GB/T 16935.4-2011 PDF in English
GB/T 16935.4-2011 (GB/T16935.4-2011, GBT 16935.4-2011, GBT16935.4-2011)
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Insulation coordination for equipment within low-voltage systems -- Part 4: Consideration of high-frequency voltage stress
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GB/T 16935.4-2011: PDF in English (GBT 16935.4-2011) GB/T 16935.4-2011
Insulation coordination for equipment within low-voltage systems. Part 4. Consideration of high-frequency voltage stress
ICS 29.120
K30
National Standards of People's Republic of China
Low voltage system equipment with the insulation
Part 4. high frequency voltage stress considerations
(IEC 60664-4..2005, IDT)
Posted on December 30,.2011
2012-05-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
China National Standardization Administration released
Directory
Preface Ⅰ
Introduction Ⅱ
1 range 1
2 Normative references 1
3 Terms and definitions 2
4 clearance 2
5 creepage distance 5
6 solid insulation 7
7 high-frequency test 9
8 non-sinusoidal voltage 11
Appendix A (Informative) Insulation characteristics of clearances at high frequency voltage 13
Appendix B (Informative) Insulation characteristics of creepage distance at high frequency voltage 18
Appendix C (Informative) Insulation characteristics of solid insulation under high frequency voltage 21
Appendix D (Normative) Insulation test at high frequency voltage 27
Appendix E (Informative) Insulation characteristics of non-sinusoidal high frequency voltage 38
Appendix F (Informative) Insulation Size Determination Block Diagram 43
References 45
Foreword
GB/T 16935 "Insulation coordination of equipment in low-voltage systems" is divided into the following four sections.
--- Part 1. Principles, requirements and tests;
--- Part 3. The use of coating, sealing and molding anti-fouling protection;
--- Part 4. high-frequency voltage stress considerations;
--- Part 5. Determination of clearances and creepage distances not exceeding 2mm.
This section GB/T 16935 Part 4.
This section drafted in accordance with GB/T 1.1-2009 given rules.
This section uses the translation method is equivalent to using IEC 60664-4..2005 "Insulation coordination of equipment within low-voltage systems Part 4. High-frequency voltage
Stress considerations. "
This section should GB/T 16935.1-2008 "Insulation coordination with low-voltage system equipment Part 1. Principles, requirements and testing"
(IEC 60664-1..2007, IDT) and GB/T 16935.5-2008 "Insulation coordination of equipment in low-voltage systems - Part 5. Not to exceed
2mm clearance and creepage distance determination method "(IEC 60664-5..2007, IDT) with the use.
This part is proposed by China Electrical Equipment Industry Association.
This part of the National Low Voltage Equipment Insulation Coordination Technical Committee (SAC/TC417) centralized.
This section is drafted. Shanghai Electric Apparatus Research Institute.
The main drafters of this section. Zhang Jianbing, leather bag, Wu Qingyun.
introduction
Low-voltage equipment can also produce higher voltage stress. Low-voltage device voltage frequency is usually 50/60Hz, but in some cases
Under, the low pressure system may have the higher voltage frequency (400Hz) or the lower frequency (162/3Hz) and the direct current voltage. A more special one
The situation is a high-power RF transmitter. The development of such devices has led to earlier research on the insulation resistance of devices under radio frequency conditions
However, the accompanying problems of high frequency voltage stress have not been given enough attention.
Currently, high frequency operating voltages in excess of 30 kHz are being applied to low voltage equipment more and more frequently, with high levels for the megahertz
The application of frequency voltage will also be gradually expanded. These high frequency voltages are often not sinusoidal. To miniature the electrical components and get the design high
Effective, you need to reduce the size of the insulation to a very small range, resulting in high voltage stress on the solid insulation.
At the same time of increasing the voltage frequency, the degradation effect of partial discharge on the performance of insulating material is also more obvious, and the two are roughly proportional.
Thus, the effect of partial discharge on the insulation size at high voltage frequencies is much more significant than at commercial frequencies.
