Some standard content:
National Standard of the People's Republic of China
Synthetic test of high-voltage alternating current circuit-breakers
Synthetic testlng of high-voltage alternating current circuit-breakersGB/T 4473—1996
CB4473—84
This standard refers to the International Electrotechnical Commission standard IEC427 publication "Synthetic test of high-voltage alternating current circuit-breakers" (1989 edition) and IEC427 Amendment 1 (1992).
1 Subject content and scope of application
This standard specifies the general rules for synthetic test of alternating high voltage circuit breakers. Test technology and methods for short-circuit breaking and closing synthetic test, basic short-circuit test mode and combustion time difference This standard applies to circuit breakers within the scope of GB1984 alternating high voltage circuit breakers? The test results of short-circuit breaking and closing tests carried out in compliance with the provisions of this standard are equivalent to those of the corresponding direct tests. When other electrical appliances need to use synthetic test methods to determine the breaking and closing capabilities, they can refer to this standard for regulations. This standard involves the currently commonly used synthetic test methods and technologies, and aims to determine the criteria for synthetic tests and correct evaluation of test results. The improvement of test circuits is not restricted. 2 Reference standards
GB1984-89 AC high-voltage circuit breakers
GB/T447492 Near-field fault test of AC high-voltage circuit breakers 3 Terms
This standard adopts the definitions of GB 1984 and the following definitions: 3.1 Direct test
A short-circuit test in which the applied voltage, current, transient and power frequency recovery voltage are provided by a single power supply circuit, which may be a power system or a dedicated generator of a short-circuit test station, or a combination of the two. It can also be other forms of power supply, such as an oscillating circuit. 3.2 Synthetic test
A short-circuit test in which most or all of the current is provided by one power source (current loop) and the applied voltage and/or the recovery voltage (stability and load) are provided in whole or in part by one or more independent power sources (voltage loops). 3.3 Tested circuit breaker
The circuit breaker in the test.
3.4 Auxiliary circuit breaker
One or more circuit breakers forming part of the synthetic test circuit and used to connect the tested circuit breaker with various circuits as required.
3.5 Current circuit
The component of the synthetic test circuit, which provides most or all of the power frequency current. 3.6 Voltage circuit
Approved by the State Administration of Technical Supervision on June 17, 1996 and implemented on July 1, 1997
GB/T 4473-1996
The component of the synthetic test circuit, which provides most or all of the test voltage. 3.7 (Circuit, circuit breaker) Expected current The circuit current when a conductor with extremely small impedance replaces each pole of the tested and auxiliary circuit breakers. 3.8 Actual current
The current flowing through the tested circuit breaker (the arc voltage of the tested and auxiliary circuit breakers changes the expected current). 3.9 Variation current
It is a non-calculated current, equal to the difference between the expected current and the actual current. 3.10 Post-arc current
The current flowing through the circuit breaker gap immediately after the arc current and arc voltage have dropped to zero and the transient recovery voltage has begun to rise. 3.11 Current introduction method
is a synthetic test method in which the voltage circuit is connected to the circuit breaker under test before the power frequency current zero point. 3.12 Introduced current
The current supplied by the voltage circuit of the current introduction circuit when it is connected to the circuit breaker under test. 3.13 Voltage introduction method
is a synthetic test method in which the voltage circuit is connected to the circuit breaker under test after the power frequency current zero point. 3.14 Base system conditions
The conditions of the electrical system with parameters that can derive the rated values and test values of GB1984. 4 General
The synthetic test is an equivalent test method to the direct test. All the provisions of Articles 7.11 to 7.19 of GB1984-89 for the direct test method are applicable to the synthetic test. Considering the characteristics of the synthetic test and without affecting the equivalence of the test, some test requirements are stipulated as follows:
4.1 Test current
The voltage of the current source is low, and the distorted current generated by the arc current of the tested circuit breaker and the auxiliary circuit breaker is larger than that under the reference system conditions. This standard makes specific provisions for the amplitude and duration of the last half wave of the actual power frequency short-circuit current, see 5.1.1. For specific provisions on the introduction current of the parallel current introduction circuit, see 5.2.1. 4.2 Power frequency recovery voltage
When the voltage source is a pre-charged inductor group, it is generally difficult to meet the requirements of Article 7.13.6 of GB1984--89 due to its limited capacity. The power frequency recovery voltage lasts for at least 0.1 s. This standard allows appropriate changes, see 5.1.3. 4.3 Rated short-circuit breaking and closing test: Test mode 4 Test mode 4 includes two closing operations and three breaking operations. The synthetic short-circuit breaking and closing test is generally not able to apply the required high voltage for all operations. The specific provisions are shown in Article 7.2. 4.4 Asymmetric current breaking test: Test method 5 Asymmetric current breaking synthetic test, the change rate di/d before the breaking current passes through zero, the instantaneous value of the power frequency recovery voltage and the transient recovery voltage (TRV) are difficult to be equal to those under the reference system conditions. The specific provisions are shown in Article 7.3. 4.5 Application of the opening command of the breaking operation
