GB/T 8554-1998 Measurement methods and test procedures for transformers and inductors for electronic and communication equipment
Some standard content:
GB/T8554—1998
This standard is the first revision of the national standard GB/T8554-1987 "Test methods and test procedures for transformers and inductors for electronic and communication equipment". This revision of this standard adopts the international standard IEC 1007:1994 "Measurement methods and test procedures for transformers and inductors for electronic and communication equipment". In this way, by making our standards equivalent to international standards, we can adapt to the needs of international trade, technical and economic exchanges and the development of international standards as soon as possible. This standard was first issued in 1987 and revised in November 1998. This standard was first revised in July. This standard was proposed by the Ministry of Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the National Technical Committee for Standardization of Magnetic Components and Ferrite Materials. This standard was drafted by the Standardization Institute of the Ministry of Electronics Industry. The drafters of this standard are Shi Guilan, Yin Zulun, Liang Mingjun, Niu Chunsheng, and Cao Zhenhe. ..comGB/T8554—1998
IEC Foreword
1) IEC (International Electrotechnical Commission) is a worldwide standardization organization composed of national electrotechnical committees (IEC National Committees). The purpose of IEC is to promote international cooperation on standardization issues in the field of electrical and electronic engineering. To this end, Among other activities, the IEC publishes International Standards. The preparation of International Standards is undertaken by Technical Committees, and any IEC National Committee with an interest in the subject matter may participate in the preparation of International Standards. Any international, governmental and non-governmental organization in contact with the IEC may also participate in the preparation of International Standards. The TEC maintains a close cooperative relationship with the International Organization for Standardization (ISO) under conditions agreed upon between the two organizations. 2) Formal IEC resolutions or agreements on technical issues are prepared by technical committees in which national committees with a particular interest in these issues participate, and represent international consensus on the issues involved as far as possible. 3) These resolutions or agreements are published in the form of standards, technical reports or guidelines, and are recommended for international use and, in this sense, are recognized by the National Committees.
4) In order to promote international unification, each IEC National Committee has the responsibility to make its countries and regions adopt IEC standards as far as possible. Any differences between IEC standards and corresponding national or regional standards should be indicated in the national or regional standards. This International Standard IEC1007 was prepared by IEC Technical Committee 51 (Magnetic Components and Teflon Materials). This second edition of the standard cancels and replaces the first edition of 1990 and Amendment 1 and Amendment 2 (Published in 1993) and constitutes a technical revision.
This edition of this standard is based on the first edition of IEC 1007 and Amendment 1, Amendment 2 and the following documents. IEC draft
51(C0)309
Voting report
51(CO)312
The full details of the voting for the approval of this standard can be found in the voting report indicated in the table above. 1 Scope
National Standard of the People's Republic of China
Test methods and test procedures for transformers and inductors for electronic and communication equipment
Transformers and inductors for use in electronic and telecommunication equipmentMeasuring methods and test proceduresGB/T 8554--1998
idt IEC 1007:1994
Replaces GB/T 8554-19R7
This standard specifies the measuring methods and test procedures for transformers and inductors for use in electronic and telecommunication equipment. These measuring methods and test procedures may be included in any specification of such components, in particular, that part of the specification that constitutes the IEC electronic component quality assessment system (IECQ system).
