SEL SEL-787Z High-Impedance Differential Relay and SEL-HZM High-Impedance Module

SEL-787Z

High-Impedance Differential Relay and SEL-HZM High-Impedance Module

The SEL-787Z combines high-impedance protection principles with advanced numerical technologies to provide high-impedance differential protection.

Apply the SEL-787Z and SEL-HZM for a comprehensive single-zone bus protection solution.

Multiple resistor options in the SEL-HZM allow you to customize the device to fit your application.

An optional bypass relay and 7.8 kJ metal oxide varistors (MOVs) in the SEL-HZM protect the relay from fault currents.

The three independent high-impedance elements in the SEL-787Z can also be used to provide sensitive restricted earth fault (REF) protection on transformers with grounded-wye connections. Overcurrent elements provide backup transformer protection.

Use the 5-inch (12.7 cm) color touchscreen to configure settings, access event data, and manually reclose breakers at the relay without using a laptop.

Perform these functions remotely and simplify interconnections using a variety of common communications protocols, such as DNP3. Modbus, and IEC 61850 protocols.

High-Impedance Differential Protection—Provide high-speed, economical bus protection with a single three-phase differential zone. The highly secure high-impedance differential element in the SEL-787Z supports both per-phase voltage and current inputs.

Apply independent high-impedance elements to single-zone bus protection, reactors, generators, and large motors, or use single elements on grounded transformer windings as REF protection.

SEL High-Impedance Module (SEL-HZM)—Gain complete high-impedance bus protection with a safe and space-saving high-impedance module.

Choose from three resistor options in the SEL-HZM to provide security against CT saturation during through faults. The built-in MOV in the SEL-HZM limits voltage across the stabilizing resistor during bus faults.

Flexible Communications—Simplify interconnections using protocols like IEC 61850 Edition 2. DNP3. Modbus, EtherNet/IP, the Rapid Spanning Tree Protocol (RSTP), and more.

Use communications protocols for remote device management, including downloading event reports, upgrading firmware, and resetting the relay.

Four selectable settings groups in the SEL-787Z can cover a wide range of protection and control contingencies, increasing the adaptability of systems requiring frequent settings changes.

High-Resolution Event Records—Increase system visibility and simplify maintenance schemes with high-resolution event records containing 40 data samples per cycle at 60 Hz (48 data samples per cycle for 50 Hz applications).

Use these records to help simplify root-cause analysis.

Arc-Flash Detection (AFD)—Install and monitor up to eight point sensors or clear-jacketed fiber sensors in switchgear and other equipment with the SEL-787Z.

Optional fast hybrid outputs provide fast-acting trip outputs to the circuit breaker (less than 50 µs), significantly reducing the incident energy of an arc-flash event.

Each AFD channel continually self-tests and monitors optical circuits to detect and alarm for any malfunction, ensuring arc-flash protection for personnel and equipment.

Integrated Web Server—Use the integrated web server and a web browser to access read-only settings information, verify self-test status, inspect metering data, download event reports, and upload firmware.

Multilevel password protection separates access to read-only data reports and settings information from interfaces used to upgrade device firmware.

5-Inch (12.7 cm) Color Touchscreen Display—Access metering data, view event records, control relay operations, edit settings, and more, without a laptop.

The SEL-787Z touchscreen can be configured to display an English or Spanish language interface.

The color touchscreen clearly indicates breaker and primary equipment status, improving safety during maintenance operations.