3 Terms, definitions and abbreviations
3.1 General definitions
3.1.308 residual voltage winding
winding of a single-phase voltage transformer intended, in a set of three single-phase transformers, for connection in broken delta for the purpose of:
a) producing a residual voltage under earth-fault conditions;
b) damping of relaxation oscillations (ferro-resonances).
5 Ratings
5.6 Rated accuracy class
5.6.301 Accuracy requirements for single-phase inductive measuring voltage transformers
5.6.301.2 Standard accuracy classes for measuring voltage transformers
The standard accuracy classes for single-phase inductive measuring voltage transformers are:
0,1 – 0,2 – 0,5 – 1,0 – 3,0
5 Ratings
5.6 Rated accuracy class
5.6.302 Additional requirements for single-phase inductive protective voltage transformers
5.6.302.2 Standard accuracy classes for protective voltage transformers
The standard accuracy classes for protective voltage transformers are 3P and 6P, and the same limits of voltage error and phase displacement will normally apply at both 5 % of rated voltage and at the voltage corresponding to the rated voltage factor.
5 Ratings
5.301 Standard values of rated voltages
5.301.1 Rated primary voltages
The standard values of rated primary voltage of three-phase transformers and of single-phase transformers for use in a single-phase system or between lines in a three-phase system shall be one of the values of rated system voltage designated as being usual values in IEC 60038.
5 Ratings
5.301 Standard values of rated voltages
5.301.1 Rated primary voltages
The standard values of rated primary voltage of a single-phase transformer connected between one line of a three-phase system and earth or between a system neutral point and earth shall be 1/times one of the values of rated system voltage.
5 Ratings
5.301 Standard values of rated voltages
5.301.2 Rated secondary voltages
The rated secondary voltage shall be chosen according to the practice at the location where the transformer is to be used.
5 Ratings
5.301 Standard values of rated voltages
5.301.2 Rated secondary voltages
For single-phase transformers intended to be used phase-to-earth in three-phase systems where the rated primary voltage is a number divided by, the rated secondary voltage shall be one of the fore-mentioned values divided by , thus retaining the value of the rated transformation ratio.
6 Design and construction
6.13 Markings
6.13.301 Terminal markings
6.13.301.3 Markings to be used
Markings shall be in accordance with Figures 301 to 310 as appropriate.