Modern power system design is the application of sound engineering practices to electrical systems primary develoted to the generation, distribution, and consumption of electrical power.  Ideally, this process is  governed by minimum code requirements, standards from agencies such as IEEE and ANSI, and commonly accepted industry standards.  Occasionally, the process is marred by little appreciation for tribal knowledge, incomplete understanding of standards, or the rote execution of a design with little appreciation for the application.     As engineer, we strive to avoid these pitfalls by furthering our understanding though the acquisition of additional source materials.  Unfortunately, despite the ubiquity of the internet, groups such as IEEE and ANSI don't provide their standards for free, and the availability of regionally enforced code is an area of ambiguity.  Fortunately, some manufacturers have provided resources that are invaluable to engineers:

General Electric provides The Art and Science of Protective Relaying free for download.  A quick perusal of the Bibliography for each chapter reveals the history of this document, and despite the dates, this document remains as relevant as ever.  The principals are still applied in modern protective relays, and numerous Defense Plant Corporation era facilities still employ electromechanical protection to great success.

As a modern supplement to GE's definitive guide, Schweitzer Engineering Laboratories provides numerous resources under their Literature section.  In addition to the Journal of Reliable Power, they provide white papers and technical papers outlining the methodologies used in a modern digital relay and their appropriate application.  Be warned, they do require a free account for access to their library.

Eaton publishes a Consulting Application Guide, a rather fancy name for the Eaton/Cutler-Hammer catalog of all relevant industrial equipment.  Despite the commercial nature, the first chapter provides substantial reference material on all manner of subjects.  From protection, to system layout and generation, the Eaton catalog touches on many relevant subjects.

Image provided by the Seattle Municipal Archives