Hitachi Relion 650 Series Technical Manual page 313

1MRK 511 557-UEN Rev. A
ACBMSCBR calculates contact ablation as the number of equivalent mechanical operations lost
during a CB opening operation, according to the model explained above. All ablation related
calculations are performed only when Ablation is set to "Enable". For calculating the contact ablation
in the last CB opening operation, the interrupted current is integrated over the arcing time, ʃ Iⁿ dt. In
the function, this integration is performed numerically on the arcing current samples (samples after
mechanical contact separation till final current interruption); the integrated arcing current is calculated
as:

I
IECEQUATION19106 V1 EN-US
where i
1
given by CumCurrPower.
From that, ablation is calculated according to the range of integrated current, as shown in
The lower range boundary IntTh1 is taken from the setting MinCurrentLimit, the upper boundary
IntTh2 from OverCurrentLimit. The resulting ablation value is given at the LOOPABLLX output as
equivalent mechanical operations lost during the last CB opening.
Table 279: Ablation value estimation
Range
0< ∑I< IntTh1
n
IntTh1
∑I > IntTh2
where,
C = AblationCoeff0
o
C = AblationCoeff1
1
C = AblationCoeff2
2
C = AblationCoeff3
3
C = AblationCoeff4
4
P = PowerCoeff1
1
P = PowerCoeff2
2
P = PowerCoeff3
3
P = PowerCoeff4
4
The ablation value for the last operation is added to a cumulated ablation estimate (ABLSUMLX) to
keep track of the total contact ablation. ABLSUMLX retains the value during power loss.
Moreover, the function sets ABLSUMLX in relation to a maximum value given by AblationAlarmLevel.
The ratio is given at the ABLSUMRLX output and can be used for displaying or threshold checking of
the relative interrupter wear:
Technical Manual
n  n  n
i i i
 

1 2 3
integrated
k
, i , i , ......i are the arcing current samples, and n is the breaker type specific exponent
2 3 k
n
n
≤ ΣI ≤ IntTh2
n
© 2021 Hitachi Energy. All rights reserved.
  n
.... i
k
LOOPABLLX
1
 

P 1
 
C C I
0 1
IECEQUATION19311 V1 EN-US
AblatCalShEst
   
 
P 2 P 3
    
C I C I C
2 3 4
Section 12
Monitoring
Table 279.
 

P 4

I
307