The measuring devices of the SHERLOG range combine the monitoring functions of a high-class digital fault recorder with the features of a power quality analyser in a single system. They can be used to comprehensively monitor power engineering equipment such as lines and bus bars and associated protection devices and switchgear equipment.

As well as detecting faults and making high-resolution recordings of the signal characteristics in fault records, SHERLOG systems can also make long-term recordings of RMS value characteristics and calculate all the relevant power system parameters needed in order to determine and monitor power quality.

Because SHERLOG devices can be networked easily, it is possible to create highly complex measuring systems which are capable of monitoring any number of bus bars and lines.

SHERLOG can be used to monitor power systems precisely and reliably. As SHERLOG systems are entirely digital, their functioning is fully software-controlled. All processes and functions are freely programmable. New function modules or algorithms which meet new standards can easily be added during manual or automatic software maintenance.

Fields of application

SHERLOG systems are suitable for all voltage levels. They can be used as centralized or decentralized monitoring systems and unite the following functions in one device:

  • High-resolution fault recorder for transient processes with sampling rates up to 30 kHz
  • RMS recorder
  • Continuous data recorder
  • Event recorder
  • Power quality analyser to IEC61000-4-30 class A
  • Fault locator
  • Phasor measurement unit
  • Sequence of events recorder
  • Integration in substation control and protection systems to IEC 61850

Examples of applications:   

  • Digital fault recorder with a high sampling frequency for detailed analysis of transient faults
  • Generator monitoring in power plants
  • Recording and identification of power swings
  • Power quality analysis, e.g. to EN 50160
  • Load and frequency recording
  • Analysis of power consumption
  • Assessment of the capacity utilisation and stability of supply systems
  • Capture of influences resulting from a constantly fluctuating generator and load structure
  • Monitoring of individually agreed connection conditions for compliance with limit values
  • Documentation system for commissioning and service tests
  • Chronological event recording and logging of binary status signals

Safe and efficient

  • Because SHERLOG fault recorders contain no parts which are subject to wear and tear, such as hard disk memory or fans, they are 100% maintenance-free.
  • Galvanic separation of all measurement inputs and communication interfaces for maximum flexibility and safe operation.
  • Measurement data is saved reliably in the internal data memory and is not lost in the event of a power failure or when the device is switched off.

Advantages over digital protection relays

  • Because comprehensive trigger criteria can be set independently of the protection function, it is possible to record even very slight anomalies in the supply system
  • Unadulterated signal recording thanks to the broad bandwidth from DC to 15 kHz
  • Identification of malfunctioning transducers, bad switching contacts or ferroresonance
  • Simultaneous recording with fast sampling for detailed fault analysis and slow sampling for the identification of power swings and for the performance of stability evaluations
  • Recordings include information on all plant components and their impact chain
  • By recording data continuously in order to monitor power system operation comprehensively, proof of how a power system is operating can be provided at any time, even if no disturbances were detected during the period in question
  • Exhaustive evaluation of power quality, including harmonic and flicker analysis to IEC 61000-4-30 class A, IEC 61000-4-7, IEC61000-4-15