As the voltage and frequency of higher and smaller and smaller insulation size, and this situation will be further intensified in the future, in order to ensure operator safety
Full and equipment reliability, the voltage stress formed by the high frequency voltage up to 100MHz should be considered in the insulation coordination of low voltage equipment
Among the issues.
This section provides an overview of some of the most important data on high frequency insulation stress and explains the effects of high frequency insulation stress on insulation materials and
The size of the impact, the provisions of the clearance, creepage distance and solid insulation data. This section also gives the test of high frequency stress
method.
Low voltage system equipment with the insulation
Part 4. high frequency voltage stress considerations
1 Scope
GB/T 16935 provisions of this part of the electrical equipment performance standards for the electrical equipment clearance, creepage distance and solid insulation
Request. This section contains the electrical test method of insulation coordination.
The provisions of this section the value of the minimum clearance does not apply to the presence of ionized gas situation, the special requirements for the case will be phase
Technical Committee regulations.
This section applies to low-voltage equipment to withstand high-frequency voltage stress of the basic insulation, additional insulation and reinforced insulation. Insulation in this section
The dimensional data applies directly to the basic insulation; for reinforced insulation, the additional requirements given in IEC 60664-1 apply; This section applies to base
Clearances, creepage distances, and solids at any type of periodic voltage at wave frequencies in the 30 kHz to 10 MHz range
Determination of insulation size.
This section should be used in conjunction with IEC 60664-1 or IEC 60664-5. Through the use of the above three criteria can be made
The voltage frequency limits of IEC 60664-1 and IEC 60664-5 are raised above 30kHz.
This section also applies to IEC 60664-3 and type 1 protection when the voltage frequency exceeds 30kHz. For type 2 protection
Still under consideration.
Note 1. Size data in the frequency range over 10 MHz is under consideration.
Note 2. This section did not consider the main circuit of high-frequency radiation. In the normal use of equipment, it is generally believed that the radiation emitted to the main circuit of the high-frequency voltage formed
The interference is insignificant compared with the insulation stress, so it can not be considered.
This section applies to the application of altitude not exceeding.2000m environment, the rated voltage does not exceed the exchange of 1000V electrical equipment.
This section does not apply to the following situations.
--- In a liquid environment;
--- In addition to air outside the gas environment;
--- In compressed air.
Note 3. There may be higher voltages in the internal circuits of electrical equipment.
NOTE 4 The requirements for applications above.2000 m above sea level may be given in Table A.2 of IEC 60664-1 Annex A.
This section aims to provide guidance to the technical committee responsible for various electrical equipment standards to coordinate the requirements of each equipment so that
In the provisions of the air gap, creepage and solid insulation can achieve the purpose of insulation.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
IEC 60112..2003 Solid insulating materials compared to the tracking under the dawning index and tracking resistance index method
3 Terms and definitions
The terms and definitions given in IEC 60664-1 and the following terms and definitions apply to this document.
3.1
The approximate uniform electric field is approximatelyhomogeneousfield
When the frequency of an electric field exceeds 30 kHz and the bending radius of the conductive portion is equal to or greater than 20% of the electric gap, the electric field is
Considered as an approximately uniform electric field.
3.2
Non-uniform electric field inhomogeneousfield
When the frequency of an electric field exceeds 30 kHz and the bend radius of the conductive portion is less than 20% of the clearance, the electric field is considered as
Non-uniform electric field.
3.3
Upeak
The peak value of any type of periodic peak voltage across the insulating layer.
3.4
fcrit
The breakdown voltage of the gap starts to drop at the critical voltage frequency.
3.5
fmin
The breakdown voltage of the clearance decreases at the maximum voltage frequency.
3.6
Partial discharge voltage PD-voltage
Partial discharge start voltage Ui and partial discharge extinction voltage Ue collectively.
3.7
Electric field strength electricalfiledstrength
The voltage gradient per unit length, usually expressed in kV/mm, is denoted as E.
4 electrical clearance
4.1 General Conditions
This section applies to the electrical clearance exposed to the air. The data used to determine the size apply at altitudes of.2000 m and below only. If the sea
If the pull-out exceeds.2000m, the altitude correction factor in Table A.2 of IEC 60664-1 shall apply.
