Line differential protection

Line differential protection – SIPROTEC 7SD87

SIPROTEC 7SD87

The SIPROTEC 7SD87 differential protection device is suitable for the selective protection of overhead lines and cables with single-ended and multi-ended infeed of all lengths with up to 6 ends. Transformers and compensating coils in the protection range are also possible. With its modular structure, flexibility and the powerful DIGSI 5 engineering tool, the SIPROTEC 7SD87 device offers future-oriented system solutions with high investment security and low operating costs.

Features & functions

Line differential protection SIPROTEC 7SD87

Features

Main function:

Tripping:

  • 1-pole and 3-pole, minimum tripping time: 9 ms

Inputs and outputs:

12 predefined standard variants with

  • 4/4 or 8/8 current transformers / voltage transformers, 
  • 5 to 31 binary inputs, 
  • 8 to 46 binary outputs

Hardware flexibility:

  • Flexibly adjustable I/O quantity structure within the scope of the SIPROTEC 5 modular system

Housing width:

  • 1/3 × 19 inches to 2/1 × 19 inches

As standard:

Functions

DIGSI 5 permits all functions to be configured and combined as required.

  • Minimum tripping time: 9 ms
  • Main protection function is differential protection with adaptive algorithm for maximum sensitivity and stability even with the most different transformer errors, current-transformer saturation and capacitive charging currents
  • Directional backup protection and various additional functions
  • Detection of ground faults of any type in compensated or isolated electrical power systems using the following functions: 3I0>, V0>, fleeting contact, cos φ, sin φ, harmonic, dir. Detection of intermittent ground faults and admittance
  • Ground fault detection using the pulse detection method
  • Detection of current-transformer saturation
  • Arc protection
  • Automatic frequency relief for underfrequency load shedding, taking changed infeed conditions due to decentralized power generation into consideration
  • Power protection, configurable as active or reactive power protection
  • Directional reactive power undervoltage protection (QU protection)
  • Detection of current and voltage signals up to the 50th harmonic with high accuracy for selected protection functions (such as thermal overload protection) and operational measured values
  • 1-/3-pole automatic reclosing function
  • Point-on-wave switching
  • Control, synchrocheck and switchgear interlocking protection
  • Graphical logic editor to create powerful automation functions in the device
  • Single-line representation in small or large display
  • Integrated electrical Ethernet RJ45 for DIGSI 5 and IEC 61850 (reporting and GOOSE)
  • Up to 4 optional pluggable communication modules, usable for different and redundant protocols (IEC 61850-8-1, IEC 61850-9-2, IEC 60870-5-103, IEC 60870-5-104, Modbus TCP, DNP3 serial and TCP, PROFINET IO)
  • Serial protection data communication via optical fibers, two-wire connections and communication networks (SDH networks, MPLS electrical power systems, for example using IEEE C37.94, and others), including automatic switchover between ring and chain topology.
  • Reliable data transmission via PRP and HSR redundancy protocols
  • Extensive cyber security functionality, such as role-based access control (RBAC), protocolling security-related events or signed firmware
  • Simple, quick and secure access to device data via a standard Web browser – without additional software
  • Phasor measurement unit (PMU) for synchrophasor measured values and IEEE C37.118 protocol
  • Time synchronization using IEEE 1588
  • Powerful fault recording (buffer for a max. record time of 80 sec. at 8 kHz or 320 sec. at 2 kHz)
  • Auxiliary functions for simple tests and commissioning
  • Flexibly adjustable I/O quantity structure within the scope of the SIPROTEC 5 modular system

Applications

Benefits

  • Safety due to powerful protection functions
  • Purposeful and easy handling of devices and software thanks to a user-friendly design
  • Cyber security in accordance with NERC CIP and BDEW Whitepaper requirements
  • Highest availability even under extreme environmental conditions  by “conformal coating“ of electronic boards
  • Powerful communication components warrant safe and effective solutions
  • High investment security and low operating costs due to future-oriented system solutions

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