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Complications of Magnetizing Inrush (contd..) |
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Thus, it is clear that peak flux during energization is twice as high as the steady state peak sinusoidal value. Depending upon the residual flux, it can be even higher. Now,  , where  is the knee point flux density of core. Thus, during energization, the core is driven deep into saturation. The resulting H and hence magnetizing current can be very high (up to 20 times full load current). This current is known as inrush current of transformer. So far, we have assumed  . But in general,  depends upon the remnant flux in the core and H can be anywhere between  and  . Hence,  during energization will vary from  to  . Fig 39.8 visualizes the nature of the inrush current. |