2 Referenced standards
The provisions contained in the following references constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. IEC27 Alphabetical symbols used in electrical engineering
IEC44-4t1980 Instrument transformers Part 4: Measurement of partial discharge IFC50 International Electrotechnical Vocabulary (IEV)
1EC 68-1:1988 Environmental testing Part 1: General principles and guidelines Amendment 1 (1992) IEC68-2: Environmental testing, Part 2, Test 1EC 68-2-1:1990 Environmental testing, Part 2; Test IEC 68-2-2:1974 Environmental testing, Part 2. Test Test 4: Low leakage: Peak Amendment 1 (1993)
Test B: High temperature Amendment 1 (1993)
IFC 68-2-3:1969 Environmental testing, Part 2: Test ~ Test CA: Steady state damp heat
IEC IEC 68-2-6:1982 Environmental testing, Part 2; Tests — Test Fc and guidance: Vibration (sinusoidal) IEC 68-2-7: 1983 Environmental testing, Part 2: Tests — IEC 68-2-10:1988 Test Ca and guidance: Constant acceleration Amendment 1 (1986) Tests — IEC 68-2-13:1983 Environmental testing, Part 2: Tests — Environmental testing, Part 2, Tests IEC 68-2-14:1984 Environmental testing, Part 2: Tests — IEC 68-2-20:1986 Environmental testing, Part 2: Tests — IEC 68-2-21:1986 Environmental testing, Part 2: Tests — IEC 68-2-22:1986 Environmental testing, Part 2: Tests — IEC 68-2-23:1986 Environmental testing, Part 2: Tests — IEC 68-2-24:1986 Environmental testing, Part 2: Tests — IEC 68-2-25:1986 Environmental testing, Part 2: Tests — IEC 68-2-26:1982 Environmental testing, Part 2: Tests — IEC 68-2-27:1983 Environmental testing, Part 2: Tests — IEC 68-2-28:1984 Environmental testing, Part 2: Tests — IEC 68-2-29:1984 Environmental testing, Part 2: Tests — IEC 68-2-30:1984 Environmental testing, Part 2: Tests — IEC 68-2-31:1984 68-2-17:1978
Environmental testing, Part 2, Tests
IEC 68-2-20;1979 Environmental testing, Part 2: TestsIEC 68-2-21:1983
IEC 68-2-27:1987
Test N: Temperature change warning revision 1 (1986)
Test Q, sealing revision 4 (1991)
Test T: welding: revision 2 (1989)
Static revision 2
Environmental testing, Part 2; Test I
--Test U lead-out terminals and integral mounting strength (1991) revision 3 (1992)
Environmental testing, Part 2: Tests
Test Ea and lead-out terminals, shock
FEC IEC 68-2-29:1987
Environmental testing, Part 2: Test - Test Eb and guidance: Impact IEC 68-2-30:1980 Environmental testing, Part 2: Test - Test Db and guidance: Thermal cycle (12+12 h cycle) Revision 1 (1985)
National Quality and Technical Supervision Bureau Approved on November 17, 1998 Implemented on July 1, 1999
CB/T 8554-1998
IEC 68-2-42:1982 Environmental testing, Part 2: Test - Test Kc Sulfur dioxide test for contacts and connectors IEC 68-2-45:1980
Environmental testing, Part 2: Test - Test XA and guidance: Immersion in cleaning agents IEC 68-2-52:1984
Environmental testing, Part 2: Test 1—Test Kb: Alternating salt spray test method (sodium chloride solution) IEC 68-2-58:1989
Spherical environment testing, Part 2: Test Test Td: Solderability of surface mounted optical devices (SMDs), resistance to melting and resistance to soldering heat of metal coatings
IEC270:1981 Measurement of two-part effective current
IEC367-1:1982 Inductors for telecommunications and magnetic cores for transformers Part 1: Methods of measurement Amendment 1 (1984) (1992)
1EC551.1987 Determination of sound levels of transformers and reactors IEC617 Graphical symbols for use in drawings
IEC651:1979 Sound level meters Amendment 1 (1993) IEC95-2 Fire hazard testing Part 2: Test methods IEC695-2-2:1991, Fire hazard testing Part 2: Test methods Section 2 Needle flame test Amendment 2
IEC 695-2-4/0+1991
Fire hazard testing Part 2: Test methods Section 4/Page 0 Scattered and premixed flame test methods
IEC 695-2-4/1:1991
ISO3:1973 Priority number
ISO 497:1973
Fire hazard testing
Part 2: Test methods Section 4/Page 1, Nominal 1 kW premixed measuring flame and guidance
Preferred number series
Preferred number system Guide to the selection of preferred number systems including rounded preferred number systems ISO 1000:1992 [
Construction of international units and their multiples and use of certain other units 3 Terminology
In addition to the terms used in IEC 50, this standard also uses the following terms 3.1 Component
The components mentioned in this standard refer to transformers and inductors. 3.2 Peak working voltagepeak working voltageThe maximum instantaneous insulated voltage that can be withstood by the insulation of a winding under the operating circuit conditions. 3.3 Pulse waveform parameters (see Figure 1) a) Peak pulse amplitude Unpeak pulse amplitude The peak pulse amplitude refers to the maximum value extrapolated through the smooth curve at the top of the pulse, excluding the initial "spike" or "overshoot" whose duration is less than 10% of this pulse duration. b) Pulse duration ta pulse duration The pulse duration refers to the time between the first and last moments when the pulse amplitude is equal to 50% of the peak pulse amplitude. c) Pulse rise time t pulse rise time The pulse rise time refers to the time between the first 10% and 90% of the peak pulse amplitude reached by the pulse amplitude, excluding unnecessary or irrelevant parts of the waveform.