4.2 basic information
In accordance with the basic information given in Appendix A.1, if the periodic voltage-dependent, the tolerance of the gap is only affected by the voltage frequency
(See 3.1.1.2 of IEC 60664-1 or IEC 60664-5). The momentaryity can be determined in accordance with 3.1.1.1 of IEC 60664-1 or IEC 60664-5
Overvoltage size.
4.3 uniform and approximate uniform electric field
4.3.1 Approximately uniform electric field conditions
When the frequency of an electric field exceeds 30 kHz and the bend radius of the conductive portion is greater than or equal to 20% of the electrical gap,
The field is approximately uniform electric field.
4.3.2 breakdown characteristics of the test data
Appendix A.2.1 gives the following conclusions, the critical frequency fcrit drop breakdown voltage depends on the value of the gap, there is between
The following relationship.
fcrit≈0.2d MHz
(1)
Where.
d --- Clearance in millimeters (mm).
The test data given in Appendix A2.1 under uniform electric field conditions shows that under the maximum breakdown voltage of 50/60Hz
Decline of up to 20%. Breakdown voltage maximum frequency of decline was recorded as fmin.
Note. For the purpose of this section, the fmin described in Figure A.1 is set to 3MHz.
4.3.3 to determine the uniform electric field and the approximate uniform electric field clearance size
The relationship between the insulation properties of the electrical gap and the frequency of the uniform electric field exposure to atmospheric pressure in the air can be summarized as follows.
--- When the electric field frequency is greater than fcrit, the breakdown voltage decreases with increasing frequency, the maximum breakdown voltage drop of 20%;
Breakdown voltage reaches the minimum at fmin. If the frequency continues to increase after more than fmin, then the breakdown voltage will rise, and
May exceed the breakdown voltage of the labor frequency.
The above characteristics also apply to an approximately uniform electric field.
Determining the uniform electric field clearance size can be based on the value of case B in Table F.7 of IEC 60664-1 or the value of
Table 3 values; if the above values to IEC 60664-1 or IEC 60664-5 according to the requirements of 4.1.1 tolerance test.
The basis for determining the size of the electrical clearance for an approximately uniform electric field is the value of Case A in IEC 60664-1 Table F.7 or IEC 60664-5
In Table 3 values; using the above values do not need to withstand the test. However, the bending radius of the conductive portion needs to be greater than or equal to the electrical space
20% of the gap.
The following two methods to determine the size of clearance.
1. If accurate judgment is not required, the requirements of Table 5 of IEC 60664-1 and Table 5 of IEC 60664-3 may be used to ensure that the electrical room
The gap in this part of the frequency range with the ability to withstand 125% of the specified voltage.
2. For precise judgment, then.
a) If the voltage frequency is below fcrit (see Eq. (1)), the requirements of Table 3 of IEC 60664-1 and Table 3 of IEC 60664-5
Clearances have the ability to withstand 100% of the specified voltage.
b) If the voltage frequency is higher than fmin, it should be IEC 60664-1 Table F.7 and IEC 60664-5 Table 3 requirements, making the clearance
With the ability to withstand 125% of the specified voltage.
c) If the voltage frequency f is between fcrit and fmin, it shall comply with Table 606 of Table 1 of IEC 60664-1 and Table 3 of IEC 60664-5
Electrical clearance in the
(100% f-fcritfmin-fcrit ×
25%) × f (2)
Have the ability to withstand the provisions of the voltage.
In order to obtain the value of the critical frequency fcrit, the clearances are first specified in Table 3 of IEC 60664-1 and Table 3 of IEC 60664-5
Withstand voltage at 100%. And then compare the voltage frequency and the relationship between the size of fcrit to determine the above a), b), c) three cases which
Suitable species. Since the estimated value of fcrit is affected by the magnitude of the resulting electrical clearance, a second iterative estimate may be required.
Note. For further information on sizing, see appendix F.
4.4 Non-uniform electric field
4.4.1 Non-uniform electric field conditions
If the electric field frequency exceeds 30 kHz and the bend radius of the conductive part is less than 20% of the clearance, the electric field is regarded as a non-uniform electric field.
