SEL-701 Motor Protection Relay

The SEL-701 Motor Protection Relay provides locked rotor, running overload, and negative sequence current unbalance protection using a patented thermal model. The thermal element accurately tracks the heating effects of load current and current unbalance while the motor is accelerating and running. You can choose from three easy settings methods:

• Motor nameplate ratings
• 45 standard thermal limit curves
• Custom curve fitting

Functional Overview

14 Speed Switch 27 Undervoltage 37 Underpower 46 Current Unbalance 47 Phase Reversal 49 Motor Thermal 50N Neutral Overcurrent 50 (P,G,Q) Overcurrent (Phase, Ground, Neg. Seq.) 55 Power Factor 59 Overvoltage 60 Loss-of-Potential 66 Starts-Per-Hour 81 (O,U) Over-/Underfrequency DFR Event Reports—Motor Starts, Motor Operating Statistics LDP Load Data Profiling SER Sequential Events Recorder VAR Reactive Power * Optional

Front- and Rear-Panel Diagrams

Front		Rear

Motor Thermal Protection

The SEL-701 Motor Protection Relay provides locked rotor, running overload, and negative-sequence current unbalance protection using a patented thermal model. Add the voltage input option for metering and voltage-based protection elements.

Nameplate, Standard, or Custom Curve Setting Methods

Set protection using motor nameplate data, choose from 45 standard curves, or create custom protection curves for advanced protection.

Advanced Reporting

Motor start reports and motor start trend data support maintenance by indicating load problems early. The load profiling function tracks motor loading and use, storing quantities every 15 minutes for up to 48 days.

Internal or External RTD Module

The SEL-701 is available with an optional internal resistance temperature detector (RTD) module that monitors up to 11 RTDs. The relay offers thermal trips and alarms, thermal model biasing, RTD open or short alarms, and temperature measurement when equipped with RTD inputs.