Contents
How do you calculate the inrush current of a power transformer?
A 100kVA, 440V transformer has a DC winding resistance of 0.45 ohms, Calculate the inrush current of the transformer. Hence inrush current is equal to the 6 times of the full load current.
How long can a transformer inrush current exists?
This current is transient in nature and exists for few milliseconds. The inrush current may be up to 10 times higher than normal rated current of transformer. Although the magnitude of inrush current is so high but it generally does not create any permanent fault in transformer as it exists for very small time.
How much does the inrush current of a transformer last?
When transformer is energized, current many times nominal full load amperes [FLA] will flow for few cycles. Current could be anywhere from 3-14 times FLA of transformer and typically last up to 0.1s and in some special cases up to 1s. Some factors that determine magnitude and duration of inrush current are: Point of voltage waveform switching
Is there a way to limit the inrush current?
Our group through online sources, faculty, and sponsor have decided to go with a design that will try to limit inrush current by means a series resistor and controlled relay (one thoughts were to make this work for one phase a duplicate the scheme for the other 3 phases).
How does inrush current affect a circuit breaker?
This unwanted current spike can damage the device like in transformer, inrush current can cause tripping of the circuit breaker, every time it turns ON. Adjust the breaker tolerance may help us, but the components should withstand the peak value at in-rush.
How does the NTC thermistor limit the inrush current?
The NTC thermistor connects in the series with the power supply input line. It exhibits high value of resistance at ambient temperature. So, when we turn on the device the high resistance limits the inrush current to flow into the system.