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GB 1094.5-2008: [GB/T 1094.5-2008] Power transformers -- Part 5: Ability to withstand short circuit
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Basic data | Standard ID | GB 1094.5-2008 (GB1094.5-2008) | | Description (Translated English) | [GB/T 1094.5-2008] Power transformers -- Part 5: Ability to withstand short circuit | | Sector / Industry | National Standard | | Classification of Chinese Standard | K41 | | Classification of International Standard | 29.180 | | Word Count Estimation | 29,252 | | Date of Issue | 2008-09-19 | | Date of Implementation | 2009-06-01 | | Older Standard (superseded by this standard) | GB 1094.5-2003 | | Quoted Standard | GB 1094.1-1996; GB 1094.3-2003; GB 1094.11-2007; GB/T 13499-2002 | | Adopted Standard | IEC 60076-5-2006, MOD | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 16 of 2008 (No. 129 overall) | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This Chinese standard applies to power transformer short circuit caused by an external overcurrent damage under the action should be required. This standard describes the characterization of power transformer overcurrent withstand this heat capacity calculation procedures and ability to withstand the dynamic stability of the corresponding special experimental and theoretical assessment methods (see Appendix A). This standard applies to GB 1094. 1 within the specified range of the transformer. | GB 1094.5-2008: [GB/T 1094.5-2008] Power transformers -- Part 5: Ability to withstand short circuit
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Power transformers.Part 5. Ability to withstand short circuit
ICS 29.180
K41
National Standards of People's Republic of China
Replacing GB 1094.5-2003
Power Transformer
Part 5. ability to withstand short circuit
(IEC 60076-5.2006, MOD)
Posted 2008-09-19
2009-06-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Table of Contents
Preface Ⅰ
1 Scope 1
2 Normative references 1
Ability to withstand short circuit of claim 3 1
3.1 General 1
3.2 overcurrent condition 1
Ability to withstand short circuit verification 4 3
4.1 ability to withstand short circuit Heat 4
4.2 ability to withstand short circuit dynamic stability 5
Appendix A (informative) ability to withstand short-circuit dynamic stability theory to assess 11
A. 1 Scope 11
A. 2 Overview 11
A. 11 3 Design Review Guidelines
Appendix B (Informative Appendix) IEC 60076-5.2006 system short-circuit capacity of the apparent 21
Annex C (informative) similar to the transformer 22 is determined
Foreword
Part of Chapters 3 and 4 are mandatory, the rest are recommended.
GB 1094 "Power Transformers" currently contains the following sections.
--- Part 1. General;
--- Part 2. temperature rise;
--- Part 3. Insulation levels, dielectric tests and external insulation air gap;
--- Part 4. Power transformers and reactors lightning impulse and switching impulse testing guidelines;
--- Part 5. ability to withstand short circuit;
--- Part 7. oil-immersed power transformer loading guidelines;
--- Part 10. Determination of sound levels;
--- Part 10.1. Determination of sound levels --- Application guide;
--- Part 11. Dry-type transformers.
This section GB 1094 Part 5.
The partial modification using IEC 60076-5.2006 "Power transformers Part 5. Ability to withstand short circuit" (in English).
This section according to IEC 60076-5.2006 modifying the principles adopted by redrafting.
Taking into account China's national conditions, in using IEC 60076-5.2006 when this part has made several modifications. About the technical differences have been incorporated into positive
This paper identifies and vertical single line in which they are involved with the provisions margin. This part of IEC 60076-5.2006 Main technical
Differences are as follows.
--- Cited international standards of our standards, rather than a direct reference to international standards;
--- Considering the circumstances of the transformer short-circuit impedance values in Table 1. 3.2.2.3 Added "Note 3. The different rated capacity and
Specific short-circuit impedance voltage level value, see the appropriate standard. ";
--- Taking into account the specific circumstances of the grid system, the equipment 3.2.2.4 Table 2 the highest voltage and short circuit according to China's apparent capacity
The actual situation of the grid voltage levels are listed, and the IEC 60076-5.2006, the corresponding provisions listed in Appendix B to facilitate
Control.
