction 90° apart. The load shall be evenly increased to the specified value without impact. The first three directions shall be maintained for 10 seconds. After the fourth direction reaches the test load, it shall be increased within 30 to 90 seconds until the porcelain sleeve is destroyed. Note: If the four-way bending load test has been carried out before this test, this test shall be carried out in accordance with Article 3.2.1 of GB775.3. 5.3 Other test methods adopted in this standard shall comply with the corresponding provisions of GB775.1 to 775.3, GB772, and JB/Z262. 6 Inspection rules
6.1 The porcelain bushings shall be inspected and accepted by the quality inspection department of the manufacturer. The manufacturer shall ensure that all porcelain bushings delivered meet the requirements of this standard. 6.2 According to the inspection rules and test methods specified in this standard, users have the right to inspect the quality and indicators of the porcelain bushings delivered by the manufacturer to see if they meet the requirements specified in this standard.
6.3 The tests of porcelain bushings are divided into individual tests, sampling tests and type tests. 6.4 Individual tests
JB/T7844-1995
Porcelain bushings shall be inspected one by one according to the provisions of Table 2. If any porcelain bushing is found to fail to meet any of the requirements specified in the table, then this porcelain bushing is unqualified.
Test items one by one
Test item name
Appearance quality inspection
Dimension inspection
Roughness inspection
Ultrasonic wave detection inspection
Porcelain wall withstand voltage test
Internal quality withstand test
Four-way bending load test
Geometric deviation inspection
Test according to
Article 4.10 of this standard
Article 4.1.2a of this standard
Article 4.2.3 of this standard
Article 4.3 of this standard
Article 4.7 of this standard
Articles 4.8.1.1 and 4. .8-1.2 Article
Article 4.9.1 of this standard
Article 4.2.2 of this standard
JB/Z262
Article 5.1 of this standard and GB775.3
Article 5.2 of this standard
Note: ① For porcelain bushings manufactured by the integral molding method, the power frequency voltage test of the porcelain wall is allowed to be sampled according to the number of samples for sampling test. If it fails, it should be tested one by one.
② If it can be proved that the stress caused by the design pressure is smaller than the stress caused by the maximum permanent bending moment in operation, and a pressure test has been carried out on the porcelain bushing and porcelain parts, the pressure test of the porcelain bushing or porcelain bushing components can be omitted. ③ If it can be proved that the stress caused by the maximum permanent bending moment in operation is smaller than the stress caused by the design pressure, the bending test of the porcelain bushing can be omitted. Sampling test
Ceramic bushings shall be inspected in batches. Porcelain bushings of the same model (or with basically the same structure, shape and size) made by the same process shall be considered as one batch, and the quantity of each batch shall not be specified.
The sampling test of porcelain bushings shall be carried out by randomly selecting samples from the batch after each test is qualified. The sampling rules shall be in accordance with the provisions of JB3384. This standard adopts the piece-count secondary sampling plan.
Sampling level
The sample capacity of each test can be found from the batch (N) and the selected inspection level in Table 3, and its sample capacity can be found in Table 4. Table 3
91~150
151~500
Batch and sample size code
Determination of inspection level: If there is no special provision, the inspection level of S-2 shall be adopted for the inspection of size and shape deviation, and the inspection level of S-1 shall be adopted for the other test items.
Judgment criteria
The judgment criteria for piece sampling in this standard are specified in Table 4. Sample size code
JB/T78441995
Table 4 Judgment criteria
Sample size
Judgment number
Note: ① According to the particularity of the product, the sample size of the sample size code A can be selected as "1\. When ni=1, Re1-1 is not used as the rejection judgment number. When the actual number of unqualified products d=1, repeated tests are allowed. ② Symbols in the table:
n——The sample size of the first draw of the secondary sampling plan; na—-The sample size of the second draw of the secondary sampling plan; A. Acceptance judgment number . The acceptance judgment number of the first sampling is A1 and the acceptance judgment number of the second sampling is Aa;
R. —Rejection judgment number. The rejection judgment number of the first sampling is Rest and the rejection judgment number of the second sampling is Rea;6.5.2.3
Sampling test items
The sampling test items of this standard are specified in Table 5
Sampling test items
Test item name
Waist distance inspection
Temperature cycle test
Internal pressure resistance (or damage) load test
Bending damage load Load test
Acid test
Test basis
Article 4.2.16 of this standard
Article 4.6 of this standard
Article 4.8.1.3 of this standard
Article 4.9.2 of this standard
Article 4.5 of this standard
Number of test samples
All samples drawn according to the inspection level
Samples drawn according to the inspection level among the samples after item ①
1/2 after item ② (2 when n=3)1/2 after item ②
Samples after items ③③ according to the inspection level Porcelain blocks drawn out for inspection
Test method
Article 5.1 of this standard and
Article 5.2 of this standard and
Note: ①When the sample size drawn out according to the inspection level is "1", item 4 can be omitted. ②Unless otherwise specified, one of the tests in items 3 and 4 can be selected. The type of test to be performed depends on which test can produce greater stress. For example, if it is proven that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is performed. ③When the bending test is performed on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result judgment
Each item of the sampling test is tested according to the sample capacity of each item. After the test, the result is judged according to the judgment number of each item. If the number of unqualified items in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of test items is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al3 Articles
Article 4.3 of this standard
Article 4.7 of this standard
Articles 4.8.1.1 and 4.8-1.2 of this standard
Article 4.9.1 of this standard
Article 4.2.2 of this standard
JB/Z262
Article 5.1 of this standard and GB775.3
Article 5.2 of this standard
Note: ① For porcelain bushings manufactured by the integral molding method, the power frequency voltage test on the porcelain wall is allowed to be sampled according to the number of samples for sampling test. If it fails, it should be tested one by one.
