A survey by Newton-Evans Research indicated that the number one reason why electricity utilities are upgrading high-end meters is to take advantage of advanced communications capabilities. Many utilities are using these advanced capabilities to improve current applications, as well as make their systems compatible with new and future communications advances.
Deployment of high-end electronic revenue meters began about 30 years ago, and since then we have seen great advances in the communications technologies used by electricity utilities. The first electronic meters of the 1970s provided ‘communications’ capabilities that simply emulated those of electromechanical meters – specifically pulse inputs/outputs, or KYZ (as they are known in the ANSI metering community). Each KYZ pulse indicated a fixed amount of energy – for example 1.8 watt-hours in secondary units. These KYZ outputs were typically connected to external pulse recording devices or to SCADA RTUs. Many of these installations exist today in systems that use electronic meters to send energy information to SCADA RTUs using KYZ pulses.
In the 1980s, dial-up telephone modems became inexpensive enough to be used in high-end electronic meters. This was one of the first remote reading technologies to be widely deployed, and dial-up modems also enabled frequent retrieval of load profile data. Instead of waiting a month to retrieve pulse recorder data, the electricity utility could now retrieve meter data as often as needed – say weekly or daily. This capability can be very important for large industrial loads. Retrieving load profile data on a frequent basis can help utilities detect metering problems much sooner, such as in the case of loss of a voltage input from a potential transformer. Similarly, a loss of communications (for example, a failed telephone line) can be detected and corrected before the monthly billing date. Dial-up communications has become one of the most common forms of high-end metering communications, especially for loads of 1 MVA and above. It remains a very important form of metering communications.
In the 1990s, more utilities started using wireless technologies to emulate circuit-switched wire-line communications. Wireless technologies enabled remote meter reading in situations that would otherwise require expensive line installations, such as crossing a car park to reach the meter. Analog cellular or GSM voice networks enabled communications with these difficult-to-reach meters.
We are now seeing increased use of computer and telecom networking technologies to fulfil all kinds of electricity utility automation functions, including metering. Many substations are being upgraded to use higher-bandwidth technologies, including fibre-optics, SONET, satellite, DSL, and Ethernet. Because Ethernet has become the standard for interfacing equipment to data networks, there has been increasing demand for high-end meters equipped with an Ethernet port.
Ethernet provides many advantages for high-end metering applications. Probably the most significant benefit is its inherent ability to support multiple functions over one communication line. With Ethernet we can use one communication connection for all of the following applications:
- Meter reading
- Load profile retrieval
- SCADA communications
- Power quality data retrieval
- Shared meter access for interchange metering
- Customer meter access.
Ethernet communication can also replace older communications paths, such as KYZ pulse wires, pulse recorders and dial-up phone lines.
In the real world, we rarely have the option of completely abandoning old technologies in favour of the new. For new high-end meters to be compatible with older systems, they have to support older communication methods. Many existing SCADA systems can only acquire metering information using KYZ pulses. New high-end meters must support these legacy systems.
Proactive utility engineers are specifying electronic meters with an Ethernet port in order to provide compatibility with future communication upgrades. KYZ pulse outputs and telephone modems provide compatibility with legacy systems.
The SEL-734 was designed with communications in mind. For compatibility with older systems, it has KYZ pulse I/O, telephone modem, EIA-485, and EIA-232 ports. For newer communications, it features built-in fibre-optics and an Ethernet port. With the SEL-734, electricity utilities can solve today’s metering communications problems while also providing a path to the future.