7SR210 & 7SR220 Description of OperationUnrestricted ©2018 Siemens Protection Devices Limited Page 89 of 946.3 Data Storage6.3.1 GeneralThe relay stores three types of data records: relay event records, analogue/digital waveform records and faultrecords. Data records are backed up in non-volatile memory and are permanently stored even in the event of lossof auxiliary d.c. supply voltage.6.3.2 Event RecordsThe event recorder feature allows the time tagging of any change of state (Event) in the relay. As an eventoccurs, the actual event condition is logged as a record along with a time and date stamp to a resolution of 1millisecond. There is capacity for a maximum of 5000 event records that can be stored in the relay and when theevent buffer is full any new record will over-write the oldest. Stored events can be erased using the DATASTORAGE>Clear Events setting.The following events are logged: -Change of state of Binary outputs.Change of state of Binary inputs.Change of Settings and Settings Group.Change of state of any of the control functions of the relay.Protection element operation.All events can be blocked or made available and uploaded over the data communications channel(s) and can bedisplayed in the ‘Reydisp Evolution’ package in chronological order, allowing the sequence of events to beviewed. Events are also made available spontaneously to an IEC 60870-5-103, Modbus RTU or DNP3.0compliant control system. The function number and event number can also be changed. The events are selectedand edited using the Reydisp software tool.6.3.3 Waveform Records.Waveform records provide a trace of the instantaneous magnitude of each analogue input channel and the statusof each binary channel i.e. each binary input, binary output, virtual I/O and LED, against time for the duration ofthe record. The values are recorded at every digital sampling point used by the relay software.Each recorded analogue waveform displays an input identifier, minimum value, maximum value and theinstantaneous values at both cursor positions (user variable). Each binary waveform displays the input/outputnumber and the initiating condition(s) e.g. external input or protection element.Triggering of waveform storage is configured from the ‘Settings > DATA STORAGE > WAVEFORM STORAGE’menu. Triggering is automatically initiated from operation of any of the selected protection or control elements.Waveform storage can also be triggered from the relay fascia, from a suitably programmed binary input or via thedata comms channel(s).Waveforms are sampled at a rate of 32 samples per cycle.The latest 10 records are stored; the most recent is waveform 1. Records are archived by the relay duringquiescent periods. The duration of each stored record is 1s, 2s, 5s or 10s. The user can also specify thepercentage of waveform storage prior to waveform triggering. When the waveform archive buffer is full (i.e. 10records are stored) the triggering of a new waveform record causes the oldest record - waveform 10 – to beoverwritten.Stored waveforms can be deleted from the relay fascia using the DATA STORAGE > Clear Waveforms setting orvia Reydisp.
