Transformer differential protection SIPROTEC 7UT87

Transformer differential protection SIPROTEC 7UT87

Product Overview

Modular SIPROTEC 7UT87 transformer differential protection relay for the protection of multi-winding transformers with up to 5 sides.

Features :

Main function:

  • Up to 3 differential protection functions with additional stabilization (in different transformer function groups); up to 5 ground fault differential protection functions.
  • For auto transformer applications, two differential protection functions can be processed in an Auto transformer function group.
  • Interoperability of SIPROTEC 5 and SIPROTEC 4 line protection devices

Usable measuring points:

  • 9 x 3-phase current measuring points,
  • 5 x 1- phase current measuring points,
  • 5 x 3-phase voltage measuring points

Inputs and outputs:

2 predefined standard variants with

  • 20 current transformers,
  • 4 voltage transformers,
  • 15 to 27 binary inputs,
  • 22 to 38 binary outputs

Hardware flexibility:

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

Width of housing:

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

As standard:

Functions :

DIGSI 5 permits all functions to be configured and combined as required. In SIPROTEC 7UT87, two transformer function groups can be used.

  • Transformer differential protection for multi-winding transformers with versatile, additional protection functions (multi-winding transformers are typical in power converter applications (such as HVDC))
  • Transformer differential protection for phase angle regulating transformers of the single core and two core types, and special transformers
  • Transformer protection applications with up to 11 3-phase current measuring points
  • Simultaneous differential protection for 3 transformers (such as 3 two-winding transformers)
  • Universal usability of the permissible measuring points
  • Applicable from average up to extra high  voltage
  • Protection of standard power transformers, auto transformers, short lines, cables, for longitudinal and shunt reactors, as well as motors
  • Typical properties of a transformer differential protection  such as flexible adaptation to the transformer vector group, control of inrush and overexcitation  processes, safe behavior in case of current-transformer saturation with different degrees of saturation
  • Fault locator plus for accurate fault location with inhomogenous line sections and targeted automatic overhead-line section reclosing (AREC)
  • Arc protection
  • Voltage controller  function ANSI 90V for two-winding transformers, three-winding transformers and grid coupling transformers with parallel control (master/follower, circulating reactive current minimization)
  • Adaptive adaptation of the operate curve to the transformer tap position
  • Increased sensitivity with near-neutral-point ground faults through a separate restricted ground-fault  protection
  • Point-on-wave switching
  • Additional current and voltage inputs can be supplements for standard protection functions, such as overcurrent, voltage frequency, etc.
  • Dynamic Voltage Control (DVC) to adapt the voltage target value via a power direction dependent characteristic curve with strong infeed of regenerative energies
  • Graphical logic editor to create powerful automation functions in the device
  • Up to 4 pluggable communication modules, usable for different and redundant protocols (IEC 61850-8-1, IEC 61850-9-2 Client, IEC 60870-5-103, IEC 60870-5-104, Modbus TCP, DNP3 serial and TCP, PROFINET IO, PROFINET IO S2 redundancy)
  • Virtual network sharing (IEEE 802.1Q – VLAN)
  • Reliable data transmission via PRP and HSR redundancy protocols
  • Extensive cybersecurity functionality, such as role-based access control (RBAC), protocolling security-related events, signed firmware or authenticated network access IEEE 802.1X
  • Simple, quick and secure access to the device via a standard Web browser to display all information and diagnostic data, as well as vector diagrams, single-line and device display pages
  • Secure serial protection data communication, also over great distances and all available physical media (optical fiber, two-wire connections and communication networks)
  • PQ-Basic: voltage unbalance; voltage changes: overvoltage, dip, interruption; TDD, THD and Harmonics
  • Capturing operational measured variables and protection function measured values for the evaluation of the system, to support commissioning, and to analyze faults
  • Frequency tracked protection functions over a wide frequency range (10 Hz to 90 Hz) and the option to assign the protection functions in a single device to different frequency tracking groups
  • Phasor Measurement Unit (PMU) for synchrophasor measured values and IEEE C37.118 protocol
  • 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

More Information


+66 2 063 5262-3, +66 83 440 1404