Connectivity

The electrical grid consists of power plants that generate electrical power, electric power transmission that carry it over long distances, electric power distribution that carry it to customers and finally of electrical substations that step voltage up or down to enable transmission and distribution. These components form an interconnected network for electricity delivery from power producers to consumers. This document describes connectivity; the way CIM models how these components are connected.

CIM uses connectivity nodes (cim:ConnectivityNode for AC and cim:DCNode for DC) to model connectivity of equipment. However, connected pieces of (conducting) equipment are not directly associated to such a connectivity node. In stead they are associated via terminals (cim:Terminal for AC and cim:DCTerminal for DC):

A different, more visual representation might look like this:

By definition connectivity nodes are points where terminals of conducting equipment are connected together with zero impedance. This enables terminals to be used as points of connectivity-related measurement in the network such as voltages or phase information (ABC). So, in practice, if you have two terminals associated to a breaker and your measurement at these terminals show different voltages then you know this breaker is open. This is a benefit of modeling connectivity using connectivity nodes via terminals.

Any terminal is associated to exactly one piece of conducting equipment and it is associated to at mot one connectivity node. On the other hand, any connectivity node can have any number of terminals. Just as any piece of conducting equipment.