SEL-787
Transformer Protection Relay
SEL Advances the State of the Art
in Transformer Protection
• Synchrophasors detect system oscillations and potential
instability.
• Mirrored Bits® communications is ideal for teleprotection
and remote control applications.
• Flexible communications make control integration fast
and easy.
• Small form factor speeds new installations and retrofits
of electromechanical relays.
• Commissioning Assistant is the first transformer relaying
software that recommends correction settings after
identifying errors.
Optimize the Life of Your Transformers
by Monitoring Key Health Indicators
Flexible Communications
Single or Dual
Copper or Fiber
Ethernet Port
Three or Four*
Serial Ports
Cumulative Through-Fault Current Recording
Measurement and Logic Input
Use Commissioning Assistant
to Easily Generate Differential
Compensation Settings
*Optional
Industry-Leading Quality, Reliability,
and Customer Service
—40°C
+85°C
Making Electric Power Safer, More Reliable, and More Economical ®
Functional Overview
SEL-787 Transformer Protection Relay
Voltage Input
3
59
P
Q
Overvoltage
• Phase
• Neg. Seq.
P
3
27
P
Undervoltage
• Phase
P
50 QG
51 G
Q
BF
81
24
Volts/Hertz
Frequency
• Over
• Under
49
Loss-of-Potential
• Sequential Events Recorder
• SEL ASCII, Ethernet*, Modbus TCP*, IEC 61850*, DNP3 LAN/WAN*,
DNP3 Serial*, Modbus RTU, Telnet*, FTP*, and SNTP*
• Synchrophasor Data and IEEE C37.118-Compliant Protocol
• Front-Panel LED Programmable Targets
87
Temperature
Alarm and Trip
LOP
• Event Reports
32
Overcurrent
Time-Overcurrent Directional
• Phase
• Phase
Power
• Ground
• Ground
• Neg. Seq.
• Neg. Seq.
• Breaker Failure
Internal or External
RTD Inputs
O
U
Current
Differential
• Two Inputs and Three Outputs Standard
• I/O Expansion*—Additional Contact Inputs, Contact Outputs, Analog
Inputs, Analog Outputs, and RTD Inputs
• Single or Dual Ethernet Copper or Fiber-Optic Communications Port*
52
1
3
50N
51N
Neutral
Overcurrent
Neutral
Time-Overcurrent
50
P
G
Q
BF
P
51 G
Q
Overcurrent
Time-Overcurrent
• Phase
• Phase
• Ground
• Ground
• Neg. Seq.
• Neg. Seq.
• Breaker Failure
87G
Restricted Earth
Fault (REF)
• Battery-Backed Clock, IRIG-B Time Synchronization
• Instantaneous Metering
• Programmable Pushbuttons and LED Indicators
• Through-Fault Monitoring
• Advanced SELOGIC® Control Equations
• 32 Programmable Display Messages
• MIRRORED BITS Communications
• Transformer Thermal Monitoring
*Optional Functions
Ordering Options
Feature Overview
Power supply options
include 24—48 Vdc or
110—250 Vdc/110—240 Vac.
Optional Modbus TCP,
Telnet, FTP, IEC 61850, and
DNP3 LAN/WAN.
Mirrored Bits
communications.
Single or dual copper
or fiber Ethernet port.
IRIG-B input.
Fiber-optic serial port.
Positions for optional
expansion cards.
Two-winding
CT inputs.
Shown with optional
RTD inputs.
Optional neutral CT
input (REF).
Optional voltage input.
• CPU Board
- Single or dual copper or fiber Ethernet port
- EIA-232 or EIA-485 rear port
- IRIG-B input
• Optional Expansion Cards
- 3 digital inputs/4 digital outputs/4—20 mA
analog output
- 4 digital inputs/4 digital outputs
(electromechanical)
- 4 digital inputs/4 digital outputs
(fast, high-current interrupting)
- 4 analog inputs/4 analog outputs
- EIA-232 or EIA-485 serial communication
- 8 digital inputs
- 10 RTD inputs
- Neutral ac current input
- Neutral ac current input/three-phase ac
voltage (300 Vac) input
• Conformal Coating
Pullman, Washington USA
Tel: +1.509.332.1890 • Fax: +1.509.332.7990 • www.selinc.com • info@selinc.com
© 2007–2019 by Schweitzer Engineering Laboratories, Inc. PF00167 • 20190404