Lexicon DIY-Knowledge

Mains transformers


Transformadores de red

Transformateurs de puissance

Transformers are capable of converting electrical power to a specific voltage or current without mechanical motion. Their efficiency ratio lies between 90% and 98% depending on the size and type of transformer owing to the absence of moving parts.

Transformers consist of a lamellar iron core. Three different types of cross-sectional shapes are known:

Two separate windings are arranged as coils on the iron cores. They are only magnetically linked. If a current change occurs in the primary winding (N1), the magnetic field changes and a voltage is induced in the secondary winding (N2).

If the minimal losses are ignored, one can assume for an ideal transformer the following transmission ratio (Ü):

N1 U1 I2

Ü =           =           =          

N2 U2 I1

N1 = number primary windings

N2 = number of secondary windings

U1 = nominal voltage (V) primary

U2 = nominal voltage (V) secondary

I1 = nominal current (A) primary

I2 = nominal current (A) secondary

Mains transformers are used for a great variety of electrical appliances which operate on voltages which differ from the mains voltage.