ABB REQ650 - Breaker Failure Protection (CCRBRF, CSPRBRF)

The residual power, measured by the sensitive earth-fault protections in A and B will
be:
0A 0A 0
S 3U 3I= ×
EQUATION1951 V1 EN (Equation 37)
0B 0 B 0
S 3U 3I= ×
EQUATION1952 V1 EN (Equation 38)
The residual power is a complex quantity. The protection will have a maximum
sensitivity in the characteristic angle RCA. The apparent residual power component
in the characteristic angle, measured by the protection, can be written:
0A ,prot 0A 0 A
S 3U 3I cos
j = × ×
EQUATION1953 V1 EN (Equation 39)
0B,prot 0B 0 B
S 3U 3I cos j = × ×
EQUATION1954 V1 EN (Equation 40)
The angles φ
A
and φ
B
are the phase angles between the residual current and the
residual voltage in the station compensated with the characteristic angle RCA.
The protection will use the power components in the characteristic angle direction for
measurement, and as base for the inverse time delay.
The inverse time delay is defined as:
0 0
inv
0 0
kSN (3I 3U cos (reference))
t
3I 3U cos (measured)
× × × j
=
× × j
EQUATION1942 V2 EN (Equation 41)
GlobalBaseSel: Selects the global base value group used by the function to define
(IBase), (UBase) and (SBase).
The function can be set On/Off with the setting of Operation.
With the setting OpMode the principle of directional function is chosen.
With OpMode set to 3I0cosfi the current component in the direction equal to the
characteristic angleRCADir has the maximum sensitivity. The characteristic for
RCADir is equal to 0° is shown in figure
63.
1MRK 505 291-UEN A Section 6
Current protection
127
Application manual