BS EN 50482-2008 pdf download.INstrument transformers Three-phase inductive voltage transformers having Um up to 52 kV.
Unless otherwise specified below the temperature rise of a voltage transformer at the specified voltage, at the rated frequency and at the rated burden or at the highest burden, if there are several rated burden, at any power factor between 0.8 lagging and unity, shall not exceed the appropriate value given in Table 3 of EN 60044-2:1999.
a) All three-phase transformers, irrespective of voltage factor (VF) and time rating, shall be capable of operating continuously with a balanced three-phase voltage of 1,2 times rated primary voltage. The steady state temperature rise shall not exceed the limits given in Table 3 of EN 60044-2:1999.
b) Three-phase earthed transformers having a voltage factor of 1,5 for 30 s or 1,9 for 30 s shall after the application of 12 times rated pnmary voltages for sufficient time to reach stable thermal conditions, be capable of operating with a balanced three-phase voltage of respectIvely 0,866 or 1,1 times the rated primary voltage applied for 30 s, one line terminal of the primary winding being connected to the neutral of that winding. The temperature rise shall not exceed by more than 10 K the value specified in Table 3 of EN 60044-2:1999.
C) Three-phase earthed transformers having a voltage factor of 1,9 for 8 h shall after the application of 1,2 times rated primary voltage for sufficient time to reach stable thermal conditions, be capable of operating with a balanced three-phase voltage of 1,1 times rated line-to-line voltage applied for 8 h, one line terminal of the primary winding being connected to the neutral point of the winding. The temperature rise shall not exceed by more than 10 K the value specified in Table 3 of
EN 60044-2:1999.
Table 3 of EN 60044-21999 as well as the text and the notes, except a). b), and c) above apply.
6 Design requirements
6.1 Insulation requirements
These requirements apply to all types of inductive voltage transformers. For gas-insulated voltage transformers supplementary requirements may be necessary (presently under consideration in
IEC/TC 38).
8 Type tests
8.1 Temperature-rIse tests
Subclause 8.1 of EN 60044-2:1999 apphes.
8.2 Short-circuit withstand capability test
Subclause 8.2 of EN 60044-2:1999 apphes.
8.3 Impulse test on primary winding
8.3.1 General
The impulse tests shall be performed in accordance with HD 588.1 Si.
The impulse voltage tests generally consist of voltage applications at reference and rated voltage levels.
The reference impulse voltage shall be between 50 % and 75 % of the rated impu’se withstand voltage.
The peak value and waved-shape of the impulse voltage shall be recorded.
Evidence of failure in the test may be given by variation in the records at both reference and rated impulse withstands voltages.
8.3.2 Lightning impulse test
The test voltage shall have the appropriate value given in Table 4 of EN 60044-2:1999 depending on the highest voltage for equipment and the specified insulation level.
8.3.2.1 Earthed primary windings
The test voltage shall be applied between each line terminal of the primary winding and earth. The neutral point of the primary winding, the non-tested line terminals, the frame, case (if any) and the core (if intended to be earthed) shall be earthed during the test.
The test shall be performed with both positive and negative polarities. Fifteen consecutive impulses of each polarity, not corrected for atmospheric conditions, shall be applied to each of the three terminals.
8.3.2.2 Unearthed primary winding
The test voltage shall be applied between each line terminal of the primary winding and earth; the other line terminals, the frame; case (if any) and the core (if intended to be earthed) shall be earthed during the
The test shall be performed with both positive and negative polarities. Fifteen consecutive impulses of each polarity, not corrected for atmospheric conditions, shall be applied to each of the three terminals.BS EN 50482-2008 pdf download.