Siemens Reyrolle 7SR5 Manual page 386

Control Functions
7.2 52 Circuit-Breaker Control
Parameter: CB-n Counters > Total Trip Count Target
•
Default setting: 100
Increments on each trip command issued.
Parameter: CB-n Counters > Delta Trip Count Target
•
Default setting: 100
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.
Parameter: CB-n Counters > Frequent Ops Count Target
•
Default setting: 10
Logs the number of trip operations in a rolling window period of 1 hour. An input is available to reset this
counter.
Parameter: CB-n Counters > CB Count to 79 Block Man Open
•
Default setting: Disabled
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.
Parameter: CB-n Counters > CB Count to 79 Block Target
•
Default setting: 100
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.
Parameter: CB-n I
•
Default setting: 10 MA
The I 2 t counter provides an estimate of the CB contact wear, from this planned maintenance of the CB
can be scheduled. The setting is in primary current so the effect of the CT ratios must be considered.
The algorithm works on a per phase basis, measuring the CB contact arcing current measured during CB
opening to clear the fault. Arcing current flows from the point of contact separation until the fault is
cleared. The I
when any one of the 3 phase running counts exceeds the Alarm Limit setting. The value for t is calcu-
lated from:
t = Clearance Time - (Contact) separation time
See below for the user set values of separation time and clearance time.
The I 2 t value can also triggered and reset from a binary input or command.
Parameter: CB-n I
•
Default setting: 0.02 s
The user set value for the (contact) separation time is the time between issue of the trip command and
separation of the CB contacts separation. This can be obtained from CB test records.
Parameter: CB-n I
•
Default setting: 0.04 s
The user set value for the clearance time is the time between issue of the trip command and interruption
(clearance) of the fault current. This can be obtained from CB test and operational records.
386
2 T Wear > Alarm Limit
2 s
2 t value at the time of trip is added to the previously stored value and an alarm is given
2 T Wear > Separation Time
2 T Wear > Clearance Time
Reyrolle 7SR5, Transformer Protection Device, Device Manual
C53000-G7040-C015-1, Edition 11.2019