Project Description

Transformer Protection Products

The high importance and cost of transformers make it crucial to maintain these assets. SEL has developed a wide variety of advanced transformer protection relays for all your transformer applications, providing top-of-the-line protection and control. Choose the relay that best suits your transformer needs.

Related Products

SEL-487E Transformer Protection Relay

Protect and monitor most transformer applications with the powerful SEL-487E Transformer Protection Relay. Apply up to 5 three-phase restraint inputs, three independent restricted earth fault protection elements, and 2 three-phase voltage inputs, all with synchrophasors. Limit transformer damage by responding to internal fault conditions in less than 1.5 cycles.

SEL-387/SEL-387A Current Differential and Overcurrent Relay

The SEL-387 Current Differential and Overcurrent Relay provides protection, control, and metering for transformers, machines, buses, breakers, and feeders. Features include four three-phase current inputs with independent restrained and unrestrained differential protection, programmable single- or dual slope differential characteristic, circuit breaker monitor, battery voltage monitor, and enhanced SELOGIC® Control Equations.

SEL-387E Current Differential and Voltage Relay

The SEL-387E Current Differential and Voltage Relay provides protection to two- or three-winding power transformers. Voltage inputs for power metering, overexcitation protection, and over-/underfrequency load shedding provide versatile solutions for power apparatus protection.

SEL-587 Current Differential Relay

The SEL-587 Current Differential / Overcurrent Relay provides protection for any two-input apparatus such as transformers, motors, generators, and reactors. Apply it for differential and overcurrent protection and use event reports for quick post-event analysis.

SEL-787-3/-4 Transformer Protection Relay

Protect and monitor most three- and four-terminal transformers with the versatile SEL-787 Transformer Protection Relay platform. Select SEL-787-3E/-3S models, and apply three-phase current and voltage inputs with options for either a single-phase restricted earth fault (REF) input or a single-phase voltage input for comprehensive transformer protection.

SEL-787 Transformer Protection Relay

Protect and monitor most industrial transformer applications with the versatile SEL-787 Transformer Protection Relay. Apply 2 three-phase winding inputs, and an optional single-phase restricted earth fault input and three-phase voltage inputs for comprehensive transformer protection.

SEL-2600 RTD Module

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SEL-2600 RTD is a microprocessor-based module, which can measure and transmit data from up to 12 RTDs and a single contact status located in transformers, breakers, motors, generators, or other system apparatus.


487E 387E 387 387A 787 787-3E 787-3S 787-4X 587
Breaker Failure Protection f f f f
Transformer and Machine Current Differential
Low-Impedance Bus Differential
Underfrequency Load Shedding f +
Undervoltage Load Shedding f +
Three-Phase Current Inputs 5 3 4 2 2 3 3 4 2
Three-Phase Voltage Inputs 2 1 1+ 1 1
24 Overexcitation (Volts/Hertz) +
25 Synchronism Check
27/59 Under-/Overvoltage +
32 Directional Power +
46 Current Unbalance
49 Equipment Thermal Monitoring +
50FO Flashover Protection f f f f f f
50 (N,G) Overcurrent (Neutral, Ground)
50P Phase Overcurrent
50Q Negative-Sequence Overcurrent
51 (N,G) Time-Overcurrent (Neutral, Ground)
51P Phase Time-Overcurrent
51Q Negative-Sequence Time-Overcurrent
67 (P,G,Q) Directional Overcurrent (Phase, Ground, Neg. Seq.)
81 Under-/Overfrequency +
81R Change-in-Rate-of-Frequency f
87 Current Differential
REF Restricted Earth Fault + +
SELogic Control Equations
Voltage Check on Closing f f f
Transformer Cooling Fan Control f f f f f
Nonvolatile Latch Control Switches
SELogic Remote Control Switches
SELogic Local Control Switches
Display Points
Multiple Settings Groups
Substation Battery Monitor
Breaker Wear Monitor
Event Report (Multicycle Data)
Sequential Events Recorder
Instantaneous Meter
Demand Meter
Load and Temperature Profile Report
RTD (Resistance Temperature Detector) Inputs + + + +
Built-In Web Server
IEEE C37.118 Synchrophasors
IEC 61850 + + + + + +
IEC 60870-5-103 + + +
Simple Network Time Protocol (SNTP)
Parallel Redundancy Protocol (PRP)
Through-Fault Monitor +
2600 RTD Module Communications
Thermal Model +
Connectorized (Quick Disconnect) Available + + + + + + +
Standard Feature
+ Model Option
f This function may be created using settings