RTUs that are used for sectionalizing have custom logic programmed in them. This capability, combined with support for 3rd party communication protocols such as DNP3, MODBUS, Motorola MDLC (Motorola Data Link Communications) protocol allows the RTU to interface to switches, which provides sectionalizing and the ability to restore power quickly.  The communications interface to the switch provides status information about the switch equipment to operations personnel at the network operations center. An RTU’s communication protocols and multiple communications ports allow them to interface to Intelligent Electronic Devices and smart sensors for monitoring and control.

 

Over the years, much of the interfacing to reclosure switches has been based on physical input/output connections between the switches and the RTUs. To enhance operations between the switches and RTUs, utilities are replacing the physical IO interface with RS232 MODBUS connections, thereby providing an improved level of operation between the central computer system and the switches in the field.

 

The typical electrical utility’s SCADA system is divided into multiple separate regions, each with its own radio system for communication purposes. RTUs in each region communicate via radio with a specific FIU (Field Interface Unit) at the central computer location. Each FIU program is customized for use in an individual region, but all are based on the GDS FIU application that has been modified to handle new communication methods created for switch data.

 

The GDS software application allows field controllers to communicate locally with switches while also communicating wirelessly over radio network with the central computer. RTUs continuously poll for data and this data is sent to the central computer where it is available to the HMI system for use in Network Operations Centers.