Motor protection

Motor protection – SIPROTEC 7SK85

SIPROTEC 7SK85

The SIPROTEC 7SK85 motor protection device is designed for the protection of motors of all sizes. With its modular structure, flexibility and the powerful DIGSI 5 engineering tool, SIPROTEC 7SK85 offers future-oriented system solutions with high investment security and low operating costs. For motors in explosive environments, the SIPROTEC 7SK85 is also available with EN 60079-14 or Verband der Elektrotechnik, Elektronik und Informationstechnik 0165, Part 1 (ATEX) certification. (Currently under development)

Features & functions

Motor protection SIPROTEC 7SK85

Features

Main function:

  • Motor protection for motors of all sizes

Inputs and outputs:

3 predefined standard variants with

  • 4 current transformers,
  • 4 voltage transformers, 
  • 11 to 27 binary inputs, 
  • 9 to 17 binary outputs

Hardware flexibility:

  • Flexibly adjustable and expandable I/O quantity structure within the scope of the modular SIPROTEC 5 system. 1/6 expansion modules can be added, available with large or small display, or without display

Width of housing:

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

As standard:

Functions

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

  • Motor protection functions: Startup time monitoring, thermal overload protection for stator and rotor, restart inhibit, unbalanced-load protection, load-jam protection
  • Stator and bearing temperature monitoring via temperature sensors with external RTD unit.
  • Differential motor protection as fast short-circuit protection for motors of high power
  • Sensitive ground-fault protection (non-directional, directional) to detect stator ground faults
  • Directional and non-directional overcurrent protection (short- circuit protection) with 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 
  • Overvoltage and undervoltage protection
  • Arc protection
  • Power protection, configurable as active or reactive power 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
  • Control, synchrocheck and switchgear interlocking protection
  • Graphical logic editor to create powerful automation functions in the device
  • Integrated electrical Ethernet RJ45 for DIGSI 5 and IEC 61850 (reporting and GOOSE)
  • Up to 4 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)
  • 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
  • Secure serial protection data communication, also over great distances and all available physical media (optical fiber, two-wire connections and communication networks)
  • Capturing operational measured variables and protection function measured values for the evaluation of the systems,to support commissioning, and to analyze faults
  • Synchrophasor measured values with the IEEE C37.118 Phasor Measurement Unit (PMU)
  • 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

  • Protection against thermal overload of the stator from overcurrent, cooling problems or pollution
  • Protection against thermal overload of the rotor during startup due to: Frequent startups, excessively long startups or blocked rotor
  • Monitoring for voltage unbalance or phase outage
  • Monitoring the thermal state and the bearing temperatures with  temperature measurement
  • Detection of idling drives of pumps and compressors, for example
  • Detection of ground faults in the motor
  • Protection against motor short circuits
  • Protection against instability due to undervoltage.

Benefits

  • Safety due to powerful protection functions
  • Data security and transparency over the entire lifecycle of the plant, saving time and money
  • Purposeful and easy handling of devices and software thanks to a user-friendly design
  • Increased reliability and quality of the engineering process
  • 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
  • Full compatibility between IEC 61850 Editions 1 and 2
  • High investment security and low operating costs due to future-oriented system solutions

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