Transformer on No-Load

 When the primary of a transformer is connected to the source of an ac supply and the secondary is open circuited as shown below, the transformer is said to be on no load. The Transformer on no load alternating applied voltage will cause flow of an alternating current I₀ in the primary winding, which will create alternating flux Ф. No-load current I₀, also known as excitation or exciting current, has two components the magnetizing component Im and the energy component I_e as shown in phasor diagram .I_m is used to create the flux in the core and Ie is used to overcome the hysteresis and e ddy current losses occurring in the core in addition to small amount of copper losses occurring in the primary only (no copper loss occurs in the secondary, because it carries no current, being open circuited.)