ABB REL650 Applications Manual page 257

1MRK 506 334-UUS A
Application manual
Operate
Angle1(2) = 0
Power1(2)
IEC06000556 V1 EN
Figure 122: For low forward power the set angle should be 0° in the underpower
function
TripDelay1(2) is set in seconds to give the time delay for trip of the stage after pick up.
The possibility to have low pass filtering of the measured power can be made as shown in
the formula:
( )
S TD S TD S
= ⋅ + 1 − ⋅
Old Calculated
EQUATION1893-ANSI V1 EN
Where
S is a new measured value to be used for the protection function
S is the measured value given from the function in previous execution cycle
old
S is the new calculated value in the present execution cycle
Calculated
TD
is settable parameter
The value of TD=0.98 or even TD=0.99 is recommended in generator low forward power
applications as the trip delay is normally quite long. This filtering will improve accuracy
of the power function.
Q
°
en06000556.vsd
Section 7
Current protection
P
(Equation 163)
251