d) Pulse fall time tr pulse fall time Pulse fall time refers to the time between the last instant when the pulse amplitude reaches 90% of the peak pulse amplitude and the instant when the following pulse amplitude reaches 10% of the peak pulse amplitude, excluding unnecessary or irrelevant parts of the waveform. Note: The value of the fall time must be close to 10% of the peak pulse amplitude. The point of the fall time defined above can be replaced by the last instant when the pulse amplitude reaches 81% of the peak pulse amplitude.
e) droop
Drop refers to the difference in pulse amplitude (expressed as a percentage of the peak pulse amplitude) between the peak pulse amplitude and the extrapolated line of the smooth curve of the pulse top (excluding the initial "spike" or "overshoot") on the true line passing through the point defined as the pulse fall time. f) pulse crest
The pulse crest refers to the maximum amplitude of the pulse. g) overshoot
Overshoot refers to the value of the pulse peak exceeding the peak pulse amplitude. Overshoot is expressed as a percentage of the peak pulse amplitude. h) Backswing
Backswing refers to the maximum amplitude of the reverse pulse, that is, the part that crosses below the zero amplitude level. The backswing is expressed as a percentage of the peak pulse amplitude.
i) Turn backswing
Backswing refers to the maximum amplitude of the rotation after the backswing. The backswing is expressed as a percentage of the peak pulse amplitude. j) Recovery time
Recovery time refers to the time interval from the end of the pulse falling time to the moment when the pulse amplitude finally reaches 10% of the peak pulse amplitude. k) Pulse repetition frequency Pulse repetition frequency refers to the average number of pulses per unit time. The pulse repetition frequency has nothing to do with its measurement time range. 3.4 Quality factor (Q) factor
The quality factor refers to the ratio of the energy stored in a specified winding during a cycle at a specific frequency to the energy consumed. The quality factor is expressed in the form of a series or parallel connection of the reactance component and the energy-consuming resistance component. =1-Rise time
Pulse top
-Pulse hold time
-Rise time
-Fall time
Recovery time
Note: In order to clearly illustrate the term drop, the points at 80% and 10% of the peak pulse amplitude are used when drawing the adjacent line between the pulse top and the pulse. Figure 1 Pulse waveform parameters
3.5 Harmonic distortion Harmonic distortion refers to the square root of the sum of the squares of all harmonic voltages within the seventh and seventh harmonics (excluding the fundamental), expressed as a percentage of the fundamental wave or in decibels relative to the fundamental wave.
3.6 Maximum winding temperature Maximum winding temperature refers to the average temperature rise of any winding of the component under full load when thermal stability is achieved plus the specified maximum ambient temperature.
3.7 Voltage-time product rating The voltage-time product rating refers to the product of the pulse voltage amplitude and the pulse duration. During this period of time, the nonlinear value of the current does not exceed the specified value.
GB/T8554—1998
3.8 Background (acoustic) noise Background noise refers to the noise measured at the measurement point minus the noise generated by the test element. 3.9 Compass safe distance The compass safe distance refers to the distance from the rotation center of the test magnetometer or compass to the nearest point on the surface of the test element. The magnetic deflection at this distance is limited to the specified value. 3.10 Duty ratio The duty ratio refers to the ratio of the pulse duration to the cycle time. 3. 11 Current transformer parametersa) Burden
The load is the parameter of the circuit connected to the secondary winding of the current transformer, which determines the active power and reactive power at the secondary end. The load is expressed by the total impedance of the effective resistance and reactance, or by the total volt-ampere value and power factor of the specified current value and the specified frequency value. b) Current transformation ratio The current transformation ratio is the ratio of the effective value of the primary current to the effective value of the secondary current under specified conditions. c) Phase angle
The phase shift angle is the angular displacement between the primary current and the secondary current of the transformer. When the secondary current leads the primary current, the phase shift angle is a positive number.
d) Ratio error
The ratio error is the difference between the measured value K of the current transformation ratio and its nominal value K, divided by the measured value K. The relative error is expressed as a white fraction: K = × 100%
Ratio error =
3.12 Electrostatic screen electrostatic screen refers to the conductive screen inserted between windings. When the screen is grounded, it will greatly reduce the transmission of harmful signals to other windings through the capacitance between windings.
