Test guide for power transformers
1 Scope
This standard specifies procedures and methods of routine tests, type tests and special tests for oil-immersed type and dry-type power transformers.
This standard applies to the tests of oil-immersed type and dry-type power transformers.
This standard may apply to special transformers.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding any corrigendum), or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the latest editions of the standards indicated below. For undated references, the latest edition of the document referred to applies.
GB/T 311.6-1983 High voltage test techniques—Part 5: Sphere-gaps for voltage measurement (eqv IEC 60052:1960)
GB/T 507-2002 Insulating liquids—Determination of the breakdown voltage at power frequency (eqv IEC 60156:1995)
GB 1094.1-1996 Power transformers—Part 1: General (eqv IEC 60076-1:1993)
GB 1094.2-1996 Power transformers—Part 2: Temperature rise (eqv IEC 60076-2:1993)
GB 1094.3-2003 Power transformers—Part 3:Insulation levels, dielectric tests and external clearances in air (eqv IEC 60076-3:2000)
GB/T 1094.4-2005 Power transformers—Part 4:Guide to the lightning impulse and switching impulse testing—Power transformers and reactors (IEC 60076-4:2002, MOD)
GB 1094.5 Power transformers—Part 5: Ability to withstand short circuit (GB 1094.5-2003, IEC 69076-5:2000, MOD)
GB/T 1094.10 Power transformers—Part 10: Determination of sound levels (GB/T 1094.10-2003, IEC 60076-10:2001, MOD)
GB/T 5654-1985 Measurement of relative permittivity, dielectric dissipation factor at power frequency and volume resistivity of insulating liquids
GB 6450 Dry-type power transformers (GB 6450-1986, eqv IEC 60726:1982)
GB/T 6451-19 Specification and technical requirements for three-phase oil-immersed power transformers
GB 7597-1987 Method of sampling for transformer and turbine oils in electric power industry
GB/T 7600-1987 Determination of water content in transformer oils in service by coulometric method
GB/T 7601-1987 Determination of water content in transformer oils in service by gas chromatographic method
GB/T 10228-1997 Specification and technical requirements for dry-type power transformers
GB/T 16274-1996 Specification and technical requirements for oil immersed power transformers 500kV
GB/T 16927.1-1997 High voltage test techniques—Part 1: General test requirements (eqv IEC 60060-1:1989)
GB/T 17623-1998 Determination of componental contents of gases dissolved in insulating oil by gas chromatography method
DL/T 423-1991 Determination of air content in insulating oil by vacuum differential pressure method
3 Main symbols
Ur—rated voltage, V;
Ir—rated current, A;
Sr—rated power, kVA;
K—voltage ratio;
R—resistance, Ω;
T—temperature, ℃;
Rxg—phase resistance, Ω;
Rxn—line resistance, Ω;
Kδ—air density correction factor;
Kd—air density;
fr—rated frequency, Hz;
P0—no-load loss, W ;
I0—no-load current, %;
Pk—load loss corrected to reference temperature, W;
Zk—short-circuit impedance corrected to reference temperature, %;
Zi—short-circuit impedance, Ω;
Pr—resistance loss, W;
θp—average temperature, ℃;
Δθ—temperature rise, K;
Z0—zero sequence impedance, Ω/phase;
Zs—system impedance, Ω.
4 Test procedure
This test procedure is not standardized. The items with the test type not indicated are routine tests.
To be specific, the following items are included.
a) Strength test of oil tank (type test);
b) Oil tank leak test;
c) Measurement of dielectric characteristics:
1) Determinations of insulation resistance, absorption ratio and polarization index (for transformers of 35kV, 4,000kVA and above, 66kV and above, the insulation resistance and absorption ratio shall be given; for those of 330kV and above, the insulation resistance value, absorption ratio and polarization index shall be given; for other small and medium-sized transformers, only the insulation resistance value is given);
2) Measurement of dielectric dissipation factor (for those of 35kV, 8,000kVA and above, and 66kV and above).
d) Transformer oil test:
Contents
Foreword i
1 Scope
2 Normative references
3 Main symbols
4 Test procedure
5 Oil tank leak test (routine test)
5.1 General requirements
5.2 Test purpose
5.3 Test method
5.4 Judgment of test results
6 Measurement of dielectric characteristics (routine test)
6.1 Test purpose and items
6.2 Measurement of insulation resistance, absorption ratio and polarization index
6.3 Measurement of dielectric dissipation factor
7 Transformer oil test (routine test)
7.1 Measurement of breakdown voltage
7.2 Measurement of dielectric dissipation factor
7.3 Determination of moisture content
7.4 Determination of air content
7.5 Gas chromatographic analysis of dissolved gas
8 Voltage ratio measurement (routine test)
9 Calibration of voltage vector relation (routine test)
9.1 Voltage ratio bridge method
9.2 Double voltmeter method
9.3 Tester method
10 Winding resistance measurement (routine test)
11 Insulation tests (routine, type and special tests)
11.1 General
11.2 Switching impulse and lightning impulse tests
11.3 Applied voltage withstand test (routine test)
11.4 Short-duration induced over voltage withstand test (ACSD)
11.5 Long-duration induced AC voltage withstand test (ACLD)
11.6 Induced over voltage withstand test of dry-type transformer
12 Partial discharge measurement (routine test)
13 Measurement of no-load loss and current (routine test)
14 Measurement of short-circuit impedance and load loss (routine test)
15 On-load tap-changer test (routine test)
15.1 Operation test
15.2 Auxiliary circuits insulation test
16 Temperature rise test (type test)
17 Mechanical strength test of oil tank (type test)
17.1 Test purpose
17.2 Test methods
17.3 Judgment of results
17.4 Precautions
18 Determination of sound levels (special test)
19 Measurement of zero-sequence impedance of three-phase transformer (special test)
19.1 General
19.2 Measurement of zero-sequence impedance with balanced ampere turns
19.3 Measurement of zero-sequence impedance without balanced ampere turn
20 Test on ability to withstand short circuit (special test)
21 Measurement of no-load current harmonic (special test)
22 Measurement of power absorbed by fan and oil pump motor (special test)
22.1 Preparation before test
22.2 Test methods
22.3 Precautions
