SEL-587Z
High-Impedance Differential Relay
- The SEL-587Z is a flexible high-impedance differential relay that combines time-proven analog technology with the advantages of modern microprocessor technology. Designed primarily for busbar protection, it is also widely used for reactor protection and sensitive Restricted Earth Fault (REF) protection on grounded, wye-connected power transformer windings. It is an economical solution that significantly reduces panel design costs and installation space by integrating stabilizing resistors and Metal-Oxide Varistors (MOVs) inside the relay.
Key Features
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High-Speed High-Impedance Differential Protection
Provides ultra-fast tripping (less than 5 ms) for in-zone faults while maintaining high security during external faults and CT saturation. -
Integrated Hardware Solution
Includes necessary stabilizing resistors and MOVs within the relay, allowing for a complete three-phase protection system without the need for additional external components. -
Sensitive Earth Fault Protection (REF)
Optimized for precisely detecting low-magnitude ground faults in grounded, wye-connected transformer windings. -
Independent Overcurrent Elements
Features independent overcurrent elements separate from the high-impedance differential elements to complement and strengthen the protection layers. -
CT Open-Circuit Detection
Reliably detects open-circuit conditions in the CT secondary circuits using a low-set voltage differential element and generates alarms accordingly.
Convenience features
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Disturbance Analysis and Recording
Provides high-resolution event reports and Sequential Events Recorder (SER) functions for detailed analysis of the root causes of faults and the power system status. -
Real-Time Monitoring and Metering
Allows validation of CT connections using metered voltage differential quantities and monitoring of system status via real-time metering data. -
Local Control Interface
Front-panel pushbuttons can be used to control circuit breakers or perform user-defined functions without the expense of separately mounted control switches. -
Flexible Communication and Integration
Integrates with SCADA and local HMIs via an isolated rear-panel communication port supporting Modbus, SEL ASCII, and SEL Fast Messaging protocols.
The front-panel port allows for quick and easy relay configuration and event report retrieval.