The Transmission Grid 'B' consists of a transmission grid installed in a full-height EMS module. This module is used for the connection of the EMS motor/generator sets and loads as well as the protective relaying equipment for transmission grid protection. The transmission grid is opened at intervals by eight three-pole relays with normally open (NO) contacts. These relays can be operated by switches located on the module front panel or through the action of dc control relays or protective relays as part of a transmission grid protection scheme. The module has a dc bus, energized from an external dc power supply, to distribute power to the relay coils. This module and the Transmission Grid 'A', Model 3784, can be used together to create a complete multiple transmission grid when used with the Transmission Lines.