7SR11 & 7SR12 Description Of Operation
©2017 Siemens Protection Devices Limited Chapter 1 Page 81 of 88
6.3.2 CB COUNTERS
The following CB maintenance counters are provided:
Increments on each trip command issued.
CB Total Trip Manual Open Selects whether the CB Total Trip Counter is incremented for
Manual Open Operations. If disabled, the CB Total Counter
will only increment for protection trip commands.
CB Delta Trip Count: Additional counter which can be reset independently of the
Total Trip Counter. This can be used, for example, for
recording trip operations between visits to a substation.
CB Delta Trip Manual Open Selects whether the CB Delta Trip Counter is incremented for
Manual Open Operations. If disabled, the CB Delta Trip
Counter will only increment for protection trip commands.
CB Count to AR Block: (Only in Auto-reclose
models)
Displays the number of CB trips experienced by the CB
before the AR is blocked. When the target is reached the
relay will only do 1 Delayed Trip to Lockout. An output is
available to reset this value.
CB Count to AR Block Manual Open: (Only in
Auto-reclose models)
Selects whether the CB Count to AR Block is incremented for
Manual Open Operations. If disabled, the CB Count to AR
Block will only increment for protection trip commands.
CB Frequent Ops Count Logs the number of trip operations in a rolling window period
of one hour. An output is available to reset this counter.
Binary outputs can be mapped to each of the above counters, these outputs are energised when the user
defined Count Target or Alarm Limit is reached.
6.3.3 I
2
T CB WEAR
An I
2
t counter is also included, this can provide an estimation of contact wear and maintenance requirements. The
algorithm works on a per phase basis, measuring the arcing current during faults. The I
2
t value at the time of trip
is added to the previously stored value and an alarm is given when any one of the three phase running counts
exceeds the set Alarm limit . The t value is the time between CB contacts separation when an arc is formed,
Separation Time, and the CB Clearance time.
The I
2
t value can also triggered and reset from a binary input or command.
6.4 General Pickup
The General Pickup output is provided in OUTPUT CONFIG>OUTPUT MATRIX and can be mapped to operate
any binary output, led or virtual I/O. It is operated by instantaneous pick up of protection elements without their
associated time delay. Any combination of elements can be selected to initiate General Pickup operation so that
elements used for alarm only purposes can be ignored. All available elements are listed and controlled by settings
in the OUTPUT CONFIG>PICKUP CONFIG menu, separated by type as Voltage or Frequency elements.
6.5 Data Storage
6.5.1 GENERAL
The relay stores three types of data: 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 supply voltage. The data storage menu contains the settings for the Demand, Waveform and Fault
storage features.
6.5.2 DEMAND
Maximum, minimum and mean values of line currents, voltages and power (where applicable) are available as
instruments which can be read in the relay INSTRUMENTS MENU or via Reydisp.
The Gn Demand Window setting defines the maximum period of time over which the demand values are valid. A
new set of demand values is established after expiry of the set time.
The Gn Demand Window Type can be set to FIXED or PEAK or ROLLING.
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