3.13 Safety screen safety screen
Safety screen refers to the conductive screen inserted between windings. When the screen is grounded, it can effectively prevent the fault current from flowing between those windings even if the insulation is damaged.
3.14 Polarity (applicable to single-phase windings) Polarity of single-phase windings refers to the polarity of one end of a winding being the same as the polarity of another winding end. If the other ends of the windings are connected to form a common end, and a sinusoidal voltage is applied to the transformer (or inductor), the induced voltage between each end and the common end must rise through zero at the same moment. 3.15 Uniformly-insulated winding Uniformly-insulated winding means a winding whose insulation to earth is designed to withstand the dielectric strength test. The voltage value applied should be appropriate to the insulation at the high voltage end.
3.16 Graded-insulated winding Graded-insulated winding means a winding whose insulation to earth is graded from the value of the high voltage wax to a lower value at the low voltage end. Such a winding should withstand the dielectric strength test. The voltage value applied should be appropriate to the insulation at the low voltage end. 4 Test procedure
4. 1 Test and measurement conditions
Unless otherwise specified, all tests shall be carried out under the standard atmospheric conditions specified in IEC 68-1. When there is a requirement for the components to reach temperature stability, the test shall comply with the requirements of 4.8 of IEC 68-1. Unless otherwise specified in the detailed specification, all voltages and currents shall be sinusoidal; their values shall be effective values (r.II.8.),The multiphase power supply is assumed to be balanced.
GB/T 8554—1998
The "contents to be specified" mentioned in this chapter when describing the test methods should be specified in the detailed specifications related to the components. For components expected to be used at sufficiently high frequencies, the length of the test leads becomes a significant issue, so the detailed specifications should also specify the fixtures used with the components.
4.1.1 Measurement errors
The limit values quoted in the detailed specifications should be absolute values. When the measurement results are evaluated against the limit values of the specification, the tolerance values acting on the actual measurement system should be taken into account. When the tolerance values for the corresponding equipment conditions or instrument errors have been specified, this tolerance value is an additional minimum requirement.
4.1.2 Alternative test methods
The test and measurement methods specified in the relevant specifications should not be used as the only methods to be adopted (existing special equipment and good dynamic test equipment can also be used). However, the tester shall satisfy the user or the relevant competent authority (see Note 1) that the alternative method used can produce results equivalent to those of the standard method (see Note 2). In the event of a dispute, the specified method shall be used for arbitration and delivery. Alternative test methods shall not appear in the detail specification.
1 For example, the national inspection and testing body within the IECQ system. The term "equivalent" means that the characteristic value determined by the alternative method and the tolerance caused by the measurement by the alternative method are within the specified limits when measured by the specified method:
4.2 Visual inspection
The visual inspection shall be carried out under normal factory conditions and without visual inspection auxiliary equipment. The processing quality, marking and surface treatment shall comply with the requirements.
Note that if special lighting and visual inspection auxiliary equipment are required for the acceptance of special components (such as very small components), these may be specified as additional tests in the relevant detailed specification.
4.2.1 Location of safety shields
Note: Sometimes "isolation shield" is used instead of "safety shield". To verify the position of the safety screen relative to the phase winding. Procedure: The safety screen, when arranged and positioned, shall be verified before being covered by the following winding. The safety screen shall comply with the following requirements:
a) The safety screen shall be wound around the entire shielded cable group so that the overlap width between the end and the beginning is not less than the value specified in the detailed specification:
b) The safety screen shall be properly insulated so that it does not constitute a short-circuit group: c) The safety screen shall have a plane sufficient to extend along the shielded winding to prevent direct contact between the windings Note: The shield used as a toroidal transformer may consist of several conductive strips, with each turn overlapping the adjacent turns by not less than 5% of the bandwidth. Contents to be specified:
a) Minimum overlap width.
4.2.2 Solder joint quality
Note: A good solder joint is a solder joint with good electrical contact and sufficient mechanical strength between the connected parts. An example of a good solder joint is shown in Figure 2. Defective solder joints are shown in Figure 3.
