A substation commands such as closing and opening a disconnector or a circuit breaker can appear simple. But many interlockings and conditions have to be satisfied to…… Read more “Anti-pumping Protection”
Zero Sequence Voltage Component Uo During Single-phase Short Circuit
Single phase short circuits are most common faults in a power grid. In a solidly grounded system or a system that is grounded through a resistor and/or…… Read more “Zero Sequence Voltage Component Uo During Single-phase Short Circuit”
Motor Protection Functions
In an industrial power system, you will find many large heavy-duty AC motors. The two groups of AC motors are synchronous and asynchronous (induction) motors. Depending on…… Read more “Motor Protection Functions”
Restricted Earth Fault
On larger transformers, next to the differential protection, the restricted earth fault protection is quite common to implement. The differential current protection utilizes three phase currents from…… Read more “Restricted Earth Fault”
Synchrocheck Function
When two parts of power grid (for example, two substations connected through a long line or a power plant connecting to the rest of the grid) have…… Read more “Synchrocheck Function”
Transformer inrush current
To investigate the phenomena of a transformer inrush current, the basics of transformer analysis has to be understood together with basics of magnetism explained in this post.…… Read more “Transformer inrush current”
The B-H Curve
The B-H curve (or a magnetization curve, excitation curve, magnetic hysteresis or saturation function) is the way to describe relation between a strength of a magnetic field…… Read more “The B-H Curve”
Monostable and bistable (lockout) relays
The electromechanical relays can be roughly divided into two large groups: the monostable and the bistable relays. This time we are looking into the functionality of both…… Read more “Monostable and bistable (lockout) relays”
Circuit Breaker Failure Protection
Basic principle of a protection system of a substation the sequence of events is straightforward; if a fault is located on a line, a transformer or inside…… Read more “Circuit Breaker Failure Protection”
Park Transformation
The Park transformation or direct-quadrature-zero or dq0 transformation is essential when analyzing a three-phase system or its elements. Using the Park transformation to transform a three-phase system…… Read more “Park Transformation”
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