In certain specific circumstances, the application of the opening command can be advanced, see Article 7.4. 4.6 Procedure for achieving three effective operations
This standard determines the arcing time difference that the circuit breaker should achieve during the test based on the distribution statistics of the arcing time that may occur when the circuit breaker with the opening synchronism that meets the requirements is in the neutral point grounded or ungrounded system and the circuit breaker breaks various short circuits, see Chapter 8. 5 Synthetic test techniques and methods for short-circuit breaking tests 5.1 General requirements for synthetic breaking test methods GB/T 4473-1996
The current and voltage loads applied to the circuit breaker during the short-circuit breaking process: Three basic stages can be distinguished, namely: the high current stage, the phase action stage and the high voltage stage (see Appendix A). In each stage, any synthetic test method must meet the following general requirements. 5.1.1 High current stage
In this stage, the load given to the circuit breaker by the test circuit should make the circuit breaker arc zone have the same state as the reference system conditions at the end of this stage, so as to prepare the same starting conditions for the subsequent root interaction stage. 5.1.1.1 Due to the low voltage of the current loop and the addition of an auxiliary circuit breaker in the current loop, the arc voltage of the tested circuit breaker and the auxiliary circuit breaker causes a relatively large distortion of the test current (see Appendix B). From the viewpoint that the energy discharged in the arc gap of the circuit breaker under test should be as close as possible to that under the reference system conditions, and taking into account the provisions of Articles 7.12.2 and 7.13.3 of GB1984-89, the following provisions can be made for the reduction of the half-wave duration of the amplitude of the test current: the amplitude of the last half-wave of the actual test current in the single-phase circuit shall not be less than the amplitude of the lower limit of the allowable value of the AC component of the breaking current specified in the test mode for test methods 1, 2 and 3; for test method 4, it shall not be less than 90% of the amplitude of the AC component of the rated short-circuit breaking current; for test method 5, taking into account the provisions of Article 7.13.4 of GB1984-89 on the percentage average value of the DC component of the current, in at least one of the tests at the end of the two half-wave arc extinctions, it shall not be less than 90% of the sum of the amplitude of the AC component of the rated short-circuit breaking current and the expected value of the DC component corresponding to the amplitude of the last half-wave. b. The duration of the last half-wave of the actual power frequency test current shall not be less than 90% of the rated power frequency half-cycle for test methods 1, 2, 3 and 4; for test method 5, at least one of the two tests with the large half-wave not extinguished shall not be less than 90% of the half-wave duration obtained after considering the influence of the specified DC component on the basis of the rated power frequency half-cycle. If the arc voltage of the circuit breaker under test has a significant effect on the short-circuit current in the system, this effect can be deducted when checking the tolerance specified above, see Appendix B. 5.1.1.2 In order to keep the test current within the specified tolerance range, the following methods may be used if necessary: increase the voltage of the current loop; appropriately reduce the inductance of the current loop so that the current at the moment of contact separation is close to the upper limit specified in this test method; b. short-circuit a part of the current and the inductance or connect a compensation branch at the beginning of the last half-wave of the current; c. increase the asymmetry of the test current or reduce its frequency. As long as the manufacturer agrees, the DC maximum value measured when the contacts are separated may exceed the specified value, and the power frequency may exceed the tolerance specified in Article 7.12.2 of GB1984-89. 5.1.2 Interaction phase
In this phase, the violent phase interaction between the circuit breaker (its arc characteristics) and the test circuit is extremely important for the breaking process. Therefore, the arc current before zero and the TRV waveform after zero in this phase should be consistent with the phase-to-phase under the reference system conditions. The specific requirements for the test circuit in this phase are shown in Section 5.2. 5.1.3 High voltage phase
In this phase, the circuit breaker is only subjected to the recovery voltage. The expected TRV acting on the circuit breaker should comply with the provisions of Articles 5.13 and 5.15 of GB 1984-89. Note: If the circuit breaker under test is connected in parallel with a low-voltage resistor, a special test procedure must be followed, see Appendix H. ② If TRV is provided by more than one circuit, the total waveform should not have obvious discontinuity. In principle, the power frequency recovery voltage should comply with the provisions of Article 7.13.6 of GB1984-89. However, when the voltage source is a pre-charged capacitor bank, the power frequency recovery voltage is a decayed DC or decayed AC voltage, or a non-decayed AC voltage with a certain proportion superimposed on it. It is generally difficult to maintain the specified value within 0.1 without decay. At this time, the following requirements should be met:. At any moment within 1/8 cycle of the rated working question after short-circuit breaking, the recovery voltage should not be lower than nuicosual
In the formula: h——first pole factor;
——rated power frequency angular frequency
U—highest voltage of the circuit breaker.
