7SG12 DAD N Description of Operation
The Trip Circuit Timer(s) are inhibited whenever one or more of the status inputs selected is energised.
4 Other Features
4.1 Metering
The metering feature provides real-time data available from the relay fascia in the ‘Instruments Mode’ or
via the communications interface.
The following displays are available:
Differential currents (Primary and secondary)
Digital input status
Output relay status
Time and Date
4.2 Data Storage
4.2.1 General
Details of relay operation are recorded in three forms, namely Waveform records, Event records and Fault
Data records. All records are time and date stamped with a resolution of one millisecond.
4.2.2 Waveform Records.
The waveform record feature stores analogue and digital information for the current inputs, status inputs
and output relays and LED’s. Waveforms may be returned to VA TECH Reyrolle ACP Ltd for analysis.
The waveforms are stored with a sampling resolution of at least 16 samples per cycle depending upon
relay model. The waveform recorder has the ability to store records for the previous four trip operations of
the relay. These are labelled 1-4 with 1 being the most recent record. This however, can be altered using
the ‘Record Duration’ setting, which offers the following selection:
•
Five records of one second duration
•
Two records of two seconds duration
•
One record of five seconds duration
The waveform recorder will be triggered automatically when any protection element operates. It can also
be triggered by any of the following means:
Via the ‘Trigger Storage” status input signal.
Via the IEC870-5-103 communications interface.
The waveform recorder has a settable pre-fault triggering capability.
4.2.3 Event Records
The event recorder feature allows the time tagging of any change of state (Event) of 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 500 event records that can be stored in the relay and
when the event buffer is full any new record will over-write the oldest. The following events are logged:
Change of state of Output Relays.
Change of state of Status Inputs.
Change of Settings and Settings Group
Change of state of any of the control functions of the relay.
4.2.4 Fault Recording
The fault type, led flag configuration, date and time of the last five faults are recorded for display via the
Fascia LCD.
Note : the real-time clock, waveform records, fault records and event records are all maintained, in the
event of loss of auxiliary d.c. supply voltage, by the backup storage capacitor. This capacitor has the ability
©2010 Siemens Protection Devices Limited
Chapter 1 Page 6 of 14
Summary of Contents for 7SG12 DAD-N
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