Major Features and Benefits: –

The SEL-787 Transformer Protection Relay provides unsurpassed protection, integration, and control features in a

flexible, compact, and cost-effective package.

Standard Protection Features. Two-winding dual-slope differential protection with harmonic blocking and

restraint, and phase, negative-sequence, residual-ground, and neutral-ground overcurrent elements provide backup protection. Breaker failure protection is included for two three-pole breakers.

Optional Protection Features. Use the SEL-787 with optional voltage inputs to provide volts/hertz protection with frequency tracking from 20 to 70 Hz for generator step-up and other variable frequency applications. Implement load shedding and other control schemes with over- and underfrequency and over- and undervoltage elements. In addition, use Sensitive Restricted Earth Fault (REF) protection for grounded-wye transformers.

Transformer Monitoring. Use transformer through-fault monitoring to measure accumulated through-fault levels of the transformer. Monitor ambient, load tap-changer (LTC), tank, and transformer oil temperature through the use of optional 4–20 mA or RTD thermal inputs.

Operator Controls. Four programmable front-panel pushbuttons each with two programmable LEDs allow for a

wide variety of uses including easy trip and close control and status indications for a breaker. Implement local and

remote operator control schemes through use of 32 local and 32 remote control bits.


Relay and Logic Settings Software. ACSELERATOR QuickSet® SEL-5030 Software reduces engineering costs for

relay settings and logic programming. Tools in QuickSet make it easy to develop SELOGIC® control equations. Use

the built-in phasor display to verify proper CT polarity and phasing.

Metering and Reporting. Built-in metering functions eliminate separately mounted metering devices. Analyze

Sequential Events Recorder (SER) reports and oscillographic event reports for rapid commissioning, testing, and

post-fault diagnostics. Unsolicited SER protocol allows station-wide collection of binary SER messages.

Additional Standard Features. Includes Modbus RTU, Event Messenger support, MIRRORED BITS® communications, load profile, support for 12 external RTDs (SEL-2600 series module), IRIG-B input, advanced SELOGIC, configurable labels, IEEE C37.118-compliant synchrophasor protocol, and SEL-2812 compatible ST connectors fiber-optic serial port.

Optional Features. Select from a wide offering of optional features, including IEC 61850, Modbus TCP/IP, Simple Network Time Protocol (SNTP), DNP3 LAN/WAN, DNP3 Serial, 10 internal RTDs, expanded digital/analog I/O, voltage inputs, additional EIA-232 or EIA-485 communications ports, and single or dual copper wire or fiber-optic Ethernet ports.

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