4.4.2 Partial discharge and breakdown characteristics of the test data
For non-uniform electric fields, fcrit can be approximated by the formula (1). In the case of an electric field frequency greater than fcrit, the non-uniform electric field frequency breaks down
The effect of voltage is much more pronounced than the uniform electric field. Compared to the frequency conditions, the breakdown voltage value of the decline of up to 50%.
Under non-uniform electric field conditions, the phenomenon of partial discharge must occur before the voltage has not reached the breakdown voltage. Frequent repetitive discharges
Phenomena cause a rapid drop in insulation and should therefore ensure that the size of the clearance is large enough to prevent the occurrence of partial discharges.
The test data is given in Appendix A.2.2.
4.4.3 to determine the size of the gap under non-uniform electric field conditions
When the voltage frequency value is lower than fcrit (see (1)), the size of the clearance should be IEC 60664-1 Table F.7 and IEC 60664-5
Table 3 withstand 100% of the specified voltage to determine.
When the voltage frequency is greater than or equal to fcrit, determine the size should consider the impact of voltage and frequency. Partial discharge can be triggered due to momentary overvoltage
The partial discharge should not be sustained by any steady-state voltage (see IEC 60664-1, 4.1.2.4), and should be
Use partial discharge to extinguish voltage. Figure 1 shows the relevant data and limit curves (see note).
Note 1. The data in Appendix A.2.2 applies when dimensioning.
Note. d is the electrical clearance.
Figure 1 Determine the air gap pressure (air gap, 5μm radius) under non-uniform electric field to avoid partial discharge
(Electrical clearance ≥1mm) or breakdown (electrical clearance < 1mm)
Table 1 gives the summary data for determining the insulation dimensions under non-uniform electric field. These data are only valid for the bending half
Suitable for smaller diameters. In practical applications, the bending radius of the conductive portion of the electric field should be less than 20% of the electrical clearance.
Note 2. For more information, see Appendix F.
Table 1 under non-uniform electric field at atmospheric pressure under the minimum air gap
a For values with voltage values between the tables, interpolation is possible.
b Data for Upeak less than 0.6 kV are not yet available.
5 Creepage distance
5.1 Test data
The data given in Appendix B considers the effect of voltage frequency on the creepage breakdown voltage.
B.2 describes the test conditions required for the test carried out and the materials used in the test.
B.3 lists the test data. It can be seen that both the partial discharge voltage and the breakdown voltage are significantly affected by the voltage frequency.
5.2 determine the creepage distance
Figure 2 shows the measurement data for three different frequency ranges (100kHz and below, 1MHz and below, 3MHz and below) and
Limit curve. Table 2 summarizes the determination of creepage distances. Data for the remaining frequency ranges can be obtained by linear interpolation. These data are suitable
For pollution level 1.
Note 1. Due to the formation of high frequency voltage partial discharge phenomenon is too long will cause great damage to the basic materials, in determining the creepage distance, B.3
Partial discharge voltage data in the applicable.
The test results in reference [5] show that when pollution levels 2 and 3, the creepage distance can be multiplied by the creepage distance at pollution level 1
The last coefficient derived. Pollution degree 2 multiplier factor of 1.2, Pollution degree 3 multiplier factor of 1.4.
The data in Table 2 does not consider the effect of the tracking phenomenon. To consider this effect, reference should be made to IEC 60664-1 or
IEC 60664-5, if the values in Table 2 of this part are less than the relevant values in Table 4 of IEC 60664-1 or IEC 60664-5, the latter
Prevail.
These data apply to all materials that may be damaged by thermal effects. For some materials that are not damaged by thermal effects (such as ceramics), press
Chapter 4 of this part determines the clearance.
Note 2. For more details on the determination of size, see Appendix F.
Note. d is the creepage distance.
Figure 2 Determination of creepage distance to avoid partial discharge (creepage distance ≥1mm) or breakdown (creepage distance < 1mm)
Table 2 Minimum ranges of creepage distances over different frequency ranges
The data given in table a for creepage distances apply for pollution class 1. For Pollution Level 2 and Pollution Level 3 multiplier factors of 1.2 are available
And 1.4.
b The values between the various columns can be linearly interpolated.