For ease of use, this section of IEC 60076-5.2006 made the following editorial changes.
--- Remove the IEC 60076-5.2006 Foreword;
--- Appendix A Note 1 The contents moved footnote 7);
--- With a decimal point "." Instead of a comma as the decimal point "."
This Part replaces GB 1094.5-2003 "Power transformers Part 5. Ability to withstand short circuit."
This section compared with GB 1094.5-2003 main changes are as follows.
--- Added "normative references";
--- Added "System Short nominal system voltage of 750kV apparent capacity";
--- Increase the "ability to withstand short-circuit dynamic stability theory assessment" informative appendix.
This section of the Appendix A, Appendix B and Appendix C are informative appendices.
This part is proposed by the China Electrical Equipment Industrial Association.
This part of the National Standardization Technical Committee transformers (SAC/TC44) centralized.
This section is drafted. Shenyang Transformer Research Institute, TBEA Shenyang Transformer Group Co., Ltd., Xi'an Electric transformer limited liability
Any company, Baoding Tianwei Electric Co., Ltd., Shanghai Electric Power Company, TBEA Hengyang Transformer Co., Ltd., Beijing Huatai change
Pressure Co., Ltd, and Power Electric Group Co., Ltd., Guangzhou Prosperous Electric Co., Ltd., Shandong Dachi Electric Co., Ltd.
The main drafters of this section. Guo Yan, Zhang Zhong country, Tao Dan, Zhong Juntao Wang Long, Zhang joy, Jiang Yimin, Chen Dongfeng, Wang hl
Xuzi Hong, Fan Jianping, Xu Changhua.
This part of the standard replaces the previous editions are.
--- GB 1094.5-1971, GB 1094.5-1979, GB 1094.5-1985, GB 1094.5-2003.
Power Transformer
Part 5. ability to withstand short circuit
1 Scope
GB 1094 This section provides power transformers in the overcurrent effect caused by an external short circuit should be no damage to the requirements. This section
It describes the characterization of power transformers withstand such heat resistance over current calculation program and bear the corresponding test special ability and dynamic stability
Theoretical Assessment Method (see Appendix A).
This section applies to GB 1094.1 Suo transformer within the scope of the provisions.
2 Normative references
The following documents contain provisions which, through reference in this Part of GB 1094 constitute provisions of this section. For dated references,
All subsequent amendments (not including errata content) or revisions do not apply to this section, however, encourage the agreement on this section
Whether the parties can study the latest versions of these documents. For undated reference documents, the latest versions apply to this section.
GB 1094.1-1996 Power transformers - Part 1. General (eqv IEC 60076-1.1993)
GB 1094.3-2003 Power transformers Part 3. Insulation levels, dielectric tests and external insulation air gap (IEC 60076-3.
2000, MOD)
GB 1094.11-2007 Power transformers Part 11. Dry-type transformers (IEC 60076-11.2004, MOD)
GB/T 13499-2002 Application guide for power transformers (idt IEC 60076-8.1997)
Claim 3 Ability to withstand short circuit
3.1 General
Transformer and its components and accessories shall be designed and manufactured to withstand external short circuit under the conditions specified in this section 3.2 and the thermal efficiency of dynamic stability
It should be no damage.
External short circuit includes a three-phase short circuit, phase short circuit, two phase to ground and ground fault. These fault currents induced in the windings in Part
Points referred to as "over-current."
3.2 overcurrent conditions
3.2.1 General Conditions
3.2.1.1 require special consideration of conditions
Following cases overcurrent size, duration or frequency of occurrence of an impact, the need for special consideration and should be in the transformer technical specification
Give clearly defined.
