New Technology Protects Power Transformers With the Best Rejection of Inrush Conditions and External Faults

New Technology Protects Power Transformers With the Best Rejection of Inrush Conditions and External Faults

sel-487e_w_caption.jpgNov. 13, 2008, PULLMAN, WA - Schweitzer Engineering Laboratories, Inc. (SEL) is now taking orders for two new products, the SEL-787 and SEL-487E Transformer Protection Relays. These are the first relays in the world with simultaneous harmonic blocking and restraint to eliminate tripping due to external faults and magnetizing inrush conditions. Quickly commission these relays with Commissioning Assistant, the first transformer relay software to recognize improper CT configurations and generate compensating settings.

Both relays easily 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.

"With transformer manufacturing lead-times exceeding two years and prices doubling in the past four years, no one can afford to be caught off guard losing a transformer," said SEL R&D Manager Joe Mooney. "We developed these advanced transformer relays to provide the best return on investment for every power transformer."

Compact and Versatile Two-Winding SEL-787 Transformer Protection RelayDirectly 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.

Powerful Five-Winding SEL-487E Transformer Protection Relay

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.

The SEL-787 is available now for only $2,950, the SEL-487E for $6,750. For more information on features, benefits, and applications, visit

About SEL

SEL serves the electric power industry worldwide through the design, manufacture, supply, and support of products and services for power system protection, monitoring, control, automation, and metering. SEL offers unmatched local technical support, a worldwide, 10-year product warranty, and a commitment to making electric power safer, more reliable, and more economical.


Johnnya Center, Power PR

Phone: 310-787-1940

Fax: 310-787-1970

E-mail: [email protected]

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