Technical Documents

This section brings together technical documents and calculation spreadsheets developed to support studies, projects, specifications, analyses and practical applications in electrical engineering, power systems, hydroelectric power plants, substations and industrial facilities.

The materials cover topics such as power generation, transformers, auxiliary systems, electrical protection, short-circuit currents, nominal voltages, voltage drops, equipment sizing and other subjects related to the design, operation and analysis of electrical systems.

Whenever applicable, Excel calculation spreadsheets are provided to assist engineers, students and technical professionals in performing studies, evaluations and engineering calculations.

Technical document presenting criteria for defining nominal voltages in low-voltage systems, voltage variation analysis, motor operation, control transformers and auxiliary AC systems in hydroelectric power plants. Includes practical examples for evaluating operating conditions and mitigating undervoltage and overvoltage situations. 

Technical document presenting criteria for defining nominal voltages of electrical systems and equipment, analyzing voltage variations, voltage drops, motor operation, transformers, relays and contactors. The material provides guidance for evaluating existing installations and developing new low-voltage electrical system projects. 

Technical document for calculating three-phase short-circuit currents using the MVA Method developed by Moon H. Yuen. The methodology simplifies short-circuit calculations in power systems, allowing results to be obtained through only a few calculation steps without memorizing numerous formulas. The material includes the technical document and the IEEE reference publication. 

Technical document presenting criteria for load assessment, power consumption calculations and sizing of auxiliary service transformers and emergency diesel generator sets. The material covers normal, maintenance and emergency operating conditions, including alternator and diesel engine selection for hydroelectric power plants, SHPPs and substations. 

Technical document and calculation spreadsheet for determining terminal voltage in power transformers, considering transformer electrical characteristics, percentage impedance, tap positions, apparent power, power factor and loading conditions. The material supports voltage regulation studies, operational analysis, substations and power system applications. 

Technical document presenting criteria for diesel generator set specification, alternator transient reactance calculations and terminal voltage analysis during load application and motor starting conditions. The material includes a technical document and calculation spreadsheets. 

Technical document presenting practical criteria for preliminary feeder sizing, including current-carrying capacity, resistance and reactance values, thermal short-circuit criteria, minimum protected cable lengths and maximum protection operating times. Includes a technical PDF document and an Excel calculation spreadsheet. 

Technical document presenting methodologies to determine the voltage available at the load and the voltage required at the source considering feeders, constant-power loads, variable-power loads and motor starting conditions. The material includes a technical document and two Excel calculation spreadsheets. 

This content presents the calculation of generation voltage in hydroelectric power plants, allowing the determination of generation voltage values of the generating units based on the electrical conditions of the generation system and the high‑voltage substation.

The method considers, in an integrated manner, the high‑voltage substation data, the electrical characteristics of the step‑up transformers, and the power supplied by the generating units of the powerhouse, being applicable to steady‑state studies, operational limit verification, and analysis of voltage behavior in the electric power system.

Technical document presenting criteria for configuration, protection, selectivity, ground fault location and component sizing of direct current systems. The material analyzes overvoltage issues, batteries, chargers and DC panels applicable to hydroelectric power plants, SHPPs, substations and industrial facilities. 

This section brings together technical documents developed to support engineers, students and professionals in the electrical and electromechanical fields in the analysis, design and evaluation of electrical systems.

The contents cover theoretical concepts, design criteria, practical application examples and calculation methodologies related to power transformers, auxiliary systems, emergency diesel generator sets, short-circuit currents, feeders, DC systems and hydroelectric power plant installations.

Whenever applicable, calculation spreadsheets are provided to support engineering studies and allow users to reproduce the examples presented in the documents.

The technical guides and practical applications were prepared for educational and technical purposes, aiming to provide useful information for engineering projects, technical analyses, feasibility studies, operation and maintenance activities.

This technical document presents concepts, criteria, and applications related to the rehabilitation of hydroelectric power plants, including equipment modernization, increased operational reliability, extended lifespan, replacement of obsolete components, performance improvements, and technological adaptation of facilities. The material addresses technical aspects used in revitalization and modernization studies of existing hydroelectric projects.

Technical document presenting the fundamentals of load-frequency control in power systems, from systems with isolated generating units to interconnected systems. It addresses primary and secondary regulation, Tie-Line Bias Control, Area Control Error, economic dispatch and its interaction with speed governors. It also includes criteria for adjusting generating-unit speed governors, considering permanent and transient droop, time constants, inertia, overspeed, and transfer functions.

Document prepared by Eng. Sergio Carvalhaes Moreira.