--- Regulating transformer impedance small, we need to consider the impedance of the current limiting device is connected;
--- Generator transformers are vulnerable because the generator is connected with the loss of synchronization system produced higher overcurrent;
--- Direct rotary motor (such as a motor or a synchronous phase modulation device) connected to the transformer under system fault conditions, the state of power generation was run
The rotary transformer supplying current to the motor;
--- Special transformers and transformer installed in a high failure rate of the system (see 3.2.6);
--- Failure, higher than the rated operating voltage fault occurs on a non-terminal.
3.2.1.2 Current limit on boosting transformer
When combined impedance transformer and booster systems lead to short-circuit current value is so great that the design withstand this excess current transformer is difficult or without
When the economic, manufacturing and users should consult together to determine the maximum allowable over current value. In this case, the user should take measures to limit the overcurrent to producing
The determined and the flag over the maximum current value on the nameplate.
3.2.2 having two separate windings
3.2.2.1 This section provides a three-phase or three-phase transformer rated capacity of the group is divided into three categories.
Ⅰ class. 25kVA ~ 2500kVA;
Ⅱ class. 2501kVA ~ 100000kVA;
Ⅲ class. 100000kVA above.
3.2.2.2 Unless otherwise specified, symmetrical short-circuit current (rms value, see 4.1.2) shall be measured transformer short-circuit impedance coupled system
Short-circuit impedance calculation.
For class Ⅰ transformer, if the system short-circuit impedance is equal to or less than 5% of the transformer short-circuit impedance, the short-circuit current calculation system
Short-circuit impedance should be negligible.
Peak short-circuit current 4.2.3 should be calculated.
3.2.2.3 Table 1 shows the minimum value of the transformer short-circuit impedance at rated current (primary tap) under, if you need a lower short-circuit impedance value
When the transformer to withstand short circuit capacity by producing and user consultation.
Table 1 has a minimum of two independent short-circuit impedance of the transformer windings
Rated capacity/kVA Minimum short-circuit impedance /%
25 to 630
631 to 1250
1251 to 2500
2501 ~ 6300
6301 to 25,000
25001 to 40000
40001 ~ 63000
63001 to 100000
Than 100,000
4.0
5.0
6.0
7.0
8.0
10.0
11.0
12.5
> 12.5
Note 1. The rated capacity is greater than the short-circuit impedance value is generally determined by the manufacturer 100000kVA and users negotiation.
Note 2. In the case of the single-phase transformers three-phase group, the value of the rated capacity for three-phase group.
Note 3. The different rated capacity and voltage levels of specific short-circuit impedance values, see the appropriate standard.
3.2.2.4 In order to obtain a symmetrical short-circuit current design and testing required by the user to provide the Department of the installed location of the transformer at the time of inquiry
Short-circuit the system apparent capacity.
If no apparent short-circuit the system capacity, in accordance with Table 2 selection.
Table 2 System Short apparent capacity
Nominal System Voltage/kV highest voltage for equipment Um/kV apparent short circuit capacity/MVA
6,10,20
7.2,12,24
40.5
72.5
18,000
60,000
Note 1. If not specified, the system is considered zero sequence impedance positive sequence impedance ratio is 1 to 3.
Note 2. If the user requires otherwise, the system short-circuit apparent capacity can also be specified in Appendix B of the selection, but it should be specified in the contract.
3.2.2.5 transformer having two separate windings, usually only consider a three-phase short circuit, which can be considered virtually fully satisfy other possible
(Except for special circumstances contemplated in Note 3.2.5), including the type of fault.
NOTE. When the windings Zigzag Connection, a single earth fault currents may be larger than the three-phase short circuit current. However, the two involved in the stem, higher electrical
Current value is limited to half of the windings. Further, the current in the other star-connected windings are less than the current three-phase short circuit. As for the three-phase
Single-phase short circuit or a short circuit on the dynamic stability of the windings produces more damage, and structural design of the windings related. Manufacturing and users should consider what kind of short
Road type agreement.
