Date Code 20080918 Instruction Manual SEL-749M Relay
Section 1
Introduction and Specifications
Instructi on Manual
Overview
The SEL-749M Motor Relay is designed to protect three-phase motors. The
basic relay provides locked rotor, overload, unbalance, and short circuit
protection. Voltage-based and RTD-based protection are available as options.
All relay models provide monitoring functions.
This manual contains the information needed to install, set, test, operate, and
maintain any SEL-749M. It is not necessary to review the entire manual to
perform specific tasks.
Features
Standard
Protection Features
➤ Thermal Overload (thermal model) (49)
➤ Undercurrent (Load Loss) (37)
➤ Current Balance and Phase Loss (46)
➤ Overcurrent (Load Jam)
➤ Short Circuit (50P)
➤ Ground Fault (50G)
➤ Ground Fault (50N)
➤ Motor Starting/Running
➢ Protection Inhibit During Start
➢ Start Motor Timer
➢ Notching or Jogging Device (66)
➢ TCU (Thermal Capacity Utilization) Start Inhibit
➢ Anti-Backspin Timer
➢ Emergency Start
➢ Two-Speed Protection
➢ Reduced Voltage Starting (19)
➢ Stall–Speed Switch (14)
➤ Frequency (81)
Courtesy of NationalSwitchgear.com
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