6 solid insulation
6.1 General Considerations
Solid insulation ensures that its breakdown strength is at least an order of magnitude greater than the former when compared to the air gap exposed to air. however
In practice, solid insulation of high breakdown field strength is not great.
Note. Appendix C.1 details the mechanism of lowering or even breakdown of insulation performance under low field conditions.
6.2 Influencing factors
When the electric field frequency is 1MHz, the short-time breakdown field strength can be reduced to 10% of the breakdown field strength value under the working frequency condition. Even if the electric field frequency
Up to 100MHz, breakdown field will not be lower.
NOTE. Appendix C.2 gives a description of the high frequency breakdown characteristics.
In general, the dielectric strength of solid insulation will be further reduced by the influence of humidity and temperature, especially in the case of high-frequency voltage;
The pre-test pretreatment in 7.3 considered this effect.
Based on the above characteristics, solid insulating materials used in high-frequency applications should not be exposed to environments with relative humidity greater than 92% for prolonged periods of time.
Some materials (such as glass, ceramics) are not affected by humidity, so they are not subject to the above restrictions.
The breakdown strength of solid insulation is a function of material thickness. The breakdown strength of an extremely thin film is comparable to the thickness
The breakdown strength of a 0.7 mm specimen is an order of magnitude higher, so any size determined from the solid insulation thickness should take into account the insulation
Effect of thickness on breakdown field strength.
Appendix C.2 describes the temperature on the breakdown voltage, temperature is an important factor in determining the size and test should be given
Give full consideration.
Partial discharge phenomenon under high-frequency voltage will show a high repetition rate of partial discharge pulse, so in the event of partial discharge phenomenon, will be
Unable to predict the service life of solid insulation.
6.3 to determine the size of solid insulation
The following method may replace the high-frequency test described in Chapter 7 to determine the solid insulation size. If the electric field strength is approximately uniform, the correlation value does not exceed
The values given in Equation 3 and Figure 3 are given, and there is no void or air gap between the solid insulation, so that the method can operate at a voltage of no more than
10MHz occasions apply. If the above conditions are not met, it should be required by Chapter 7 of high-frequency voltage test.
If the electric field is approximately uniform (see the note below), the following method of determining the solid insulation dimensions applies. For solids with thickness d1 ≥ 0.75mm
Insulation, the peak electric field intensity E should not exceed 2kV/mm. For solid insulation with a thickness of d2 ≤ 30 μm, the peak value of electric field strength does not
Should exceed 10kV/mm. For d1> d> d2, the electric field strength corresponding to a certain thickness d should be obtained by the interpolation of equation (3)
(See Figure 3).
Note 1. The electric field is considered to be approximately uniform if the electric field strength offset does not exceed 20% of the average of the electric field strength.
Note. E is the field strength.
Figure 3 according to equation (3) to determine the size of the solid insulation allows the electric field strength
In determining the solid insulation size, if the value of the electric field strength is used, the electric field must be approximately uniformly distributed and free of voids
Air gap. If the field strength can not be calculated using the above formula (uneven electric field distribution) or if the peak value is greater than the value in equation (3) or (3) or in the electric field
Of the hole or air gap can not be eliminated, or the voltage frequency is greater than 10MHz, high frequency voltage partial discharge test should be carried out or tolerance test. Such as test
Consider the short-term stress tolerance test, if long-term stress to consider the partial discharge test, the test according to IEC 60664-1 in 3.3.3.2.2.
7 high-frequency test
7.1 basic requirements
The following tests were conducted at the applied voltage frequency.
--- High-frequency AC voltage test to verify the gap and solid insulation short-term dielectric strength;
--- Verify high-frequency voltage reaches steady state when there is no partial discharge occurs.
Due to the large capacitive load present at high frequencies, the high-frequency tests are mainly conducted on components and equipment modules. If you need to become
Equipment for additional high-frequency test, then according to IEC 60664-1 4.1.2 requirements at the power frequency voltage.
