The SEL-587Z High-Impedance Differential Relay is an economical and flexible relay that combines time-proven, high-impedance analog technology with the advantages of microprocessor technology. Use event reports and the Sequential Events Recorder (SER) for quick postevent analysis.
High-Impedance Bus Differential Protection—Provide high-speed, economical bus protection with a single three-phase differential bus zone. Two voltage-based setting levels are available. A high-value setting can be used for a standard trip, while a low-value setting can be used as an open-circuited CT alarm. The differential element’s internal 2000 ohm resistor allows high security to be maintained during heavy through faults or during CT saturation issues.
Simple Implementation—Apply simple settings and dedicated same-ratio CTs to create a cost-effective and easily expandable bus protection solution.
Overcurrent Protection—Provide backup overcurrent protection with the separate phase, neutral, and negative-sequence overcurrent elements, including instantaneous, definite-time, and inverse-time overcurrent elements.
Breaker Failure/Fault-Cleared Detection—Detect breaker failure and bus fault status with an overcurrent element in series with the high-impedance element.
High-Impedance Differential Protection
Provide high-speed, economical bus protection with a three-phase, high-impedance differential bus zone. High-impedance differential protection offers immunity against relay misoperation resulting from CT saturation. The SEL-587Z Relay uses internal 2000-ohm resistors to provide security against the effects of CT saturation for through faults. Internally mounted metal-oxide varistors (MOVs) are connected in parallel with the high-impedance element to clamp secondary peak voltage to less than 2 kV. Make use of simple settings and dedicated same-ratio CTs to create a cost-effective and easily expandable bus protection solution.
The SEL-587Z features separate phase, neutral, and negative-sequence overcurrent elements, including instantaneous, definite-time, and inverse time-overcurrent elements, for backup overcurrent protection.
Breaker Failure/Fault-Cleared Detection
Detect breaker failure and bus fault status by using an overcurrent element series with the high-impedance element.
Protection and Control Logic
SELogic control equations with SELogic variables and timers facilitate traditional or advanced protection schemes.
Monitoring and Reporting
Oscillographic event reports (up to ten 15-cycle reports) and metering functions eliminate or reduce external recorder and metering requirements. The SER stores the latest 512 entries in nonvolatile memory.
Serial Data Communications
Use the front and rear serial ports for communicating with ASCII terminals, a local human-machine interface (HMI), SCADA, or distributed control systems (DCSs). As an ordering option, select an EIA-232 or EIA-485 rear serial port. Through settings, select and configure the ports for SEL ASCII and interleaved SEL Fast Binary messages or for the Modbus RTU outstation protocol.