24 Jul 2024


Modular overload relays can be tailored to an application

Rockwell Automation has developed an electronic overload relay that combines communications, a patented current-measurement technology, and time-saving I/O options, in a modular design. The modularity of the Allen-Bradley E300 relay is said to give users the flexibility to tailor the device to meet their precise needs.

“As adoption of electronic-overload-relay technology has risen over the past decade, so have practical expectations,” says Bill Martin, Rockwell’s global product manager. “Customers told us they value the technology’s remote monitoring and predictive trip alerts, but they also want designs that simplify programming, preserve network nodes, save wiring time, ease maintenance and minimise catalogue numbers.”

The relays contain an embedded Allen-Bradley DeviceLogix logic engine with pre-programmed motor-control logic for local and remote motor operation, simplifying integration into automation systems. A single cable connects the relay to an operator station for local motor operation, eliminating the traditional hard-wiring time and costs, and the use of discrete input points on the device. A copycat feature allows users to download pre-stored relay configurations at the push of a button, making it easy to swap the relays.

A dual-port EtherNet/IP option simplifies network wiring, allowing the relays to be daisy-chained, and eliminating the need for an Ethernet switch. An embedded Web server allows maintenance personnel to use a simple Web browser to integrate the relay from any Internet-enabled device without needing special software. To maintain uptime in the event of a network node interruption, the relay supports a device-level ring (DLR) network topology.

The patented current-measurement technology, based on Rogowski coil technology, allows the compact relays to offer a wide 10:1 FLA range, reducing parts inventories and simplifying selection and specification.

The E300 overload relay offers a choice of digital and analogue expansion I/O modules in a single network node, reducing wiring time and network node counts. The digital I/O modules provide four inputs and two relay outputs, making them ideal for complex starter applications where users need more inputs and outputs than are provided in the base overload. The analogue I/O expansion modules allow users to choose between traditional analogue signals and resistance temperature detectors (RTDs) embedded in the motor. Rockwell claims that the relay is the first that can receive both traditional analogue signals and RTD sensor signals.

The E300’s sensing, control and communication modules give users the flexibility to tailor the relay to meet their exact needs. The sensing modules are available with a combination of current, voltage and earth-fault-sensing capabilities, as well as in contactor-mounting, panel-mounting and pass-through styles. The control modules are available with various AC and DC digital inputs, as well as positive temperature coefficient (PTC) and ground-fault options. The communication modules allow the relay to be used on EtherNet/IP or DeviceNet networks, and in stand-alone applications.

The overload relay has been designed to integrate into Rockwell Software’s Studio 5000 control environment via an add-on profile. Users are five mouse clicks away from communicating data between the device and a Logix controller.

The relay will be demonstrated at the Rockwell’s Automation Fair in Houston, Texas, in November.