CB/T 4473-1996
b Regardless of the decayed recovery voltage, the instantaneous value of the DC voltage or the peak value of the AC voltage should be maintained at /2U/V3 as much as possible in principle, and should not be less than 0.5×Note
1 If the half cycle of the rated working amount after the short-circuit breaking is to 0.1. The circuit breaker is struck at a voltage higher than the voltage of the circuit breaker, etc., which is not considered as a failure of the circuit breaker to break. The test is allowed to be repeated, and it is considered that the performance of the circuit breaker in the zero zone has been evaluated in this test. 2 When the out-of-step breaking test is carried out, the power frequency voltage can be specified according to the same principle. 5.2 Test circuit and special requirements for breaking test 5.2.1 Parallel current method
The principle of this test method is shown in Appendix C. In principle, this test method ensures that during the interaction stage, the circuit breaker under test is in a voltage loop with the same parameters (impedance, structure, voltage) as the base system conditions. 5.2.1.1TRV regulation loop
a. The expected TRV waveform and value should meet the specified values: h. In theory, the equivalent wave impedance Zr in the interaction stage (see Figure C1) should be equal to the ratio of the specified TRV rise rate d/dt to the specified symmetrical short-circuit current zero-crossing rate d/dt %/a; du/dt
c, the sum of the stray capacitance and concentrated capacitance C in parallel with 2 produces a time delay tg = 2n - Cab
5.2.1.2 Voltage loop inductance
The inductance of the voltage loop should be between 1 and 1.5 times the inductance of the single-phase direct test circuit with specified parameters. 5.2.1.3 Introduced current
a: The expected rate of change of the introduced current when it passes through zero should be equivalent to the expected rate of change of the power frequency current when it passes through zero. b. The frequency of the introduced current should be between 250 and 1000 Hz. If the test conditions are limited, when the current introduction method is used to conduct out-of-step breaking test on a circuit breaker with a high rated voltage, it is allowed to be reduced to below 250Hz after consultation with the manufacturer. c The moment when the introduction current starts to flow through the circuit breaker under test. It should be ensured that the circuit breaker is in the voltage circuit alone (the time when it is powered by the introduction current alone is greater than the stage of significant changes in arc voltage and less than one quarter of the cycle of the introduction current. Generally, it should not be greater than 5008. When the control accuracy is limited and the requirement cannot be met, it is allowed to be no more than 700μs. Note: If the time when the circuit breaker under test is powered by the introduction current alone is less than 200ms, it should be noted that excessive load may be applied to the circuit breaker at this time.
5.2.2 Series voltage introduction method
The principle of this test method is shown in Appendix D. In the stage of high current and interaction, the circuit breaker under test is affected by the current circuit, and the recovery voltage of the current circuit is added to the circuit breaker under test through the capacitor connected in parallel with the auxiliary circuit breaker. The voltage of the voltage circuit is added to the circuit breaker under test after the phase action stage.
