ABB Relion REC670 Applications Manual page 168

Section 7
Current protection
IEC06000557 V2 EN-US
Figure 75: For reverse power the set angle should be 180° in the overpower function
TripDelay1(2) is set in seconds to give the time delay for trip of the stage after pick up.
Hysteresis1(2) is given in p.u. of generator rated power according to equation 87.
=
S
N
EQUATION1708 V1 EN-US
The drop out power will be
The possibility to have low pass filtering of the measured power can be made as shown in the
formula:
= ×
S k S
EQUATION1893 V1 EN-US
Where
S
S
old
S
Calculated
k
The value of
quite long.
The calibration factors for current and voltage measurement errors are set % of rated current/
voltage:
162
Operate
Power 1(2)
× ×
3 UBase IBase
Power1(2) - Hysteresis1(2) .
( )
+ - ×
1 k S
Old Calculated
is a new measured value to be used for the protection function
is the measured value given from the function in previous execution cycle
is the new calculated value in the present execution cycle
is settable parameter
k = 0.92 is recommended in generator applications as the trip delay is normally
Q
o
Angle1(2 ) = 180
IEC06000557-2-en.vsd
1MRK 511 358-UEN A
P
(Equation 87)
(Equation 88)
Application manual