Data Storage; General; Demand / Data Log; Event Records - Siemens 7SR21 Manual

6.3

Data Storage

6.3.1

General

The relay stores three types of data records: relay event records, analogue/digital waveform records and fault
records. Data records are backed up in non-volatile memory and are permanently stored even in the event of loss
of auxiliary d.c. supply voltage.
6.3.2

Demand / Data Log

The Demand / Data log feature can be used to build trend and maximum/minimum demand records. Up to 10,080
individual time stamped records can be stored at a user defined rate e.g. 7 days @ 1 minute intervals and > 1
year @ 1 hour intervals.
Maximum, minimum and mean values of line current, voltage and power (where applicable) are available as
instruments which can be read in the relay INSTRUMENTS MENU or via Reydisp Evolution.
In the menu DATA STORAGE > DEMAND / DATA LOG: -
The Data Log Period setting is used to define the period between stored samples.
The Gn Demand Window setting defines the maximum period of time over which the demand values are
calculated. A new set of demand values is established after expiry of the set time.
The Gn Demand Window Type is the mode used to calculate demand values and can be set to FIXED or
PEAK or ROLLING: -
When set to FIXED the maximum, minimum and mean values demand statistics are calculated over
fixed Window duration. At the end of each window the internal statistics are reset and a new window
is started.
When set to PEAK the maximum and minimum values since the feature was reset are recorded.
When set to ROLLING the maximum, minimum and mean values demand statistics are calculated
over a moving Window duration. The internal statistics are updated when the window advances.
The statistics can be reset from a binary input or communication command, after a reset the update period and
window are immediately restarted.
6.3.3

Event Records

The event recorder feature allows the time tagging of any change of state (Event) in the relay. As an event
occurs, the actual event condition is logged as a record along with a time and date stamp to a resolution of 1
millisecond. There is capacity for a maximum of 5000 event records that can be stored in the relay and when the
event buffer is full any new record will over-write the oldest. Stored events can be erased using the DATA
STORAGE>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 be
displayed in the 'Reydisp Evolution' package in chronological order, allowing the sequence of events to be
viewed. Events are also made available spontaneously to an IEC 60870-5-103, Modbus RTU or DNP3.0
compliant control system. The function number and event number can also be changed. The events are selected
and edited using the Reydisp software tool.
For a complete listing of events available in each model, refer to Technical Manual section 4 'Data
Communication Definitions'.
©2010 Siemens Protection Devices Limited
7SR21 & 7SR22 Argus Description of Operation
Chapter 1 Page 67 of 71