If this test method is used to check the circuit breaker Thermal reignition characteristics of circuit breakers, i.e. testing under outgoing fault conditions with an initial transient recovery voltage (ITRV) load or under local fault conditions, the effectiveness of the test circuit for the interaction phase needs to be confirmed. This should be agreed upon by the manufacturer, the test station and the user.
When this test method is used for tests related to the dielectric characteristics of circuit breakers, the following requirements shall be met: a. The arc voltage of the auxiliary circuit breaker shall be less than or equal to the arc voltage of the circuit breaker under test. If the arcing peaks of the two circuit breakers are approximately equal, this requirement is considered to have been met.
b. The impedance of the voltage loop shall be low enough not to affect the possible reignition or restrike. Therefore, the capacitance across the auxiliary circuit breaker is at least 10 positive F. Care should be taken to avoid excessive distortion of the current before the zero point of the working current. s. No pause should occur when the electrical circuit and the current circuit are combined. 5.2.3 Transformer circuit (SKEATS circuit) GB/T 4473—1996
The principle of this test method is shown in Appendix E. The arc voltage of the auxiliary circuit breaker and the circuit breaker under test, as well as the impedance of the current loop busbar or the leakage reactance of the current loop transformer (if used), affect the current flowing through the circuit breaker under test and the voltage applied to it after breaking. In addition, the current limiting element with human impedance in series in the voltage loop causes the current and voltage loads in the interaction stage to seriously deviate from the values under the reference system conditions. This test method is only suitable for assessing the dielectric recovery performance of the circuit breaker that has little to do with the overcoupling of the zero zone. During the test, the waveforms of the voltage and current before and after breaking should be carefully measured to ensure the validity of the test.
This test circuit can be used For synthetic closing tests, it can be used in situations where full voltage load needs to be applied multiple times, such as: the full voltage load is applied at successive current zero points in a breaking test, two breaking operations in a reclosing test, and closing and opening operations in a closing and opening test. 5.2.4 Other synthetic test methods
In order to test circuit breakers with specific characteristics or test a specific performance of a circuit breaker, other test methods may be appropriate and advantageous. Although these test methods are not included in this standard, they can still be used after agreement between the manufacturer, user and test station. There are already synthetic test methods for three-phase short-circuit breaking tests and special procedures for testing circuit breakers with low-value parallel breaking resistance. Since GB 1984 has not yet made provisions for some aspects (such as the TRV value of the last phase opened in a three-phase circuit) or there is still a lack of experience with these test methods, they are only included in the appendix for reference. 6 Synthetic test techniques and methods for short-circuit closing tests 6.1 General requirements for synthetic closing test methods Three basic stages can be distinguished from the voltage and current loads applied to the circuit breaker during the closing process of the short circuit, namely: high voltage stage, pre-ignition drive stage and keying stage (see Appendix F). Any synthetic closing test method must meet the following general requirements. 6.1.1 High voltage stage
In this stage, the circuit breaker is only subjected to the externally applied voltage. The closing voltage circuit that provides the externally applied voltage shall meet the following requirements: a. The externally applied voltage value and its tolerance shall comply with the provisions of Article 7.13.1 of GB1984-89 b. Due to the limitation of the closing voltage circuit capacity and the influence of the current limiting element or other additional elements in the circuit, an additional phase difference is generated between the externally applied voltage and the current source voltage. This phase difference should be small enough to ensure that the phase difference between the applied voltage and the short-circuit current of the current source is in principle within the power factor and its tolerance range specified in Article 7.12.1 of GB1984-89. c. If the rated short-circuit (peak) closing current test is to be performed, since the circuit is connected near the zero point of the applied voltage at this time, it is allowed to use a reduced applied voltage to test the circuit directly. 6.1.2 Pre-arcing stage
In this stage, the short-circuit current applies electromotive force to the circuit breaker, the arc burns the contacts and melts and evaporates the metal, causing the gap medium to deteriorate and heat up. Therefore, a sufficient load should be applied to the circuit breaker to check its closing capacity and the effect of closing on the subsequent breaking. a. Pre-breakdown should occur near the peak value of the applied voltage to obtain the maximum pre-arcing length or the maximum pre-arcing energy. For the convenience of testing, when the pre-breakdown voltage is greater than 87% of the specified peak value of the applied voltage, it is considered that the above requirements have been met. b. The time interval between the occurrence of pre-breakdown and the flow of short-circuit current through the circuit breaker under test should be small enough. The short-circuit current should have a percentage of DC component corresponding to the pre-breakdown phase. Note: GB1984 has not yet made provisions for the initial transient closing current (ITMC). 6.1.3 Locking stage
In this stage, it is only necessary to ensure that the closing current has the specified value and the correct waveform. 6.2 There is no fundamental difference in principle between the synthetic test circuit used for the closing test and the synthetic closing test circuits for which special requirements are known. Appendix F gives its basic composition and operating principle. The parameters of the circuit and the performance of the closing device shall meet the following requirements: The phase difference between the applied voltage and the short-circuit voltage shall be equal to 90 ± 27° after considering the action delay of the closing device, the additional phase difference between the applied voltage and the current source voltage, and the power factor of the current source. b. The current provided by the closing voltage circuit or its additional components after the pre-breakdown of the circuit breaker under test shall maintain the pre-ignition arc until the short-circuit current begins to flow.