3.2.3 multi-winding transformers and autotransformers
Winding (including stable and auxiliary windings) overcurrent shall be determined according to the impedance transformer and systems. The operation should be considered
It can produce different types of system failures, such as. the transformer and grounding systems and related ground fault and phase fault (see
GB/T 13499-2002). Characteristics of each system (at least in the short-circuit depending on the capacity and zero sequence impedance positive sequence impedance ratio in the range) should
Presented by the user at the time of inquiry.
Triangle three-phase transformer coupling stabilizing winding should be able to withstand the operation may arise, and related systems and ground conditions relating
Different types of system failures arising from overcurrent.
In the case of the single-phase transformers three-phase group unless the user will confirm the special protection measures to prevent phase short circuit, the stable
Winding should be able to withstand short-circuit its terminals.
NOTE. The auxiliary winding designed to withstand short-circuiting its terminals may not be economical. At this time, it should take appropriate measures (such as the use of series reactors, or
In some cases the use of fuses) to limit the over-current value. In addition, it should pay attention to prevent the line section between the transformer and its Short-protection device
Circuit fault.
3.2.4 booster transformer
Booster transformer impedance value may be small, so the winding overcurrent mainly by the characteristics of the system at the installation location of the transformer to determine
set. These features should be user inquiry and ordering made.
If the booster transformer is connected directly to a transformer for the voltage amplitude and/or phase shift adjustment, this should be able to withstand up transformer
Both devices synthesizing the impedance produced by an overcurrent.
3.2.5 directly connected with other electrical transformer
When the transformer is directly connected with other electrical appliances, the electrical impedance will limit the short circuit current. Press Association between the manufacturer and users
Yee, you can transformers, transformer directly connected to the system and with the respective electrical impedance counted in the total.
If the connection between the generator and the transformer is good, even in this context the possibility of two-phase or phase to ground fault can be ignored
Not time, the above also applies to the generator transformer.
NOTE. If the connection status between the generator and the transformer as described above, then for neutral grounding of the star - delta-connected generator transformers, with
Star connection winding is connected to system ground fault occurs, or in the case of the generator is not synchronized with the system, it is the most serious short-circuit may occur
Happening.
3.2.6 special transformers and transformer installed in the high failure rate of the system
For special occasions (such as electric transformers and transformer to the traction power supply systems) or operating conditions (such as the failure of the connected system
More often), transformer withstand frequent over-current capability, and users should manufacture specialized consultation. About the system of abnormal operating conditions
The case member, the user should be provided in advance to the manufacturing side.
3.2.7 tap changer
When the transformer is equipped with tap-tap-winding should be able to withstand the same short-circuit overcurrent. But it does not require on-load tap-changer
Having the ability to switch the short-circuit current.
3.2.8 neutral point terminal
Star-connected or zigzag coupling winding neutral terminal shall be the maximum possible flow through this terminal over current designs.
4 Ability to withstand short circuit verification
Requirements of this chapter applies to both prescribed GB 1094.1 oil-immersed power transformers, also apply to dry under the GB 1094.11
Power transformers.
4.1 heat resistance to withstand short circuit
4.1.1 Overview
Transformer short-circuit withstand heat capacity should be verified by means of calculation. Calculation according to the provisions of 4.1.2 - 4.1.5.
4.1.2 Symmetrical short-circuit current I
For two independent three-phase transformer winding, symmetrical short-circuit current rms value I shall be calculated as follows.
I = U
Sang 3 × (Zt + Zs)
(1)
Where.
I --- symmetrical short-circuit current rms value, in kA (kA);
Zs --- system short-circuit impedance, ohms per phase (Ω) (equivalent star connection), calculated as follows.
Zs = U
(2)
Where.
Us --- nominal system voltage, in kilovolts (kV);
S --- System Short apparent capacity, units of MVA (MVA).
