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BS 171:1970

Withdrawn
Withdrawn

A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.

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withdrawn

A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.

Specification for power transformers
Available format(s)

Hardcopy , PDF

Withdrawn date

05-08-2008

Language(s)

English

Published date

31-03-1970

Co-operating organizations
Foreword
Specification
Section one. Scope and service conditions
1 Scope
2 Service conditions
3 Provision for unusual service conditions
Section two. Definitions
4 Definitions
Section three. Rating
5 General
6 Rated power
7 Preferred values of rated power
Section four. Tappings
8 General
9 Off-circuit tappings
10 Principal tapping
11 Categories of voltage variation
12 Specification of voltage conditions
13 Tapping range
14 Tapping quantities
Section five. Identification according to cooling method
15 Identification symbols
16 Arrangement of symbols
Section six. Limits of temperature rise
17 Temperature rise limits
18 Reduced temperature rises for transformers designed
    for high cooling medium temperatures
19 Reduced temperature rises for transformers designed
    for high altitudes
Section seven. Insulation levels
20 General
21 Windings with graded insulation
22 Transformers for use at high altitudes
Section eight. Ability to withstand short circuit
23 General
24 Overcurrent conditions
25 Mechanical requirements
26 Thermal requirements
27 Transformers directly associated with other
    apparatus
28 Special transformers
29 Short-circuit tests
30 Auxiliary windings
Section nine. Rating plates
31 Rating plates
Section ten. Vector diagrams, connections and terminals
32 Connections of phase-windings
33 Phase displacement between sets of windings;
    marking and position of terminals
Section eleven. Tolerances
34 Tolerances
Section twelve. Tests
35 General requirements for type, routine and special
    tests
36 Measurement of winding resistance (routine test)
37 Voltage ratio measurement and check of polarity or
    vector-group symbol (routine test)
38 Measurement of impedance voltages (routine test)
39 Measurement of load loss (routine test)
40 Measurement of no-load loss and current (routine
    test)
41 Test of temperature rise (type test)
42 Application of dielectric tests
43 Induced overvoltage withstand test (routine test)
44 Separate source voltage-withstand test (routine
    test)
45 Full wave impulse-voltage withstand test including
    chopped waves (special test)
46 Impulse-voltage withstand test including chopped
    waves (special test)
47 Subsequent dielectric tests
48 Measurement of zero phase-sequence impedance
    (special test)
Section thirteen. Insulating liquids
49 Oil
50 Synthetic insulating liquid
Section fourteen. Fittings
51 Provision of fittings
Appendices
A Information required with enquiry and order
B Selection of insulation levels
C Calculation of voltage drop (or rise) for a
    specified load condition
D Transformer connections, winding designations,
    terminal markings and vector diagrams
E Parallel operation of 3-phase transformers
F Examples of specifications for transformers with
    voltage variation facilities
G Typical connection diagrams for induced voltage
    tests on windings with graded insulation
H Fittings
J Supplementary information concerning high-voltage
    tests
K Impulse-voltage testing of low-voltage windings
Tables
1 Phase factors
2 Preferred values of rated power for 3-phase
    transformers
3 Letter symbols
4 Order of symbols
5 Temperature rise limits for dry-type transformers
6 Temperature rise limits for oil-immersed type
    transformers
7 Insulation levels for windings and connected parts
    not designed for impulse-voltage tests
8 Insulation levels for windings and connected parts
    designed for impulse-voltage tests
9 Categories of graded insulation
10 Insulation levels for the neutral ends of windings
    of transformers having graded insulation
11 Overcurrent limits for transformers with two
    windings
12 Maximum permissible average winding temperatures
    (T2)
13 Values of factor a
14 Tolerances
15 Reference temperatures
16 Correction factors
17 Fittings for oil-immersed type transformers
18 Additional fittings for oil-immersed type
    transformers
19 High-voltage tests at reduced levels
Figures
1 The use of vector-group symbols
2 Method for determining final temperature rise of
       oil
2A Method for determining temperature of winding at
       shut-down
3 Designation of connections of 3-phase
       transformers by vector-group symbols
3A Example of three single-phase transformers
       connected to form a 3-phase bank
3B-3J Examples of designating letters for windings and
       terminals
3K Marking and relative position of terminals for
       two-winding transformers
3L-3P Vector diagrams for 3-phase transformers
3Q Vector diagrams for single, 2 and 3/2-phase
       transformers
3R-3T Terminal marking plates
4-5A Parallel operation of transformers
6-13 Typical connection diagrams for induced voltage
       tests on windings with graded insulation
14 Recommended position of fittings

Performance and test requirements for 1 kV A single-phase and 2 kV A polyphase: no upper limits to rated power or voltage. May also be applied as appropriate to special transformers not at present covered by separate British Standards.

Committee
PEL/14
DevelopmentNote
Supersedes 68/4425 DC. (06/2005)
DocumentType
Standard
Pages
86
PublisherName
British Standards Institution
Status
Withdrawn
SupersededBy

Standards Relationship
IEC 60076:1967 Similar to

BS 7354:1990 Code of practice for design of high-voltage open-terminal stations
BS 787-4:1972 Specification for mining type flameproof gate-end boxes Gate-end boxes for drilling machines (for use on 3-phase a.c. circuits up to 650 V)
BS 3535-1:1990 Isolating transformers and safety isolating transformers General requirements
EN 60146-1-3:1993 Semiconductor convertors - General requirements and line commutated convertors - Part 1-3: Transformers and reactors
BS EN 60146-1-3:1993 Semiconductor convertors. General requirements and line commutated convertors Transformers and reactors
BS 7361-1:1991 Cathodic protection Code of practice for land and marine applications
BS 2538:1954 Specification for air-cooled flameproof single-phase lighting transformer units supplied from high voltage systems
BS 4417:1969 Specification for semiconductor rectifier equipments
BS 7375:1996 Code of practice for distribution of electricity on construction and building sites
BS 3399:1961 Specification for transformers for use in ships
BS 4996:1973 Specification for line traps for power line carrier systems
BS 2G 127:1967 Specification for power and current transformers for use in aircraft electrical power supply systems
BS 5550-7.5.2:1981 Cinematography. Production and presentation. Film and television location lighting Specification for location lighting power distribution units
BS 6436:1984 Specification for ground mounted distribution transformers for cable box or unit substation connection
BS 5611:1978 Application guide for on-load tap-changers
DEFSTAN 02-535/2(2003) : 2003 REQUIREMENTS FOR TRANSFORMERS FOR POWER SERVICES
BS 787-3:1971 Specification for mining type flameproof gate-end boxes Gate-end boxes with lighting transformers
BS 5067:1985 Specification for flameproof transformers for use in mines
BS 6435:1984 Specification for unfilled enclosures for the dry termination of HV cables for transformers and reactors
BS 2562:1979 Specification for cable boxes for transformers and reactors

BS 205(1943) : LATEST GLOSSARY OF TERMS USED IN ELECTRICAL ENGINEERING
BS CP1009(1959) : LATEST MAINTENANCE OF INSULATING OIL (WITH SPECIAL REFERENCE TO TRANSFORMERS AND SWITCHGEAR)
BS 2757(1956) : LATEST DETERMINING THE THERMAL CLASSIFICATION OF ELECTRICAL INSULATION
BS 2045:1965 Preferred numbers
BS 2562:1979 Specification for cable boxes for transformers and reactors
BS 148:1959 Specification for insulating oil for transformers and switchgear
BS 923:1972 Guide on high-voltage testing techniques.
BS 2914:1972 Specification for surge diverters for alternating current power circuits

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