GB/T 44731996
c. When the oscillating circuit is used to make a closing test of symmetrical short-circuit closing current on a multi-break 1I circuit breaker, measures shall be taken to ensure that the distribution of the applied voltage along each break is the same as the distribution under the alternating applied voltage. 7 Basic short-circuit test method
Due to the particularity of the closing test, the test station can select an appropriate alternative test method from Table 1 according to the conditions available. 7.1 Test methods 1, 2, and 3
only specify the breaking test. When the test station cannot perform the test according to the operation sequence of No. 1 in Table 1, the alternative method of No. 2 can be selected, in which the single breaking test 0 is used to obtain the shortest arcing time, and at the same time, each test method has 3 effective breaking operations under the specified parameters. The arcing time of the breaking operation O before the no-current time 0 should, in principle, be equal to or greater than the shortest arcing time. If the shortest arcing time is greater than 10ms, the arcing time of the 0 should be at least close to 10ms. For the convenience of testing, a closing operation under the current source voltage is allowed before any breaking operation. 7.2 Test method 4
Test method 4 should include two closing operations with specified parameters. In accordance with the provisions of Article 7.13.2 of GB1984-89 and Article 6.1.2 of this standard, these two closing operations will respectively verify the following performance of the circuit breaker; a, the ability to withstand the rated short-circuit (peak) closing current; b, the ability to close and open the rated short-circuit breaking current under the maximum pre-ignition condition. For item α, Article 7.13.2 of GB1984-89 has been stipulated, and Article 6.1.1 of this standard has also been explained. If the rated short-circuit (peak) closing current cannot be obtained in the C operation of sequence 4 to sequence 6 in Table 1, additional closing tests should be carried out at a reduced voltage until the requirements are met. For item 6, it shall be carried out in accordance with the requirements of Chapters 5 and 6 of this standard. 7.2.1 The complete rated operation sequence
See Table 1 sequence 3.
7.2.2 Alternative method 1
If the test cannot be carried out according to No. 3 in Table 1 due to the limitations of the test station conditions, Alternative method 1 of No. 4 may be used. Table 1 Combined test sequence of test methods 1, 2, 3, 4 and 5 No. Test method
Combined test method
Article 7.15 of GB 1984-89
Substitute method
Article 7.15 of GH1984--89
Substitute method 1
Substitute method 2
Substitute method 3
Breaking operation
Note: In the table, 8: 0.3s or 0.5x;
1: 180g:
For circuit breakers used for automatic reclosing
0-8-CO--- C0
On-8-Os t Os
0--CO c
Op- $-Cs0s{—Cn0s
On: 8 Cnos t--CgO.
On:--CnOs-1-COs
Cs; Closing operation with specified parameters in the combined circuit 0s: Breaking operation with specified parameters in the combined circuit; Cn: Closing operation under the external voltage of the current source and the specified making current: For circuit breakers not used for automatic reclosing alarms, |tt||0--C0——C0
0--C ::--C0
Ox—+-sO3 + --C:Os
O—t—C,Os—1—Cn0s
Os/s0g
GB/T 4473-1996
0#: Breaking operation under the breaking current specified by the current source transient and T. frequency recovery voltage rent. Among them, the role of the single breaking test and the provisions of the arcing time are before. The conditions of this alternative method are the same as the complete rated operation sequence. 7.2.3 Alternative method 2
If the C.0 test cannot be performed in the automatic reclosing test due to the limitations of the test station conditions, the alternative method 2 of No. 5 can be selected to perform the Cs0s test after the time interval. The provisions of the Op arcing time are the same as before. 7.2.4 Alternative method 3
As a transitional measure, for test laboratories that temporarily have no conditions to choose the above alternative methods, it is allowed to use the alternative method 3 of No. 6. (3 burning time is the same as before.
