Short circuit voltage

The short-circuit voltage is a characteristic of transformers . It is the voltage that is applied to the primary winding of a transformer when the rated current flows through the primary winding when the secondary winding is short-circuited .

This characteristic can be used to test a transformer with regard to its internal resistance and its efficiency. The short-circuit voltage plays a special role in power transformers . The short-circuit voltage is specified here as a percentage of the primary rated voltage. As a rule, this value should be as small as possible so that the copper loss remains low and the voltage on the secondary side only drops slightly even with a high load. On the other hand (in the case of a secondary-side short circuit) with falling short-circuit voltage, there is an increase in the short-circuit current and the voltage drop on the primary side when the short-circuit power is low in the network that feeds the primary side.

Special cases are short-circuit-proof leakage field transformers , for example welding transformers , bell transformers and series transformers for fluorescent tubes .

Transformers connected in parallel should have the same short-circuit voltages as possible so that the power they transmit is divided according to their nominal power.

${\displaystyle u_{k}={\frac {U_{k}}{U_{n}}}\cdot 100\,\%}$

With

${\displaystyle u_{k}}$: related short-circuit voltage in%

${\displaystyle U_{k}}$: measured short-circuit voltage in V

${\displaystyle U_{n}}$: Primary nominal voltage in V

DIN EN 60076-5 - Power transformers Part 5: Short-circuit strength contains recommended values ​​for the level of the short-circuit voltage depending on the rated apparent power.

literature

• Gregor D. Häberle, Heinz O. Häberle: Transformers and electrical machines in power engineering systems. 2nd edition, Verlag - Europa - Lehrmittel, Haan-Gruiten, 1990, ISBN 3-8085-5002-3
• Wolfgang Müller: Electrical engineering specialist level, energy technology specialist computing. 1st edition, Westermann Verlag GmbH, Braunschweig, 1982, ISBN 3-14-201150-1
• Réne Flosdorff, Günther Hilgarth: Electrical energy distribution. 4th edition, Verlag BG Teubner, 1982, ISBN 3-519-36411-5
• Ernst Nourney ea (ed.): Book of tables electrical engineering. Tables, formulas, application of standards. 19th, revised. Ed., 1st Dr., Haan-Gruiten 2002, ISBN 3-8085-3029-4
• AEG, auxiliary book for electrical light and power systems, 7th edition, Verlag W. Girardet, Essen, 1956, without ISBN

Individual evidence

1. ↑ short circuit voltage. Retrieved August 28, 2017 .