Purpose: To check the quality of all solder joints. Procedure: All solder joints should be checked to ensure that they meet the following requirements: 8) The solder joints have good wetting as evidenced by the free flow of solder and the wetting of the lead-out terminals b) The solder joints are flat and clear without spikes;
c) The solder joints are bright and shiny;
d The solder joints have no rough scars
e) The solder joints should have a concave surface, and the outline of the wire is visible below the solder joint surface #f) During soldering, the solder joints have not been moved (the "skinning effect" of the moved solder joints is shown in Figure 3 (a));..comGB/T 8554 . -1998
g) The solder joint should not be a "dry point" (that is, there should be no obvious boundary at the edge of the solder joint where the wire is connected or there should be a large contact angle between the solder joint and the wire (see Figure 3(b));
h) The solder joint should not cause residual stress in the lead wire at the lead end (see Figure 3(c))i) There should be no "sucking" that is, the connecting wire should not cause the solder to be sucked into the multi-strand wire due to overheating, see Figure 3()). Figure 2 Examples of good solder joints
(α) Moved solder joint
(c) Solder joint with mechanical stress
4.3 Dimension measurement and inspection procedures
The dimensions should be inspected in accordance with relevant specifications.
4.4 Electrical test procedureWww.bzxZ.net
4.4.1 Winding resistance
4.4.1.1 DC resistance of winding
Figure 3 Example of defective solder joints
(b) Dry solder joints
Return the material to the wire strands to make them flexible
GB/T 8554—1998
Date: To test the DC resistance between windings or specified lead-out terminals. Procedure: The resistance shall be measured using the applicable method. When required by the detailed specification, the ambient temperature 6 (℃) should be measured, and the resistance measurement result R(a) should be converted to the resistance value Ro(n) corresponding to 20℃ as follows: Res20
Where: K is a constant related to the thermal coefficient of resistivity. In this standard, the K value of copper is 234.5 and the K value of aluminum is 228.1; Rm is the measured resistance value, 0
—…ambient temperature,
To: For safety reasons, the capacity of the short-circuited winding that generates high voltage when the current is interrupted should be considered. Contents to be specified:
) The lead-out terminals to be measured between each other: b) Whether the measured results need to be converted to the resistance value at a temperature of 20℃. If conversion is required, the K value should be given for the non-copper and non-aluminum materials used.
1 The selection of the test method should be determined based on the convenience of the test operation and the required accuracy. The accuracy of the equipment should be at least 10 times higher than the accuracy required by the test. 2 The measured current shall not be so great as to cause incandescence or produce a noticeable magnetizing effect on the components. 4.4.1.2 Continuity
Purpose: To verify the continuity of specified windings. Procedure: Continuity shall be determined using a suitable DC or AC voltage or current source and a suitable indicator. Contents to be specified:
Test winding.
1 The base current shall not be so great as to produce a noticeable magnetizing effect on the components. 2 During the test, attention must be paid to the high voltage that may be generated by windings with high inductance values. 3 When there are parallel branches, such as multi-phase or multi-phase components, it may be necessary to check the DC resistance to ensure that the branch being checked is not affected by the shunt. 4.4.2 Insulation test
4.4.2.1 Electric strength test
Purpose: To verify that the insulation of uniformly insulated windings and the insulation of the low-voltage ends of graded insulation windings meet the requirements. Note
1 This test is not applicable to the insulation of the high-voltage ends of graded insulation, or those designed to be grounded at one point. The insulation of the high-side end of this winding shall be tested with the corresponding induced voltage test (see 4.4.2.2 Special test conditions 6)). In some cases, it may be necessary to prove 4.4.2.2 During the induced voltage test (see b) of the special test component, the insulation of the low-voltage side of the graded insulation system is satisfactory.
Procedure: Unless otherwise specified, the test voltage value shall be selected from the following table. The selected test voltage shall be applied between the parts of the component that are specified to be insulated from each other. All windings shall be short-circuited. The windings and shields of the insulation system one shall be connected to the frame, core and grounded, while the windings and shields of the other side shall be connected together. The test voltage shall be increased from zero to the specified value at an appropriate rate (but not exceeding 2kV/s) and maintained for a specified time (unless breakdown occurs), and then reduced to zero at the same rate. In liquid-filled components, except for those components designed to work only on one plane and marked as such, about half of the test samples shall be tested with the leads facing upward and the leads of the other half of the components shall be tested downward. If this test requires testing under specified environmental conditions, unless otherwise specified (see the content of IEC68 environmental tests), the components shall be kept under specified conditions for at least 6 hours. The test components shall not have burning, breakdown or damage, and ionization shall not be used as a criterion for breakdown. The current shall not exceed the specified value. Contents to be specified: a) Leads to be tested between each other b) Test voltage: GB/T 8554--1998
c) frequency of the AC test current (if different from that specified in Table 1); d) duration of the test;
e) maximum leakage current (if specified).