② If it can be proved that the stress caused by the design pressure is smaller than the stress caused by the maximum permanent bending moment in operation, and a pressure test has been carried out on the porcelain bushing and porcelain parts, the pressure test of the porcelain bushing or porcelain bushing components may not be performed one by one. ③ If it can be proved that the stress caused by the maximum permanent bending moment in operation is smaller than the stress caused by the design pressure, the individual bending test of the porcelain bushing can be omitted. Sampling test
Porcelain bushings should be inspected in batches. Porcelain bushings of the same model (or with basically the same structural shape and size) made by the same process method are considered as one batch, and the quantity of each batch is not specified.
The sampling test of porcelain bushings should be carried out by randomly selecting samples from the batch after each test is qualified. The sampling rules are in accordance with JB3384. This standard adopts the piece-count secondary sampling plan.
Sampling level
The sample capacity of each test can be found from the batch (N) and the selected inspection level in Table 3, and its sample capacity can be found in Table 4. Table 3
91~150
151~500
Batch and sample size code
Determination of inspection level: If there is no special provision, the inspection level of S-2 shall be adopted for the inspection of size and shape deviation, and the inspection level of S-1 shall be adopted for the other test items.
Judgment criteria
The judgment criteria for piece sampling in this standard are specified in Table 4. Sample size code
JB/T78441995
Table 4 Judgment criteria
Sample size
Judgment number
Note: ① According to the particularity of the product, the sample size of the sample size code A can be selected as "1\. When ni=1, Re1-1 is not used as the rejection judgment number. When the actual number of unqualified products d=1, repeated tests are allowed. ② Symbols in the table:
n——The sample size of the first draw of the secondary sampling plan; na—-The sample size of the second draw of the secondary sampling plan; A. Acceptance judgment number . The acceptance judgment number of the first sampling is A1 and the acceptance judgment number of the second sampling is Aa;
R. —Rejection judgment number. The rejection judgment number of the first sampling is Rest and the rejection judgment number of the second sampling is Rea;6.5.2.3
Sampling test items
The sampling test items of this standard are specified in Table 5
Sampling test items
Test item name
Waist distance inspection
Temperature cycle test
Internal pressure resistance (or damage) load test
Bending damage load Load test
Acid test
Test basis
Article 4.2.16 of this standard
Article 4.6 of this standard
Article 4.8.1.3 of this standard
Article 4.9.2 of this standard
Article 4.5 of this standard
Number of test samples
All samples drawn according to the inspection level
Samples drawn according to the inspection level among the samples after item ①
1/2 after item ② (2 when n=3)1/2 after item ②
Samples after items ③③ according to the inspection level Porcelain blocks drawn out for inspection
Test method
Article 5.1 of this standard and
Article 5.2 of this standard and
Note: ①When the sample size drawn out according to the inspection level is "1", item 4 can be omitted. ②Unless otherwise specified, one of the tests in items 3 and 4 can be selected. The type of test to be performed depends on which test can produce greater stress. For example, if it is proven that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is performed. ③When the bending test is performed on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result judgment
Each item of the sampling test is tested according to the sample capacity of each item. After the test, the result is judged according to the judgment number of each item. If the number of unqualified items in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of test items is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al3 Articles
Article 4.3 of this standard
Article 4.7 of this standard
Articles 4.8.1.1 and 4.8-1.2 of this standard
Article 4.9.1 of this standard
Article 4.2.2 of this standard
JB/Z262
Article 5.1 of this standard and GB775.3
Article 5.2 of this standard
Note: ① For porcelain bushings manufactured by the integral molding method, the power frequency voltage test on the porcelain wall is allowed to be sampled according to the number of samples for sampling test. If it fails, it should be tested one by one.
