Next-generation electronic overload relay

Paul Boughton

Rockwell Automation engineers have developed the new Allen-Bradley E300 electronic overload relay. The E300 overload relay integrates communications, including EtherNet/IP, patented current-measurement technology, and time-saving I/O options, all in a modular design. The modularity provides users with the flexibility to tailor the device to meet their exact needs, thereby enabling their motor-driven processes to perform more efficiently and profitably.

Standardised EtherNet/IP communications ease installation and use – The E300 overload relay’s native dual-port EtherNet/IP option simplifies network wiring, by allowing E300 overload relays to be daisy-chained and by eliminating the need for an Ethernet switch. The E300 overload relay also provides an embedded Web server, which allows maintenance personnel to use a simple Web browser to integrate the E300 overload relay from any Internet-enabled device without the need for special software. To maintain uptime in the event of a network node interruption, the E300 overload relay supports a device-level ring (DLR) network topology.

The E300 overload relay integrates into the Rockwell Software Studio 5000 control environment from Rockwell Automation via an add-on profile. This integration brings users five mouse clicks away from communicating data between the device and a Logix controller.

The E300 overload relay contains an embedded Allen-Bradley DeviceLogix logic engine with preprogrammed motor-control logic for local and remote motor operation, simplifying device integration into an automation system. One cable connects the E300 overload relay to the operator station for local motor operation, eliminating the traditional hard-wiring time and costs, and consumption of discrete input points on the device. To ease swapping of E300 overload relays, the operator stations also support a copycat feature, which enables users to download pre-stored relay configurations at the push of a button.

Expansion I/O reduces wiring time and network node count – The E300 overload relay offers a variety of digital and analog expansion I/O modules, enabling users to maximise the relay’s capability, all within a single network node. The E300 digital expansion I/O modules provide four inputs and two relay outputs, making it ideal for complex starter scenarios where users require more inputs and outputs than provided in the base overload. Additionally, the relay’s analog expansion I/O modules allow users to select between traditional analog signals and a range of specific resistance temperature detectors (RTDs) embedded in the motor. Combining the ability to receive both traditional analog signals and RTD sensor signals in one device is an industry first.

The E300 overload relay contains a current-sensing solution, which leverages Rogowski technology. This technology enables the E300 overload relay to remain the most compact architecture-class overload relay on the market, while still offering a wide 10:1 FLA range. This wide FLA range translates to fewer SKUs,which simplifies selection and reduces inventory.

The E300 modularity – consisting of sensing, control and communication modules – provides users the flexibility to tailor the relay to meet their sensing, control and communication needs. The sensing module is available with a combination of current, voltage and ground-fault-sensing capabilities, as well as direct contactor mount, panel mount and pass-thru styles. The control module is available with variations of AC and DC digital inputs, as well as positive temperature coefficient (PTC) and ground-fault options. In addition, a variety of communication modules will enable the E300 overload relay to be used on EtherNet/IP and DeviceNet networks, and stand-alone applications.