3 If a breakdown occurs during the test, it will be detected initially by a sporadic and intermittent increase in the leakage current, followed by a periodic increase in the leakage current to a higher constant value, which, on many electrical strength test equipment, is accompanied by a partial or total disappearance of the voltage. This type of breakdown may be due to partial breakdown in ionized air and weak insulation parts, followed by a sudden total breakdown in the form of a nebula or arc. The dielectric strength test voltage may be dangerous. Special caution must be exercised during this test. 4
Table 1 Dielectric strength test voltage
Peak working voltage
>25~50
>50~100
>100--175
>175~700
4.4.2.2 Induced voltage test
AC test voltage, 45~65 Hz
V(rms)
2.9×peak working voltage
1.4×peak working voltage+
DC test voltage
4Xpeak working voltage
2Xpeak working voltage+
Purpose: To verify that there is sufficient insulation between turns and layers of transformers and inductors, and to verify that there is sufficient insulation at the high-voltage end of the graded insulation group.
Special Test Conditions
The following special test conditions apply:
a) Windings with uniform insulation shall be tested as specified in Procedure 1, Procedure 2 or Procedure 3, as applicable. Any point on the winding may be earthed during the test as specified; b) Windings with graded insulation shall be tested as specified in Procedure 1, Procedure 2 or Procedure 3, as applicable. Any point on the winding may be earthed or raised to a specified voltage above earth potential during the test. The induced voltage test shall be carried out by applying the voltage in a direction such that the high voltage end of the winding is raised to the corresponding peak test voltage given in Procedure 4.4.2.1. If the specified voltage above earth potential is an alternating voltage, the frequency of this alternating voltage shall be the same as the frequency of the coil voltage. NOTE 1: For the passband, it is not permitted for any winding to be "floating", i.e., to remain disconnected at both ends, when the induced voltage test is carried out. Procedure 1 applies to transformers and inductors intended to be excited sinusoidally. The specified test voltage shall be applied to the specified winding, which shall not be less than twice the rated voltage and whose frequency shall not be less than twice the minimum rated frequency. The time and manner of applying the voltage shall comply with the provisions of the detailed specification. Procedure 2: Applicable to transformers and inductors excited by pulses. The pulse amplitude specified in the test voltage shall not be less than twice the rated pulse amplitude, the specified pulse repetition rate shall not be less than 25% of the highest rated pulse repetition frequency, and the specified pulse duration shall not be less than 25% of the rated maximum pulse duration. The pulse duration applied to the general winding shall not be greater than 50% of the rated pulse duration. The time and manner of applying the voltage shall comply with the provisions of the detailed specification. Procedure 3: Applicable to transformers and appliances excited by non-sinusoidal periodic waves, such as transformers and inductors excited by power supplies working with switching type semiconductors.
A specified sinusoidal peak test voltage shall be applied to the specified winding, which shall not be less than twice the maximum rated peak voltage of the input voltage wave and whose frequency complies with the values specified below. The time and manner of applying the test voltage shall comply with the provisions of the detailed specification. The test rate should generally be such that its period is greater than the effective shortest half-period of the expected working waveform of the component. For example, in the case of symmetrical modulation or asymmetrical pulse width, the effective half-period should adopt the shortest effective on-time of the electronic switch. In procedures 1, 2 or 3, the time for applying the test voltage should be one of the following values: a) The applied voltage should rise from one-third of the specified voltage to the full voltage, and the full voltage should be maintained for (60 ± 5) s, b) (5 ~ 10) 8 (according to the specified value). Requirements: There is no sign of burning, flying, breakdown or deterioration. Ionization should not be used as a criterion for breakdown. Contents to be specified:
a) Test voltage (effective value or peak value, as applicable) b) microcable assembly (see Note 2);
center) the point on the assembly that is expected to be connected to a known potential and the value of this potential (if applicable); d) duration of application of the test voltage:
e) test frequency or pulse repetition frequency (as applicable); pulse duration (applicable to procedure 2). NOTE 21 The test voltage source may be connected to a non-nominal input assembly to obtain the required voltage. 4.4.2.3 Insulation resistance
Purpose: To measure the insulation resistance between parts of the components. Procedure: Unless otherwise specified, the insulation resistance shall be measured using one of the following specified dc voltages. 100 V ± 15 V for windings with a rated working voltage less than 500 V) 500 V ± 50 V for windings with a rated working voltage greater than or equal to 500 V The test voltage shall be applied until a stable reading is obtained. If a stable reading cannot be obtained, the test voltage shall be applied for a period of (60 ± 5) 4. If environmental conditions are required for testing, the item shall be kept under the specified conditions for at least 6 h unless otherwise specified. (See IEC 6004-1 for details.) 68 Contents of environmental tests, )
Contents that should be specified:
a) Terminals that need to be measured between each other: b) Peak working voltage of each winding;
c) Environmental condition test.