7.2 Test voltage source
Appendix D.1 gives the requirements of the test voltage source.
7.3 Pre-treatment
Unless otherwise specified by the Technical Committee, the test should be performed on a new test sample. The sample is subjected to temperature and humidity
The purpose of treatment is.
--- Simulate the normal working conditions of the most harsh conditions;
--- Exposure equipment under normal conditions did not appear defects.
The preprocessing method described in 4.1.2.1 of IEC 60664-1 is also suitable for high frequency testing.
7.4 high-frequency breakdown test
This test is similar to the power frequency high voltage test (see 4.1.2.3 of IEC 60664-1).
7.4.1 Test methods
High-frequency tolerance by the equipment temperature and environmental conditions, the test should be in the normal operation of the equipment may encounter the most harsh conditions
Including the temperature rise caused by normal operation of the equipment. Test duration of 1min.
7.4.2 Test results
Breakdown should not occur during the test. After the test, the specimen surface should not leave visible damage (burning marks, melting, etc.).
7.5 high-frequency partial discharge test
7.5.1 General Considerations
IEC 60270 describes the general method of partial discharge tests. For low-voltage equipment, partial discharge test, see IEC 60664-1
4.1.2.4 and Appendix C apply, but for the partial discharge test of high-frequency voltage, the test tools and test methods should be modified according to this section.
In order to minimize damage to the sample, the partial discharge test should be carried out according to strict procedures, the test voltage should be in the partial discharge starting power
Pressure range. The lowest level of partial discharge (usually less than 10pC) should be specified to determine the failure criteria. View partial discharge voltage extinction
Difficult to determine accurately, and other factors such as temperature and humidity, and these factors are often overlooked in the test, the partial discharge voltage
A safety factor of F1 = 1.2 shall be included. The partial discharge extinguishment voltage shall be the product of the factor and the maximum value of the periodic peak voltage (see
IEC 60664-1 4.1.2.4); For reinforced insulation, due to its need to consider more dangerous, so the partial discharge voltage to be exponentially multiplied by a
Safety factor F3 = 1.25. (See 4.1.2.4 of IEC 60664-1)
Partial discharge test is mainly for components. However, it is also possible to test complete plants, in this case for partial discharge sources
The positioning of the more difficult, the measured partial discharge level as a function of the location within the device. In type testing, partial discharge test the main test
Check the insulation system design is appropriate, the choice of insulating material is reasonable, the manufacturing process is normative. These tests are in the equipment design process
Can also play a role. Through the sampling and routine inspection, the entire manufacturing process can be inspected, which plays an important role in ensuring product quality.
Due to the application of high-frequency test voltage in the test, it is required to shield the test system with a conductive housing to avoid interference with other nearby electrical
Subsystems interfere with each other, in general, this shielding measures in the partial discharge measurement sufficient to meet the interference level requirements.
7.5.2 Test methods
In view of the sample is extremely vulnerable to high frequency voltage conditions, the test voltage should be increased as soon as possible, and to avoid the test voltage jump. high
The noise level in the frequency partial discharge test is usually significantly higher than the noise level in the power frequency test.
7.5.3 Test Equipment
It is difficult to measure the partial discharge ratio under high-frequency voltage conditions under ordinary conditions because the test voltage and the partial discharge signal are spectrally
There is overlap, which requires the proper way to separate (filter). Because the test voltage frequency range of a wide range of changes, it is necessary to use tuning ultra-narrow
With filter. The center frequency of these filters should be adjusted to the frequency of the test voltage. Non-sinusoidal test voltage signal from partial discharge signal
Separated out is particularly difficult, so this section does not recommend such tests. In determining the partial discharge intensity, the use of digital storage oscilloscope and a combination
Band stop filter to suppress high frequency test voltage.
Appendix D.2 shows several examples of partial discharge test circuits for high frequency voltages. Partial discharge testing consists of fast sampling
Digital storage oscilloscope digital integrator to complete.
7.5.4 Test circuit
Partial discharge measurement is achieved by detecting the partial discharge current. A measuring resistor Rm in series with the test. Put this resistor on both ends
The voltage drop across a band-stop filter is applied...
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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