BS 7625:1993

Committees responsible
National foreword
Foreword
Chapter I: General requirements applicable to all
              voltage transformers
Section one - General
1 Scope
2 General requirements
3 Service conditions
4 Definitions
Section two - Rating and performance
                       requirements applicable to all
                       voltage transformers
5 Standard values of rated voltages
6 Standard values of rated output
7 Standard values of rated voltage factor
8 Limits of temperature rise
9 Insulation requirements
9a Short-circuit withstand capability
Section three - Tests - General
10 Classification of tests
Section four - Type tests
11 Temperature-rise test
12 Short-circuit withstand capability test
13 Impulse tests on primary winding
14 Wet test for outdoor type transformers
Section five - Routine tests
15 Verification of terminal markings
16 Power-frequency tests on primary windings and
     measurement of partial discharges
17 Power-frequency tests between sections and on
     secondary windings
Section six - Special tests
18 Chopped lightning-impulse test on primary windings
Section seven - Marking
19 Rating plate markings
Section eight - Terminal markings
20 General
21 Markings
Chapter II: Additional requirements for single-phase
              measuring voltage transformers
Section nine - General
22 Scope
23 Definitions
Section ten - Accuracy requirements
24 Accuracy class designation
25 Limits of voltage error and phase displacement
Section eleven - Tests for accuracy
26 Type tests
26a Routine tests
Section twelve - Marking
27 Marking of the rating plate of a measuring voltage
     transformer
Chapter III: Additional requirements for single-phase
              protective voltage transformers
Section thirteen - General
28 Scope
29 Definitions
Section fourteen - Accuracy requirements
30 Accuracy class designation
31 Limits of voltage error and phase displacement
Section fifteen - Requirements for secondary
                       windings intended to produce a
                       residual voltage
32 Rated secondary voltages
33 Rated output
34 Accuracy class
Section sixteen - Tests for accuracy
35 Type tests
36 Routine tests
Section seventeen - Marking
37 Marking of the rating plate of a protective voltage
     transformer
Chapter IV: Additional requirements for capacitor
              voltage transformers
Section eighteen - General
38 Scope
39 General requirements
40 Definitions
Section nineteen - Rating and performance
                       requirements
41 Standard reference range of frequency
42 Standard values of rated output
Section twenty - Accuracy requirements
43 Standard accuracy classes
44 Limits of voltage error and phase displacement
Section twenty-one - Effects of transients
45 Ferro-resonance
46 Transient response
Section twenty-two - Coupling device
47 Carrier-frequency coupling device
Section twenty-three - Tests
48 General
Section twenty-four - Type tests
49 Temperature-rise test
50 Impulse test
51 Ferro-resonance tests
52 Transient response test
53 Tests for accuracy
Section twenty-five - Routine tests
54 Power-frequency tests
55 Tests for accuracy
Section twenty-six - Marking
56 Marking of the rating plate of a capacitor voltage
     transformer
Figures
Appendices
A Typical and equivalent diagrams for a capacitor
     voltage transformer
B Main condition allowing tests on the equivalent
     circuit
C Burdens for the transient response tests
D Use of the equivalent circuit for the routine tests
     for accuracy
Annexes
ZA (normative) Other international publications quoted
     in this standard with the references of the
     relevant European publications
ZB (informative) B-Deviations
National annexes
NA (informative) Original IEC text amended by CENELEC
     common modifications
NB (informative) Cross-references

Gives requirements for voltage transformers. Applies to new voltage transformers for use with electrical measuring instruments and electrical protective devices at frequencies of 15 Hz to 100 Hz. The requirements can apply to auto transformers. Does not apply to transformers for use in laboratories. Coverage includes definitions, markings and type tests. Also includes diagrams and appendices.