4.4.3 Power consumption
4.4.3.1 No-load current
Purpose: To verify that the core has the required quality and is correctly assembled, and at the same time verify that there are no short-circuited parts in the winding. Procedure: The specified voltage (with a frequency of one or more frequencies) should be applied from a low-impedance power supply to the input group, and all other windings should be open-circuited. The harmonic distortion of the applied voltage should be less than 6%. Use a true RMS instrument to measure the input current. The impedance of such an instrument should be low enough that the influence on the applied voltage is not more than 1%. The input voltage should be measured when its value is stable. In case of multi-phase components, all input currents should be measured.
Contents to be specified:
a) AC voltage;
b) Test frequency
c) Test group;
d) Maximum RMS value of the input current.
4.4.3.2 No-load loss
Purpose: To verify that the transformer has the required quality and is correctly assembled, and that there are no short-circuited parts in the windings. Procedure, the specified voltage (with a specified value) should be applied to the input winding through a suitable wattmeter, and all other windings should be open.
If the core flux saturation shows that other abnormal phenomena are not caused by this, the pulse duration can be specified to be greater than s0% of the specified maximum value.
**If the core flux and or other abnormal phenomena are not caused by this, a lower test frequency can be specified. ..comGB/T 8554--1998
The voltage harmonic distortion applied to the winding should be less than 6%. The power loss should be measured when its value is stable. If the wattmeter itself has obvious consumption, the measurement result should be corrected.
Contents to be specified:
a) Test voltage:
b) Test frequency;
c) Connection of winding;
d) Maximum power loss.
4.4.3.3 Quality factor Q
Purpose: To verify the quality factor of a component at a specific frequency. Procedure: The quality factor (Q) shall be measured at a specified voltage and frequency using an applicable method. For example; a) an applicable inductor bridge,
b) a circuit discharge meter (Q meter);
c) insertion loss measurement (e.g. Annex H of IEC 367-1); d) damped oscillator method (e.g. Annex G of IEC 367-1). The methods cited in c) and d) above contain the corresponding formulas and calculations. The relationship between the effective inductance and the current of the test component depends on whether the connection method (S) or parallel (P) is used. The Q values measured at frequencies below are given by: 2 yuan f1
2 yuan fL
Contents to be specified:
a) Connection of windings;
b) AC voltage,
c) Measurement frequency:
d) Limits of Q values.
Note: In the test of high-voltage components, it may be necessary to correct for capacitor losses and lead impedances. 4.4.4 Inductance
4.4.4.1. Effective inductance and effective resistance
Purpose; To measure the effective inductance of a winding; if specified, the effective resistance of the winding shall also be measured. Procedure tMeasure the inductance of a specified winding using an appropriate bridge at the specified voltage and frequency (if required, a polarizing DC current shall be applied). When specified, the effective resistance of the specified winding shall also be measured. Contents to be specified:
a) Test system;
6) Measurement method (see note);
c) AC voltage on the test winding
) Test frequency,
e) Polarization DC current.
1 For low Q value components, when the typical Q value is 10 or less, it is necessary to specify whether the test is carried out in series or in parallel. 2 There is a difference between the true ampere inductance L measured at low frequency and the effective inductance L measured when it is close to the fixed frequency. 4.4.4.2 Leakage inductance L
Purpose: To test the leakage inductance between transformer windings Procedure: The leakage inductance of the specified winding should be measured using an applicable bridge, and the remaining windings or the specified winding should be short-circuited as specified.
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