Machine Design

Solid-state overload relays

E3 and E3 Plus solid-state overload relays from Rockwell Automation, Milwaukee, have advanced protection and warning capabilities, direct-network connectivity, supplemental I/O, and can operate in failure-prevention mode. Warning functions let users proactively respond to conditions that could disrupt production. Protective capabilities include thermal overload, phase loss, stall, jam, underload, and current imbalance. E3 Plus also has thermistor-input and ground-fault protection. A builtin DeviceNet port allows users to access status information and data from the relays, as well as handle motor-control functions. The relays use Hall-effect current sensors for precise measurement of the individual-phase and ground-fault currents. IEC and NEMA configurations are available.

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