Maintenance; Output Matrix Test; Cb Counters; Cb Wear - Siemens 7SR242 Duobias Technical Manual

6.3

Maintenance

6.3.1 Output Matrix Test

The feature is available from the Relay fascia and allows the user to operate binary outputs or LEDs assigned to
relay functions.
Any protection function which is enabled in the setting menu will appear in the Output Matrix Test.

6.3.2 CB Counters

Four CB trip counters are provided:
CB1 Total Trip Count:
CB1 Delta Trip Count:
CB2 Total Trip Count
CB2 Delta Trip Count:
The status of each counter can be viewed in the INSTRUMENTS mode.
Binary outputs can be mapped to each of the above counters, these outputs are energised when the
user defined Count Target is reached.
2
6.3.3 I t CB Wear
CB1 and CB2 wear counters are also provided:
2
I t CB1 Wear:
2
I t CB2 Wear:
The status of each counter can be viewed in the INSTRUMENTS mode.
Binary outputs can be mapped to each of the above counters, these outputs are energised when the
user defined Alarm Limit is reached.
©2015 Siemens Protection Devices Limited
Chapter 1) 7SR242 Duobias Description Of Operation
Increments on each trip command issued.
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.
As CB1
As CB1
Provides an estimate of contact wear and maintenance
requirements. The algorithm works on a per phase basis,
measuring the arcing current during faults. The I
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.
As CB1
t value at
2
Chapter 1 Page 54 of 60