In a recent survey, the number one reason for meter change-outs in high-end applications was the need for more sophisticated communications.

Today, meters need to be flexible enough to support older communications technologies and yet be able to take advantage of newer I/P-based data networks.


Within each utility, a variety of groups use meter data:

• Billing department
• Customer service department
• Planning department
• Engineering department
• Rate department

While each department needs the data from the meter, they may each need different records, at different times, and on different schedules. Providing access for this variety of data users raises serious security questions.


Security concerns have justifiably restricted access to meters, to minimise risk. The days of a single, open dial-up phone connection to the meter are fading into history. Utilities are evaluating various encryption options to protect this sensitive metering information. Many utilities are implementing serial encrypting transceivers like the SEL-3021, as a simple, inexpensive way to satisfy network perimeter security requirements set by FERC and NERC. These transceivers provide encryption and session authentication in either a point-to-point or multi-drop configuration. The most secure approach to data collection is to use a single data server to access the meter, and then to provide internal access to the data via established network connections within the utility.


In a substation environment, meter data and power quality information may be monitored in real time, at the end of the billing period, and on demand after a significant event. As a result, high-end substation metersmust support multiple communications protocols and port configurations.

Using open, industry-standard communications protocols provides investment protection and much shorter integration times. The SEL-734 Revenue Metering System supports Modbus® RTU/TCP and DNP3 for communications with SCADA systems and load profile data collection systems. As a component of the SEL-7000 Integrated Substation System, the SEL-734 communicates with the full line of communications processors (SEL-2032, SEL-2030, and SEL-2020). Using the SEL-734 as a source for voltage and current measurements eliminates the need for expensive and high-maintenance transducers. Placing a SEL-734 Meter on each feeder gives the utility power quality engineer a tool to document sag, swell, and interruption events, and continuously monitor harmonic content. Using SELOGIC® control equations, each meter can monitor important power quality parameters and close an alarm contact when a critical threshold is met.


The SEL-734 uses a proven plug-in card/bus architecture and supports traditional communications via EIA-232 and EIA-485 ports, KYZ pulse I/O, and an internal dial-up telephone modem. Plus, the SEL-734 offers an RJ45 Ethernet port for plug-in I/P network connectivity. The advantage of using Ethernet in metering applications lies in the ability to support multiple functions over one communications interface. This one connection provides access for:

• Meter reading
• Load profile retrieval
• SCADA communications
• Power quality data collection
• Shared meter access for interchange metering
• Customer meter access

However, in substations where there are often ground potential rise issues, the SEL-734 can be connected to external communications equipment using inexpensive SEL-2800 series fibre-optic transceivers. These optical transceivers provide excellent isolation between the metering equipment and the outside world.

The flexibility of the SEL-734 design allows users to select the communications features they need now and be assured that they can upgrade to other communications technologies as they become available in the future. The design of high-end meters has a significant impact on the adaptability of the meter to easily accommodate change. The SEL-734 provides flexibility, functionality, and protection of your metering investment.