What does loop design achieve in electrical distribution?

Loop design in electrical distribution is primarily aimed at enhancing reliability and maintenance flexibility within the grid. By serving transformers from two directions, loop design allows for maintenance activities to be conducted without interrupting power supply to adjacent customers. This means that if one part of the loop needs to be taken offline for maintenance, power can still flow through an alternative route. This setup not only increases the resilience of the distribution system but also provides operators with greater options for rerouting electricity during maintenance or in case of outages.

In contrast to this choice, the other options do not correctly align with the benefits of loop design. Allowing only one direction of power flow limits flexibility and does not take advantage of the redundancy that loop systems offer. Preventing electricity from being distributed to customers contradicts the fundamental goal of electrical distribution systems, which is to provide reliable power to consumers. Connecting multiple substations to one main line is more indicative of a radial system layout rather than a loop configuration, which typically involves interconnections that enhance service continuity.