Disturbance recorder collects analog values and binary signals continuously, in a cyclicbuffer. The pre-fault buffer operates according to the FIFO principle; old data willcontinuously be overwritten as new data arrives when the buffer is full. The size of thisbuffer is determined by the set pre-fault recording time.Upon detection of a fault condition (triggering), the disturbance is time tagged and the datastorage continues in a post-fault buffer. The storage process continues as long as the faultcondition prevails - plus a certain additional time. This is called the post-fault time and itcan be set in the disturbance report.The above mentioned two parts form a disturbance recording. The whole memory,intended for disturbance recordings, acts as a cyclic buffer and when it is full, the oldestrecording is overwritten. Up to the last 100 recordings are stored in the IED.The time tagging refers to the activation of the trigger that starts the disturbance recording.A recording can be trigged by, manual start, binary input and/or from analog inputs (over-/underlevel trig).A user-defined name for each of the signals can be set. These names are common for allfunctions within the disturbance report functionality.14.9.5.1 Memory and storageThe maximum number of recordings depend on each recordings totalrecording time. Long recording time will reduce the number of recordingsto less than 100.The IED flash disk should NOT be used to store any user files. This mightcause disturbance recordings to be deleted due to lack of disk space.When a recording is completed, a post recording processing occurs.This post-recording processing comprises:• Saving the data for analog channels with corresponding data for binary signals• Add relevant data to be used by the Disturbance handling tool (part of PCM 600)• Compression of the data, which is performed without losing any data accuracy• Storing the compressed data in a non-volatile memory (flash memory)The recorded disturbance is now ready for retrieval and evaluation.The recording files comply with the Comtrade standard IEC 60255-24 and are dividedinto three files; a header file (HDR), a configuration file (CFG) and a data file (DAT).1MRK 502 048-UUS A Section 14Monitoring583Technical manual