U and Zt according to the following provisions.
a) For the main tap.
U --- considered rated voltage Ur winding unit is kilovolt (kV);
Zt --- converted to the windings considered short-circuit impedance 1), each phase ohms (Ω) (equivalent star connection), calculated as follows.
Zt = z t × U
100Sr
(3)
1) where the symbol Zt t and z are used instead of GB 1094.1-1996 Z and z, which is consistent with the purpose of this section 4.2.3, in order to avoid confusion.
2) tap voltage is defined in GB 1094.1-1996 5.2.
Where.
Z t --- at the reference temperature, rated current and rated frequency measured by the main tap short-circuit impedance, expressed in%;
Sr --- transformer rated capacity, in units of MVA (MVA).
b) In addition to the other outside the main tap tap.
U --- considered in the corresponding tapped winding voltage (unless otherwise specified) 2) units of kilovolts (kV);
Zt --- converted to the corresponding tap winding consider short-circuit impedance per phase ohms (Ω) represents.
For multi-winding transformers, autotransformers, booster transformers and transformer directly connected to other appliances, which were calculated overcurrent
Press 3.2.3,3.2.4 3.2.5 or conduct.
All transformers, except the 3.2.2.2 circumstances, should consider the system short-circuit impedance.
NOTE. Zigzag Connection of winding, single-phase ground fault circuit current may be significantly greater than the three-phase short circuit fault current. Therefore, in the calculation of Zigzag Connection
Winding temperature rise should consider increasing the current value.
4.1.3 Symmetrical short-circuit current duration
Unless otherwise specified, the duration of the heat is used to calculate the short-circuit withstand capability of the current I is 2s.
Note. For auto-transformer and short circuit current exceeds 25 times the rated current of the transformer, after consultation with users of manufacturing, short-circuit current duration may be small
To 2s.
4.1.4 The maximum permissible value of each winding mean temperature
After each winding, respectively, for applying a predetermined duration of the symmetrical short-circuit current I by 4.1.2 and 4.1.3, which at any tap position
The average temperature θ1 should not exceed the maximum specified in Table 3.
Winding temperature equation (4) and Equation (5) used in the θ0 should be expressed as maximum allowable ambient temperature and at rated conditions resistor
The winding temperature measurement and. If the measured winding temperature rise is not applicable, winding starting temperature θ0 should be the maximum permissible ambient temperature
Winding insulation system allows temperature sum.
Table 3 each winding after short circuit at an average temperature of the maximum allowable value
Type transformers
Insulation system temperature /
(Thermal insulation levels in brackets)
The maximum temperature /
Aluminum winding copper windings
Oil-immersed 105 (A) 250 200
Dry
105 (A)
120 (E)
130 (B)
155 (F)
180 (H)
Note 1. When the winding is made of high-tensile aluminum alloy wire, by producing and user negotiated a higher maximum temperature, not exceeding an amount
The temperature should be copper windings.
Note 2. When the oil-immersed transformer insulation system used is not A-level, user by producing and negotiated different maximum allowable temperature.
4.1.5 Calculation of temperature θ1
The average temperature of the winding after short circuit θ1 by the following formula.
θ1 = θ0 + 2 ×
(Θ0 + 235)
(Copper windings) (4)
θ1 = θ0 + 2 ×
(Θ0 + 225)
(Aluminum windings) (5)
Where.
θ0 --- winding starting temperature, in degrees Celsius (℃);
J --- short circuit current density in Ann per square millimeter (A/mm2), symmetrical short-circuit current rms value is calculated;
Note. Equation (4) and Equation (5) is derived by adiabatic conditions, and the short-circuit duration 10s only valid when not exceeded. Formula coefficients in Table 4
The parameters listed in drawn.