7.3 Test method 5
Rated asymmetric current breaking test requires three single breaking operations, see Table 1 No. 7. The rate of change when the asymmetric current passes through zero and the TRV after breaking are different from those when breaking the symmetrical current. The synthetic test cannot be automatically satisfied like the direct test. When this test is carried out by the parallel current introduction method, the positive methods of the above quantities are as follows: 7.3.1 In the arc extinguishing test at the end of the current half-wave, after the power supply voltage peak detection: The test method can be selected from the following items. a.: Reduce the voltage and charging voltage of the same circuit
Use the test circuit of test method 4, but the charging voltage is reduced as follows: UHa -Us-i VT-p+
Where: UM——Charging voltage during asymmetric test U——Charging voltage of test mode 4;
Relative value of DC component of zero-point current: The decay time constant of DC component of current is 45ms according to GB1984. The p value is obtained from the asymmetry of current Pcs when contacts are separated: Where, is the burning time.
p- pa +c-
At this time, it has the correct di/dt. When TRV is not human, the parameters of TRV are also correct. b. Further considerations when TRV's t is large
If TRV is large, for example, greater than 500us, the decrease in the power frequency recovery voltage during the t time will affect the waveform of TRV. The required expected TRV values are shown in Table 2. At this time, other correction methods need to be used or the test circuit needs to be changed. One of the methods is to still use the test circuit of test mode 4, and further reduce the charging voltage while ensuring that the TRV peak value reaches the conditions specified in Table 2. The steps are as follows: According to the current asymmetry Pcs required when the contacts are separated and the predetermined arcing time t, the asymmetry at the zero point of the head-off is calculated according to the formula listed in item a. The large half-wave The peak value Uca+ of the expected TRV during interruption is calculated by the following formula for charging voltage: UanUasUe
Wherein: cs——expected TRV peak value of test mode 4. This is the case of DC recovery voltage. If an AC recovery voltage of 50Hz is used, the charging voltage should be appropriately increased. 7.3.2 Before the peak value of any power supply voltage occurs in the test interruption at the end of the current small half-wave, the power frequency recovery voltage continues to rise to the peak value after the interruption. The test method can be selected from the following items.
Rated voltage.kv
Time coordinate, us
Test voltage and peak voltage
Asymmetry of the interruption point
Asymmetry of the interruption point
GB/T 44731996
Table 2 TRV after asymmetrical current breaking
Note: In the table, the data in the 110kV column has a reporting factor of 1.5, and the other columns have a factor of 1.3. The time constant of the direct component decay is 45m8, a: the charging voltage of the voltage circuit is reduced
The test circuit of test mode 4 is used, but the charging voltage is reduced according to the following formula UiA = Uts ·
At this time, the correct di/dl is obtained. When the t of TRV is not large, the parameters of TRV are also correct. However, the power frequency recovery voltage fails to cover the reference system conditions.
With the consent of the test station, the manufacturer and the user, the above test can be considered together with test mode 4. In the asymmetrical breaking test of the small half-wave unextinguished circuit, the di/dt: and the severity of TRV are lower than those of test mode 4. Therefore, it can be considered that the performance of the circuit breaker has been fully verified. Note: The compressed air SF has been tested in mode 4 and has not been repaired. Circuit breakers, as long as the manufacturer agrees, can use the shortest arcing time obtained in test mode 4 as the arcing time for breaking at the end of the small half wave, that is, the shortest arcing time of test mode 5. At this time, mode 5 only needs to conduct two tests of the arc that is not extinguished by the majority of the arc, and the average value of the DC component percentage is calculated from these two tests. If the test conditions need to be fully proved, the following method should be used. b.The line and charging voltage of test method 4 are used. At this time, except that the short-circuit current is asymmetrical, everything else is the same as the symmetrical breaking test. The di/dt quotient during the test is higher than the value under the reference system conditions, and the actual TRV is generally higher than the expected value in Table 2. c: The charging voltage of test method 4 increases the voltage loop inductance. The inductance L is calculated as follows:
2 yuan ft
Where: Is——voltage loop inductance in test method 4. At this time, di/d is correct, but TRV is too high.
d. Use special test circuits
These test circuits are under consideration.
e. Further considerations when TRV is large
The increase in the power frequency recovery voltage in t? time will affect the waveform of TRV. The required expected TRV value is shown in Table 2. The test method can refer to 7. 3.1 Item b.
