Why no-load primary current is very small
as compared to full load current in transformer (as 1% of
full load current?

Answer Posted / masoom raza

when secondary is open circuit the current in primary
is low i.e only magnetizing is present to create flux
in core.but when load is connected in secondary side it
produces its own ampere turn N2I2 which reduces the flux
in core . in order to maintain the flux constant, primary current increases to balance N2I2 i.e
N1I1=N2I2(neglecting magnetizing current)
therefore primary current increases when load
is connected.

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