Many motors are required in a thermal generating plant and range in size from fractional horsepower to several thousand horsepower. These motors may be supplied with the equipment they drive or they may be specified by the electrical engineer and purchased separately. The small motors are usually supplied by the equipment supplier and the large motors specified by the electrical engineer. How this will be handled must be resolved very early in the project. The horsepower cut-off point for each voltage level must be decided. The maximum plant voltage level must be established. A voltage of 13.8 kV may be required if very large horsepower motors are to be used. This must be established very early in the plant design so that a preliminary one-line diagram may be developed.
Breaker Schemes in Substations — Types, Design, Advantages, Disadvantages, and Comparison Author: Engr. Aneel Kumar Figure 1: Infographic overview of breaker schemes commonly used in substations. Introduction The breaker scheme or busbar arrangement in a substation defines how incoming feeders, outgoing feeders, and power transformers are connected to the bus. The choice of scheme has a direct impact on system reliability, maintainability, safety, and cost . A simple bus scheme is economical but vulnerable to outages, while advanced schemes such as breaker-and-a-half or double-bus/double-breaker provide very high reliability but at much higher cost and design complexity. Engineers select breaker schemes considering fault tolerance, maintenance needs, space requirements, expansion possibilities, protection coordination, and capital investment . Below, we explain eac...