Transformer Protection Relay

Protect and monitor most transformer applications with the powerful SEL-487E. It offers up to five three-phase restraint inputs, three independent restricted earth fault (REF) protection elements, and two three-phase voltage inputs, all with synchrophasors. The SEL-487E limits transformer damage by responding to internal fault conditions in less than 1.5 cycles. The relay also helps avoid catastrophic transformer failure by detecting turn-to-turn faults involving as little as 2 percent of the total winding. You can minimize commissioning time and eliminate costly errors with included software that recommends matrix compensation settings. Through-fault and thermal monitoring allow you to track transformer wear and schedule maintenance as necessary. Breaker wear monitoring reduces inefficient and costly breaker maintenance, saving time and money. Optional Time-Domain Link (TiDL) technology and SEL Sampled Values (SV) technology using IEC 61850-9-2 transform the way you modernize your substation.

Applications

Multiwinding Protection—Configure the SEL-487E for transformer differential protection in transformer applications using up to five restraint currents. This includes single transformers with tertiary windings. Three independent REF elements provide protection of grounded-wye windings. You can invert individual or grouped CT or PT polarities to account for field wiring or protection zone changes.

Sensitive Turn-to-Turn Fault Detection—Avoid catastrophic transformer failure by detecting turn-to-turn faults involving as little as two percent of the total winding with the patented negative-sequence differential element.

High-Speed, Adaptive Differential Protection—Implement a two-stage slope that automatically adapts to internal or external fault conditions, even with CT saturation and heavily distorted waveforms, for fast, sensitive, dependable, and secure differential protection. The adaptive differential element responds to internal fault conditions in less than 1.5 cycles.

Diverse Transformer Applications—Protect large transformers with breaker-and-a-half high- and low-side connections. With a typical two-winding transformer application, you can use the remaining three-phase current inputs for feeder backup protection.

Generator Step-Up Protection—Protect generator step-up (GSU) transformers, and apply the built-in thermal elements (requires the SEL-2600 RTD Module) for monitoring and protecting generator and transformer winding temperatures simultaneously.

Advanced Asset Monitoring—Track transformer wear with through-fault and thermal monitoring. Advanced breaker monitoring helps reduce inefficient and costly breaker maintenance. The SEL-487E can monitor substation dc power systems for out-of-tolerance voltage levels or excessive voltage ripple.

Station Phasor Measurement Unit (PMU)—Improve power system quality with SEL synchrophasors (IEEE C37.118) from all 24 analog channels (6 voltage and 18 current sources) in your relay. You can use synchrophasors over serial or Ethernet communications to easily detect reactive loop flows, turn state estimation into state measurement, and provide an early warning of potential system instability. By receiving synchrophasor messages from two PMUs, you can implement real-time control and take action based on local and remote messages.

Dependable Backup Protection—Provide backup protection with five phase, negative-sequence, and zero-sequence overcurrent elements and ten configurable time-overcurrent elements. The SEL-487E helps you quickly identify the faulted phase with faulted-phase indications for each overcurrent element. You can set up breaker failure protection with subsidence detection to rapidly detect breaker failure and minimize system coordination times.

Digital Secondary System Technologies—Apply the TiDL-enabled SEL-487E-3/-4 with the SEL-2240 Axion TiDL nodes in the field to provide remote I/O and digitize analog signals over fiber optics. This simple and secure solution is easy to implement, with no external time source or network engineering required. Apply the SEL-487E-5 with SV technology to receive IEC 61850-9-2 SV data from a remote merging unit. TiDL and SEL SV technologies for digital secondary systems replace copper with fiber to increase safety, reduce costs associated with using copper, improve reliability, and limit the impact of an electromagnetic pulse.