② If it can be proved that the stress caused by the design pressure is smaller than the stress caused by the maximum permanent bending moment in operation, and a pressure test has been carried out on the porcelain bushing and porcelain parts, the pressure test of the porcelain bushing or porcelain bushing components may not be performed one by one. ③ If it can be proved that the stress caused by the maximum permanent bending moment in operation is smaller than the stress caused by the design pressure, the individual bending test of the porcelain bushing can be omitted. Sampling test
Porcelain bushings should be inspected in batches. Porcelain bushings of the same model (or with basically the same structure, shape and size) made by the same process method are considered as one batch, and the quantity of each batch is not specified.
The sampling test of porcelain bushings should be carried out by randomly selecting samples from the batch after each test is qualified. The sampling rules are in accordance with JB3384. This standard adopts the piece-count secondary sampling plan.
Sampling level
The sample capacity of each test can be found from the batch (N) and the selected inspection level in Table 3, and its sample capacity can be found in Table 4. Table 3
91~150
151~500
Batch and sample size code
Determination of inspection level: If there is no special provision, the inspection level of S-2 shall be adopted for the inspection of size and shape deviation, and the inspection level of S-1 shall be adopted for the other test items.
Judgment criteria
The judgment criteria for piece sampling in this standard are specified in Table 4. Sample size code
JB/T78441995
Table 4 Judgment criteria
Sample size
Judgment number
Note: ① According to the particularity of the product, the sample size of the sample size code A can be selected as "1\. When ni=1, Re1-1 is not used as the rejection judgment number. When the actual number of unqualified products d=1, repeated tests are allowed. ② Symbols in the table:
n——The sample size of the first draw of the secondary sampling plan; na—-The sample size of the second draw of the secondary sampling plan; A. Acceptance judgment number . The acceptance judgment number of the first sampling is A1 and the acceptance judgment number of the second sampling is Aa;
R. —Rejection judgment number. The rejection judgment number of the first sampling is Rest and the rejection judgment number of the second sampling is Rea; 6.5.2.3
Sampling test items
The sampling test items of this standard are specified in Table 5
Sampling test items
Test item name
Waist distance inspection
Temperature cycle test
Internal pressure resistance (or damage) load test
Bending damage load Load test
Acid test
Test basis
Article 4.2.16 of this standard
Article 4.6 of this standard
Article 4.8.1.3 of this standard
Article 4.9.2 of this standard
Article 4.5 of this standard
Number of test samples
All samples drawn according to the inspection level
Samples drawn according to the inspection level among the samples after item ①
1/2 after item ② (2 when n=3)1/2 after item ②
Samples after items ③③ according to the inspection level Porcelain blocks drawn out for inspection
Test method
Article 5.1 of this standard and
Article 5.2 of this standard and
Note: ①When the sample size drawn out according to the inspection level is "1", item 4 can be omitted. ②Unless otherwise specified, one of the tests in items 3 and 4 can be selected. The type of test to be performed depends on which test can produce greater stress. For example, if it is proven that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is performed. ③When the bending test is performed on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result judgment
Each item of the sampling test is tested according to the sample capacity of each item. After the test, the result is judged according to the judgment number of each item. If the number of unqualified items in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of test items is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al2 and
Note, ① When the sample size drawn according to the random inspection level is "1", item 4 can be omitted. ② Unless otherwise specified, one of the tests in item 3 and item 4 can be selected, and the power test depends on which test can produce greater stress. For example, it has been proved that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, then the internal pressure load test is carried out. ③ When the bending test of the upper and lower ends of the porcelain sleeve component is carried out, the number of test pieces should be doubled. 6. 5. 2. 4
Test result determination
Each item of the sampling test shall be tested according to the sample size of each item. After the test, the result shall be determined according to the determination number of each item. If the number of unqualified products in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of samples is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al2 and
Note, ① When the sample size drawn according to the random inspection level is "1", item 4 can be omitted. ② Unless otherwise specified, one of the tests in item 3 and item 4 can be selected. The power test depends on which test can produce greater stress. For example, if it is proved that the stress generated by the internal pressure load test is greater than the stress generated by the bending load test, the internal pressure load test is carried out. ③ If the bending test is carried out on the upper and lower ends of the porcelain sleeve component, the number of test pieces should be doubled. 6. 5. 2. 4
Test result determination
Each item of the sampling test is tested according to the sample size of each item. After the test, the result is determined according to the determination number of each item. If the number of unqualified products in the first sample is d,≤A1, then the item is qualified; if d,≥Re, then the item is unqualified (when the number of samples is 1, if d;=Re, it is allowed to re-draw the second sample n? for repeated testing); if Al
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