SEL-710-5/SEL-710 Motor Protection Relay
Protect asynchronous (induction) and synchronous motors with one SEL-710-5 Motor Protection Relay. New features include broken rotor bar detection and variable-frequency drive (VFD) support as well as options for arc-flash detection, differential protection, and synchronous motor protection. The synchronous option also includes, at no additional cost, a voltage divider accessory to interface with the motor excitation system.
Front- and Rear-Panel Diagrams
The SEL-710-5 Motor Protection Relay is a full-featured, multifunctional relay that provides complete ac induction and synchronous motor protection and control, including automatic starting. The SEL-710-5 can be implemented for a wide variety of applications, such as fans, blowers, compressors, air handlers, pumps, conveyors, chippers, crushers, screeners, feeders, augers, and bucket elevators.
Standard Motor Protection
Standard features include SEL’s trusted current-, voltage-, and thermal-based motor protection with current differential. The powerful thermal model dynamically calculates motor slip to provide precise temperature tracking with less time required between restarts and more time during the start sequence.
Synchronous Motor Protection and Starting
The SEL-710-5 provides two levels of field over- and undervoltage, field over- and undercurrent, and field resistance protection as an option. It provides automatic synchronization by applying the dc field voltage to the motor field at the correct slip frequency and rotor angle to lock the motor to synchronous speed. It also includes out-of-step and loss-of-field protection.
Overcurrent-supervised arc-flash protection provides secure arc-flash tripping by operating when both arc-flash and overcurrent conditions occur. This important feature improves worker safety in areas where high fault current and high incident energy arc-flash events are possible.
Broken Rotor Bar Detection
The broken rotor bar feature detects and reports signature sideband frequencies—current signature analysis (CSA)—that occur in the presence of broken rotor bars. Early detection reduces maintenance costs and helps prevent associated thermal and mechanical damage contributing to catastrophic motor failure.
Advanced protocols, such as IEC 61850, DNP3, Modbus TCP/IP, Modbus RTU, Telnet, FTP, SNTP, and ASCII, support communication with legacy and modern supervisory and control systems.
Reliable Rugged Hardware
The SEL-710-5 operates in extreme conditions, with an operating temperature range of –40° to +85°C (–40° to +185°F), and is designed and tested to exceed applicable stan-dards, including vibration, electromagnetic compatibility, and adverse environmental conditions.