7.4 Application of the disconnection command in the breaking test
In principle, the disconnection command should be applied only after the short circuit occurs. However, in the following cases, the disconnection command can be applied before the short-circuit current is generated, and the contact movement is allowed to occur before the short circuit occurs. At this time, the requirements of Article 7.11.3.1 and Article 7.14.2 of GB1984-89 should be met.
a, when the cumulative breaking times test is carried out under the rated short-circuit breaking current using the swing circuit as the current source: b. When an asymmetric current breaking test is carried out at a network test station where the peak current is limited. 8 Burning time difference
When the circuit breaker breaks a short-circuit fault, there is a certain minimum arcing time that can reliably extinguish the arc. In order to ensure the safe operation of the system, the system requires the circuit breaker to have a longest burning time that can reliably extinguish the arc. The difference between the two is the burning time. Time difference. The difference between the longest arcing time and the shortest arcing time of the circuit breaker successfully breaking obtained in the tests of various test modes should be equal to or greater than the required arcing time difference. Considering various random conditions and practical limiting conditions in the operation of the circuit breaker breaking the three-phase short-circuit fault of the system, calculate the distribution of the arcing time difference that may occur in the first and last opening of the circuit breaker in the neutral point grounded and ungrounded system, and take the arcing time difference that can cover 95% of the situations in operation as the basis for the provisions of this chapter.
8.1 Outgoing line fault
8.1.1 Test modes 1, 2, 3, 4
Use a single breaking operation O to calculate the shortest arcing time in of the circuit breaker in each test mode according to the first opening condition, and use it as the first effective breaking operation. In order to determine the shortest arcing time, at least two tests should be performed, one for breaking and one for restrike. The difference in arcing time between the two tests is limited to approximately 1 ms.
The arcing time of the second and third breaking operations is the value in the 3rd and 4th columns of Table 3, which are the longest arcing time required under the first opening and last opening conditions, respectively. In view of the fact that there is no provision for the TRV of the last opening phase in GB1984, and it is inconvenient to change the test circuit in the three tests of the same test method, the substitute conditions of the last opening are listed in the 5th column. This is the value after conversion and rounding. For circuit breakers used for automatic reclosing operation, the arcing time of the operation after reclosing is not specified whether it is based on the first opening or last opening condition. However, for test method 4, the arcing time of the O: operation after the reclosing should be slightly longer than the value of the first opening condition. 8.1.2 Test method 5
GB/T 4473—1996
Three single breaking operations are performed in the following order: the first breaking operation does not extinguish the arc in the small half-wave, and the shortest burning arc time tin is determined accordingly; the second and third breaking operations both extinguish the arc at the end of the large half-wave, and the parameters such as the burning arc time are shown in Table 4. 8.2 Out-of-step fault
The difference in burning time obtained in the two breaking operations shall not be less than 5.5ms10.5ms. Table 3 Arcing time difference of test methods 1, 2, 3, 4 System neutral point
Ungrounded
Arcing time + m1s
Voltage factorWww.bzxZ.net
Rate of change at current zero point
Relative value i/d
Ignition time, tms
Voltage factor
Rate of change at current zero point
Relative value i/d
First opening condition
f.+5.510.5
tm+5. 5±0. 5
Later opening condition
tumia+9,5±0. 5
tama+9.7±0. 5
Rear opening condition
tamin17.5±0.5
Note: In the table, the voltage factor is the ratio of the instantaneous value of the power frequency recovery voltage after breaking to the maximum phase voltage amplitude. The relative value of the rate of change at the zero point of the current is based on the l/dl of the zero point of the three-phase symmetrical short-circuit current. The arcing time of the actual test may exceed the upper limit specified in the 3rd, 4th, and 5th columns of the table, but shall not be lower than the lower limit! Table 4 Ignition time difference of test method 5
System neutral point
Not grounded
Arc burning time, ms
Voltage factor
Rate of change at current peak
Relative value di/dt
Arc burning time, ms
Voltage factor
Relative value di/dt
First pole-opening condition
Taut +4, 1±0. 5
t+4. 11 0. 5
Later parallel pole condition
tmin+9. d±0. 5
tal. +8, 7+0, 5
Later pole-opening alternative condition
fin +7.3=0. 5
tmh +8. 2±0. 5
Note: In the table, K is √1-5+2, see 7.3. The actual test burning time may exceed the upper limit specified in column 3.4.5 of the table, but shall not be lower than its lower limit.
