Why Utilities Must Migrate from TDM to IP

Utilities that have made huge investments in time-division multiplexing (TDM) infrastructures that use circuit switching to communicate with protective relaying and supervisory control and data acquisition (SCADA) systems are now making the switch to IP-based systems. .

Over decades, utilities have made huge investments in time-division multiplexing (TDM) infrastructures that use circuit switching to communicate with protective relaying and supervisory control and data acquisition (SCADA) systems that protect substations and the power grid. In fact, investment in TDM by utilities rivals that of the telecommunications industry as a whole, where in 2017 72% of companies still had TDM infrastructure, according to research firm Nemertes.

Preserving their investments in TDM makes good business sense for utilities. These solutions are reliable and secure, managing the utilities’ most mission-critical applications.

However, Internet Protocol (IP), packet-based networks, which carry two-way data efficiently, are the networks of choice for advanced metering infrastructure systems and distributed energy resources. Effectively, IP is the future of utility communications and utilities are looking for ways to migrate TDM communications to IP.


Facing a TDM dilemma

Why must utilities move from TDM to IP, when reliable TDM networks work well for mission critical substation communications? Simply put, power utilities face TDM obsolescence because telecommunications companies are no longer using it.

Telecommunications companies, the largest users of TDM equipment, adopted packet-based technology long ago. Furthermore, FCC rules adopted in 2016 have pushed this transition even more quickly.

This means that utilities must either quickly transition to IP, a costly option, or find solutions that allow them to bridge the gap.


Current options are unwieldy

Not many of today’s solutions meet all requirements for IP migration, which leads power utilities to deploy an overlay of solutions. This results in a piecemeal approach that renders the transition from TDM to IP both complex and expensive.

“When a utility installs an IP-based transport for its substation communications backbone, it must find a way for TDM applications to communicate on the network. Typically, the utility employs a so-called two-box solution to accomplish this task, “ said Manny Duvelson, product manager.

A two-box solution includes two devices. One is a gateway for each TDM device that converts the legacy TDM interface to IP packets. The second is a device that transports the packets between substations.

Furthermore, IP networks are more complex to deploy in the field than TDM technology because they employ software not used as part of TDM implementations. The combination of hardware and software challenges make it difficult for utilities to implement cost-effective solutions that can make the most of mission critical TDM investments.


A customer-based approach

The Aclara Radio Frequency Laboratories (RFL) business line, part of Hubbell Power Systems,  decided to tackle the issue with a Voice of Customers program, spending six months answering the following question: “if we were to design the perfect solution to meet requirements and solve substation communications IP migration challenges, what would it look like?”

The results was the RFL eXmux® 4500 Multi-Service Access & Transport Platform, designed to meet customer requirements for IP migration and address major gaps in other market solutions. The product offering:

  1. Modernizes substation communications without degrading the performance of older, trusted equipment.
  2. Offers software to help engineers of all experience levels work seamlessly during network migration.
  3. Delivers a single integrated network solution offering IP migration for all legacy TDM integration protocols.
  4. Ensures that the most stringent application such as Current Differential Relay would retain or even exceed existing performance.
  5. Supports security that goes beyond NERC CIP requirements and incorporates industry best practices to ensure data availability, integrity, and confidentiality.


Award-winning solution

The eXmux 4500 platform allows power utilities to migrate to IP by upgrading substation communication infrastructures without having to replace legacy applications or compromise reliability.

It features a drag-and-drop user interface that offers a guided approach to provisioning and helps engineers of all experience levels connect TDM to an IP network in a few hours. The system is future proof, allowing an orderly switchover from TDM to IP. TDM payload cards in the equipment can be replaced with Ethernet boards in the same slot.

Recently the eXmux® 4500 won an IMPACT Award from the Utilities Technology Council at its UTC Telecom & Technology 2019 conference, which was held this year in Ft. Worth, Texas. IMPACT Awards honor UTC Associate Member Organizations impacting the industry through innovative and proven hardware, software, or service solutions.

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