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Introduction to Motor Starting Analysis Author: Velimir Lackovic The starting current of most AC motors is several times normal full load current. Both synchronous and induction motors can draw five to ten times full load current when starting them across the line. Motor-starting torque varies directly as the square of the applied voltage. If the... Learn More

Harmonic Analysis Basics Author: Velimir Lackovic A harmonic-producing load can affect other loads if significant voltage distortion is caused. The voltage distortion caused by the harmonic-producing load is a function of both the system impedance and the amount of harmonic current injected. If the system impedance is low, the voltage distortion is usually negligible in... Learn More

Grounding System Theory and Practice Author: Velimir Lackovic The flow of current from an underground-fault condition will result in voltage gradients within and around the substation, not only between structures and nearby earth, but also along the ground surface. In a properly designed system, this gradient should not exceed the limits that can be tolerated... Learn More

Gas Insulated Substation Definitions And Basics Author: Velimir Lackovic Determining whether to use AIS or GIS technology requires assessing many elements and soliciting input data from many sections within an investor’s organization. Some elements, such as aesthetics, may significantly affect a user’s selection. It is also critical to note that the optimal substation arrangement may... Learn More

Distance Protection of Electrical Power Systems Author: Velimir Lackovic Distance protection, is a non-unit protection arrangement providing significant financial and technical benefits. Unlike phase and neutral overcurrent protection arrangements, the key benefit of distance protection is that its short circuit current coverage of the protected element is almost autonomous of source impedance changes. Since the... Learn More