BS 7806:1995:2002 Edition
$167.15
Dry-type power transformers
| Published By | Publication Date | Number of Pages |
| BSI | 2002 | 44 |
Specifies cooling methods, temperature rise limits, insulation limits, test methods and degrees of protection by enclosures.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | BRITISH STANDARD |
| 2 | Committees responsible for this British Standard |
| 3 | Contents |
| 8 | Foreword Foreword to A2:1991 Foreword to A3:1992 |
| 9 | Foreword to A4:1995 Foreword to A5:2002 |
| 11 | Section 1. General 1 Scope 2 Service conditions 2.1 Normal service conditions |
| 12 | 2.2 Provision for unusual service conditions 3 Definitions 3.1 Dry-type transformer 3.1.1 encapsulated-winding dry-type transformer 3.1.2 non-encapsulated-winding dry-type transformer 3.2 Terms relating to the containment of a dry-type transformer 3.2.1 sealed dry-type transformer 3.2.2 totally enclosed dry-type transformer 3.2.3 enclosed dry-type transformer 3.2.4 non-enclosed dry-type transformer |
| 13 | 4 Tappings 5 Connections 6 Ability to withstand short�circuit |
| 15 | Section 2. Rating 7 Rating 7.1 General 7.2 Rated power Table I – Phase factors 7.3 Preferred values of rated power 7.4 Operation at higher than rated voltage 8 Rating plates |
| 17 | Section 3. Cooling methods and temperature rise 9 Identification according to cooling method 9.1Identification symbols Table II – Letter symbols 9.2 Arrangement of symbols Table III – Order of symbols 10 Temperature-rise limits 10.1 Normal temperature-rise limits |
| 18 | Table IV – Temperature-rise limits 10.2 Reduced temperature rises for transformers designed for high cooling air temperatures or special … 10.3 Reduced temperature rises for transformers designed for high altitudes |
| 19 | Section 4. Insulation levels 11 Insulation levels 11.1 General Table V – Insulation levels 11.2 Transformers for use at high altitudes |
| 21 | Section 5. Tests 12 General requirements for tests 13 Measurement of winding resistance 14 Measurement of voltage ratio and check of voltage vector relationship 15 Measurement of impedance voltage (principal tapping), short-circuit impedance and load loss 16 Measurement of no-load loss and current 17 Separate-source voltage withstand test 18 Induced overvoltage withstand test |
| 22 | 19 Lightning impulse test 20 Partial discharge measurement 20.1 General 20.2 Basic measuring circuit 20.3 Calibration of the measuring circuit Figure 1 – Basic measuring circuit for the partial discharge test for a single-phase transformer |
| 23 | Figure 2 – Basic measuring circuit for the partial discharge test for a three-phase transformer 20.4 Voltage application 20.5 Partial discharge acceptance levels |
| 24 | 21 Temperature-rise test 21.1 Methods of loading 21.2 Winding temperature-rise correction for reduced current |
| 25 | 21.3 Determination of constant temperature conditions 22 Measurement of sound level 23 Short-circuit test 24 Low temperature test 25 Thermal shock test 26 Tolerances |
| 27 | Section 6. Enclosures and safety requirements 27 Degrees of protection provided by enclosures 28 Protection against direct contact 29 Earthing terminal |
| 29 | Section 7. Miscellaneous 30 Electromagnetic compatibility (EMC) |
| 30 | Appendix A Information required with enquiry and order A.1 Rating and general data A.1.1 Normal A.1.2 Special |
| 31 | A.2 Parallel operation Appendix B Environmental, climatic and fire behaviour classes B.1 Environmental and climatic classes B.2 |
| 32 | B.3 Fire behaviour classes Annex ZA (normative) Trial use guide for special tests to prove suitability to environmental classes ZA.1 |
| 33 | ZA.2 Special tests to prove suitability to class E1 or E2 as defined by clause B1 of ZA.2.1 Class E1 transformers ZA.2.2 Class E2 transformers |
| 34 | Annex ZB (normative) Trial use guide for special tests to prove suitability to climatic classes ZB.1 ZB.2 ZB.3 ZB.3.1 |
| 35 | ZB.3.2 Annex ZC (normative) Trial use guide for special tests to prove suitability to fire behaviour classes ZC.1 General ZC.2 Checking of corrosive and harmful gas emission ZC.3 Fire test |
| 36 | ZC.3.1 Test object ZC.3.2 Validity of the test ZC.3.3 Testing installation |
| 37 | ZC.3.4 Quantities to be measured and measuring devices ZC.3.5 Calibration of the test chamber without test object ZC.3.6 Test modality |
| 38 | ZC.3.7 Test report ZC.3.8 Criteria for evaluating the test results |
| 39 | Annex ZD (informative) Installation and safety of a dry-type transformer ZD.1 Manuals ZD.2 Installation ZD.2.1 General ZD.2.2 Intrinsic safety |
| 40 | ZD.2.3 Installation precautions |
| 41 | Figure 1 – Test chamber |
| 42 | Figure 2 – Details |
