7SR210 & 7SR220 Description of Operation
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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.
The above counters can be triggered and reset from a binary input or command.
6.2.1 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.
6.2.2 Output Matrix Test
The feature is only visible from the Relay fascia and allows the user to operate the relays functions. The test of
the function will automatically operate any Binary Inputs or LED’s already assigned to that function. Any protection
function which is enabled in the setting menu will appear in the Output Matrix Test.
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