ABB Relion 670 Series Applications Manual page 524

Section 18
Monitoring
Even though transformer damages caused by through faults are cumulative by nature,
individual through fault events also require attention. This is because the impact of several
small through faults can be less compared to one heavy through fault.
The PTRSTHR function monitors each through fault events and accumulates the calculated
values for each fault to determine the cumulative effect. This cumulative
windings phase-wise and when this value exceeds the cumulative
raised.
MaxI2tCmlW1 : It defines the cumulative I
phase. Similarly, the cumulative threshold limit for winding 2 and winding 3 shall be set using
MaxI2tCmlW2 and MaxI2tCmlW3 settings.
The alarm signal due to individual event
or the set minimum time delay, whichever is longer. The alarm signal due to cumulative
set high continuously until the cumulative
limit.
tPulse : It defines the pulse duration for an individual event I
Consider all the calculations based on through fault not as a precise indicator of transformer
health. These values indicate that the transformer should be inspected, they do not indicate a
strict necessity to shut-down the transformer.
18.12.3.6
Initial values for cumulative
The calculated cumulative
counts can be reset with preset values using command inputs under the clear menu or via
binary inputs. The following parameters which are set under advanced parameters are related
to the initial values of cumulative
InitCI2tW1L1 : It defines the initial cumulative I
initial cumulative
designated with L2 and L3 in the parameters name. For other windings, the initial cumulative
2
I t values shall be set using the parameters which are designated with W2 and W3 in the
parameters name.
InitTFCntW1L1 : It defines the initial fault counter value of winding 1 and phase L1. Similarly, the
initial fault counter value for other phases L2 and L3 shall be set using parameters which are
designated with L2 and L3 in the parameters name. Also, for other windings the initial fault
counter value shall be set using the parameters which are designated with W2 and W3 in the
parameters name.
InitCmlTFCnt : It defines the initial overall fault counter value for the transformer.
18.12.4 Setting examples
In order to correctly apply transformer through fault monitoring with proper zero sequence
current, correction is needed for:
• Power transformer phase shift (vector group compensation)
• Zero sequence current (zero sequence current consideration)
The through fault monitoring is suitable for all standard three-phase power transformers
without any interposing CTs. It is designed with the assumption that all main CTs are star
connected. For such applications, it is only necessary to enter CT rated data and power
transformer data directly as they are given on the power transformer nameplate. The zero
518
2
I t and number of through faults
2
I t values for each phase of windings and number of through faults
2
I t and number of through faults.
2
I t value for L2 and L3 phase shall be set using parameters which are
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2
t threshold limit for all fault events in winding 1, per
2
I t will be reset either after the ongoing fault is cleared
2
I t values are reset to a lower value than the set
2
t alarm.
2
t value for winding 1 and phase L1. Similarly,
1MRK 511 401-UEN Rev. K
2
I t is calculated for all
2
I t set limit, an alarm is
2
I t is
GUID-AA90D6D8-4AF2-4D5D-BCD9-308CD7578D05 v1
GUID-2AE19CC1-F790-4E98-A75D-65363155E209 v1
Bay control REC670
Application manual
2
I t