A1 Three stages of the breaking process
GB/T44731996
Appendix A
Short-circuit current parallel breaking process
(reference)
Circuit breakers working in power systems have two basic positions, namely the closed position and the open position. In the closed position, the circuit breaker conducts the entire current (including the case of conducting short current), but the voltage drop across its contacts can be ignored, and the circuit breaker has only a small impedance. In the open position, the current it conducts can be ignored, but the contacts have the full voltage of the system, and the impedance of the circuit breaker is extremely low. However, the main function of the circuit breaker is to break the short circuit during the switching operation from one position to another. In this process, the impedance of the circuit breaker changes from very small to very large in a certain short time (several seconds to tens of milliseconds), and the arc is the medium connecting these two states. The voltage drop at both ends of the arc is very low when it is burning, and the conductivity is very small after it is extinguished by zero crossing, which determines that the two main loads of the circuit breaker, namely the current load and the voltage load, do not appear at the same time during the arc initiation, burning and extinguishing process of the circuit breaker contact gap. This characteristic is the basis of the synthetic test. From the current and voltage loads in the breaking test, three main stages can be identified (see Figure A1). A1.1 High current stage From the separation of the contacts to the beginning of the significant change of the arc voltage, in this stage, the short-circuit current flows through the circuit breaker, and the full end of the contact only presents a small voltage drop, namely the arc voltage. A large amount of energy is injected into the gap, which determines the free state, temperature, pressure and thermal state of the electrode of the gap.
The arc voltage produces a distorted current, which reduces the amplitude of the arc current and changes its half-wave duration. A1.2 Interaction phase
From the time when the arc voltage starts to change significantly to the time when any current (including the post-arc current) flowing through the arc is eliminated. In this phase, the state of the circuit breaker changes dramatically. As the current approaches zero, the arc voltage changes significantly, charging and discharging the parallel branch, especially the capacitive branch, affecting the shape and rate of change of the current flowing through the arc gap before the current passes zero, thus determining the conditions between the circuit breaker contacts at the current zero point.
After the current peak, the post-arc conductivity of the contact gap will produce additional damping for the transient recovery voltage, thereby affecting the voltage at both ends of the circuit breaker and the energy of the input free contact gap. This interaction between the circuit breaker and the circuit just before and after the current zero point (i.e., the phase five action phase) is extremely important for the above switching process.
41.3 High voltage stage
From the disappearance of any current flowing through the arc contact gap of the circuit breaker to the end of the test. In this stage, the contact gap of the circuit breaker is subjected to the recovery voltage.
B1 Overview
GB/T4473-1996
Time scale expansion
Figure A1 Three stages of the short-circuit current breaking process - breaking current u - rated voltage shift current drive voltage TRV - transient recovery voltage - post-drive current south: contact separation interval - the starting point of significant change in voltage; after the strong current is terminated, a large current stage appears between the groups - interaction stage, followed by a high voltage stage
Appendix B
Current rheology
(reference)
Figure B1 is a simplified diagram of the direct test circuit. According to the superposition principle, the current passing through the circuit breaker can be calculated. It consists of two parts, namely: the expected short-circuit current generated by the power supply voltage IA assuming that the circuit breaker voltage u is equal to zero, and the distorted current generated by the arc voltage assuming u0. The ia part of IA flows through the inductor L, and the ic part flows through the capacitor C connected in parallel with the circuit breaker. So we have the following formula: (ia) = 0
, so we can get
ie ia+ia
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