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Recording functions of EPPE and SHERLOG systems
Fast fault recording
When a limit value violation occurs, all analog and binary signals are recorded with a configurable resolution of 100 Hz to 30 kHz. The recording includes separately configurable time windows for pre-fault, fault and post-fault periods. A special mode can be used to control the length of the fault recording period in accordance with the actual duration of the limit value violation. This method provides maximum information with minimum data volume.
Slow fault recording
In addition to the analog and digital signals which are measured directly, the RMS recorder function also records all the quantities calculated on the basis of these signals, such as frequency, unbalance, positive sequence system, negative sequence system and zero sequence system, active power, reactive power and apparent power, harmonics etc. The sample rate can be set between 1 Hz and double the system frequency (100 Hz/120 Hz). Each recording can include up to 30 seconds pre-fault time and 15 seconds post-fault time. This method is ideal for detecting and assessing slow processes such as power swings.
Continuous data recording
The data logger function records measurement data continuously. The recorded data can be downloaded to a central computer without interrupting the measurement. As a result, data can be recorded continuously for a number of years. The averaging intervals can be set between one second and 24 hours. For each averaging interval, the mean RMS value and the largest and smallest single RMS values are recorded with an exact time stamp.
Up to 8 different averaging intervals, each with up to 500 selectable measurement quantities, can be recorded simultaneously. Long-term recordings provide comprehensive information on the entire power system, expose slow changes, as can result from a changing load or generator structure, and reveal potential for energy savings.
Event recording provides information on the time, level and duration of limit value violations and a classification of events to EN 50160, for example. If required, the event signatures can also be recorded with a time resolution of half a period. To keep memory requirements to a minimum, the sample rate can also be controlled dynamically. Fast signal changes are recorded with a higher resolution than slow signal changes.
Power quality recording
The continuous recording of all power system parameters allows comprehensive power quality analysis to DIN EN 50160 or quality criteria defined by the individual user. Characteristic values are captured and calculated to IEC 61000-4-30 class A, IEC 61000-4-7 and IEC 61000-4-15. Because quality reports can be created automatically as PDF files, it is easy to provide proof of quality whenever required, even without specialist knowledge.
Recording digital events and states
Binary inputs are primarily used to read in signals from protection relays and circuit breaker positions which are of decisive importance for the analysis of fault records.
Event classes with and without an acknowledgement obligation and message texts which can be listed or printed out chronologically can be assigned to the binary inputs for the continuous recording of binary signals (SER function).
Power quality analysis and fault analysis with full area coverage call for precise time synchronisation. Only when measured values are recorded by a number of devices absolutely simultaneously, is it possible to compare them with one another and evaluate them correctly.
This makes it possible to identify weak points in the supply system and remedy them efficiently.
EPPE and SHERLOG systems can be synchronised with GPS, DCF 77 and NTP and for seconds or minutes pulses, so all common time synchronisation methods are available.
Using the KoCoS synchronisation bus, any number of devices can be synchronised using a simple 2-wire connection. This leads to significant cost savings as only one measuring device per location needs to be synchronised against a precise time basis. This "master system" then synchronises all the other KoCoS measuring systems.
Inputs and outputs
All analog and binary outputs and all interfaces are galvanically isolated and meet stringent occupational health and safety requirements. They also feature excellent immunity from electro-magnetic disturbances. Because of the absolutely linear frequency response, all the analog inputs are suitable for ac or dc quantities however they are configured and provide high accuracy across the entire measuring range.
The special input circuitry of the binary inputs is designed for operation with voltages between 24 V and 300 V and effectively suppresses the detection of transients which can be caused by switching operations, for example. Freely configurable relay outputs can be used to indicate status signals, alarm signals or limit value violations to control systems, for example.