The phenomenon of high transient current drawn by a transformer upon initial energization is a significant concern in power systems. This surge, often many times the normal operating current, arises from the core’s magnetic saturation as it attempts to establish its operating flux level. The magnitude and duration of this current depend on factors such as the instant of voltage application, the core’s residual flux, and the transformer’s impedance.
Understanding the characteristics of this current surge is crucial for proper equipment selection and protection. Failure to account for it can lead to nuisance tripping of protective devices, voltage dips, and potential damage to the transformer itself and connected equipment. Historically, addressing this current involved over-sizing protective devices or implementing sophisticated relaying schemes, both of which added cost and complexity.