Table 4 material parameters
parameter
material
Copper and aluminum
100 ℃, specific heat/(J/kg · ℃)
100 ℃ when the density/(kg/m3)
100 ℃ when the resistivity/(μΩ · m)
398.4
0.0224
0.0355
4.2 ability to withstand short circuit dynamic stability
4.2.1 Overview
If the user has requested, the ability to withstand short circuit dynamic stability by either of the following to verify.
---Experimental Verification;
--- Calculation, design and manufacture of synchronization verification.
The method used to verify the choice, users and manufacturers should be determined in consultation before ordering.
Short circuit test for a particular test (see 3.11.3 of GB 1094.1-1996) shall be specified in the contract. 4.2.2 The test shall be ~
Requirements 4.2.7 will be.
Large-capacity transformer may not be tested in accordance with this section, such as. restricted experimental conditions. In this case, the test conditions by the user and the system
Made party consultation.
When selecting a synchronization verification by calculation, design and manufacturing requirements for the short-circuit test has been done in a similar transformer or a representative model
Short-circuit tests on to prove it. Identification of criteria similar transformers Appendix C.
4.2.2 transformer short-circuit condition before the test
4.2.2.1 Unless otherwise specified, the test shall be performed on new transformers ready for operation. When the short-circuit tests, protection accessories, such as air
Body relay and pressure relief device should be installed on the transformer.
Note. no effect on the performance of the short-circuit accessory (such as a removable cooler) may not be installed.
4.2.2.2 before short-circuit test transformer should be GB 1094.1-1996 of routine tests, but at this stage, it is not required to do
Lightning impulse test.
If the winding with a tap, should short-circuit test where the tap position on the measure reactance, and the resistance measurement is necessary.
Reinspection of all reactance measurements should be within ± 0.2%.
The test report includes the results of routine tests, including, in the beginning of the test should be ready before the short circuit.
4.2.2.3 When the short-circuit test began, the average temperature of the winding should preferably be between 10 ℃ ~ 40 ℃ (see the GB 1094.1-1996
10.1).
During the short-circuit tests, since the flow through the short-circuit current, winding temperature may rise. When the test line should be considered furnished class I transformer
This situation.
The test shall be carried out when the current test phase is the maximum asymmetry value.
The first peak asymmetrical test current (kA), calculated as follows.
In the formula, symmetrical short-circuit current I is determined according to 4.1.2.
K To calculate the initial test current offset coefficient, and Sang 2 considers the sine wave peak other than the root-mean values.
Sang coefficient k × 2 (also known as crest factor) related to the X/R, where.
Reactance and System X --- transformer reactance and (Xt + Xs), expressed in Ω;
R --- transformer resistance and the resistance of the system and (Rt + Rs), in Ω, where Rt is the resistance at the reference temperature (see
GB 1094.1-1996 10.1).
If the short-circuit current calculations include the system short-circuit impedance, except as otherwise specified, the system should be assumed Xs/Rs value is equal to the transformer
The Xt/Rt values. Table 53) lists the different peak X/R values because values for practical applications.
3) Table 5 according to the following formula derived from crest factor.
Sang k × 2 = [1+ (e- ( + π/2) R/X) sin] Sang × 2
Where.
e --- the natural logarithm of;
--- phase angle equal arctgX/R, radians.
Table 5 coefficient value k 2 × Sang
X/R 1 1.5 2 3 4 5 6 8 10 14
K Sang × 2 1.51 1.64 1.76 1.95 2.09 2.19 2.27 2.38 2.46 2.55
Note. If X/R is another value between 1 to 14, then k Sang × 2 Available obtained by linear interpolation.
X0 t --- electrical resistance component z t,%;
Z t transformer short-circuit impedance% --- reference temperature.
If not otherwise specified, when X/R > 14, the coefficient k Sang × 2 is assumed to be.
For class Ⅱ Transformer. Sang 1.8 × 2 = 2.55;
Ⅲ class of the transformer. Sang 1.9 × 2 = 2.69.
4.2.4 short-circuit ...
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