Motor Protection—The SEL-849 provides all basic motor protection features, including protection for short-circuit, load loss, load jam, frequent-starting, unbalanced current, and phase reversal conditions. Protect low- or medium-voltage three-phase induction and variable-frequency drive (VFD)-fed motors with an enhanced thermal model. Connect an external core-balanced current transformer (CBCT) to obtain sensitive ground-fault detection in high-impedance grounded systems.

Feeder Protection—Configure flexible instantaneous and time overcurrent elements (e.g., overcurrent, voltage, directional power) to protect low-voltage feeder circuits.

Second- and Fifth-Harmonic Blocking Logic—When multiple transformers are energized concurrently, it can be difficult for relays to distinguish between the magnetizing inrush current and fault current. Second- and fifth-harmonic blocking logic provides the capability to recognize inrush current and block overcurrent element operation.

Metering and Monitoring—Analyze SER reports and oscillographic event reports for rapid commissioning, testing, and post-fault diagnostics. Reduce separately mounted metering/monitoring devices by taking advantage of the SEL-849 relay’s motor start report, motor start trending, motor operating statistics, energy metering, minimum/maximum metering, and demand metering features.

Arc-Flash Mitigation—Improve worker safety using the relay’s built-in arc-flash detection (AFD). The AFD, supervised by overcurrent elements, delivers secure, reliable, and fast-acting arc-flash protection.

Direct Connection—Connect up to 690 V to the optional voltage inputs and up to 256 FLA (full-load amperes) through the built-in CT primary circuits. Use external instrument transformers for higher voltages or currents.

Optional HMIs—Install SEL-849 relays in MCC buckets, and connect the optional display modules outside the MCC for secure and safe relay access. Choose the HMI module that meets your needs: the SEL-3421 Motor Relay HMI (With LCD) or the SEL-3422 Motor Relay HMI (Without LCD).

Integration—Select from a variety of communications ports and protocols—IEC 61850 Edition 1, Modbus TCP/IP, Modbus RTU, EtherNet/IP, the IEC 62439 Parallel Redundancy Protocol (PRP), DNP3, SEL ASCII, and SNTP—to integrate SEL-849 relays into supervisory or coordinated protection and control systems.

Easier Testing, Commissioning, and Maintenance—The SEL-3421 allows you to perform key maintenance and operational tasks without plugging in a computer. The ability to view and set the IP and router address directly from the HMI screen makes relay installation easier. The HMI navigation keys can be programmed as pushbuttons to perform functions such as triggering reports or resetting values, making commissioning, maintenance, and day-to-day operation easier.