The SEL-787 and SEL-487E Transformer Protection Relays are the first relays in the world with simultaneous harmonic blocking and restraint to eliminate tripping due to external faults and magnetizing inrush conditions.

Users can quickly commission these relays with Commissioning Assistant, the first transformer relay software to recognize improper CT configurations and generate compensating settings.

Both relays integrate with substation control systems via multiple serial ports, dual failover Ethernet connections, and multiple protocols. For communications-assisted protection schemes, both relays include high-speed SEL MIRRORED BITS® communications.

Directly replace most electromechanical transformer relays with the compact SEL-787 to protect two-winding transformers in industrial plants, utilities, and other mission-critical sites. The relay connects to networks with Modbus®, DeviceNet(tm), DNP3, and IEC 61850 protocols. It also accepts plug-in modules for ac voltage and neutral current, I/O, communications, or RTD inputs.

Protects and monitors transformers with two to five windings. It detects turn-to-turn faults as small as 2 percent of the total winding. The subcycle adaptive differential element minimizes damage from internal faults. Monitor and control breakers and disconnect switches through large front-panel LCD one-line diagrams.

Schweitzer Engineering Laboratories, Inc.
www.selinc.com.