NO-LOAD EQUIVALENT CIRCUIT OF A TRANSFORMER
WHAT IS MEANT BY NO-LOAD TRANSFORMER?
A transformer is said to be on no-load if its secondary winding is left open circuited i.e, no load is connected to the transformer. In such conditions current in the secondary winding I₂ = 0 and hence I²R losses in the secondary will be zero.
During no-load condition, no-load current (I₀) flows in the primary side. This no-load current is about 3-5% of rated primary current and therefore the I²R losses are so small which can be neglected.
No-load current (I₀) consists of two components Iw and Iu.
Iw is the wattful/active component and it supplies for the core loss in the transformer.
Iu is the wattless/reactive component and it sets up flux in the core (in other words, it magnetizes the transformer).
NO-LOAD EQUIVALENT CIRCUIT
With the help of above information, we can easily draw the no-load equivalent circuit of the transformer. The figure below shows the no-load equivalent circuit of the transformer. Part inside the dotted box represents the ideal transformer.
|NO-LOAD EQUIVALENT CIRCUIT OF A TRANSFORMER|