Hitachi Relion 670 Series Applications Manual page 152

Section 8
Current protection
IEC06000556 V1 EN-US
Figure 71:
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 69.
=
S
N
EQUATION2047 V1 EN-US
The drop out power will be Power1(2) + Hysteresis1(2).
The possibility to have low pass filtering of the measured power can be made as shown in the formula:
S TD S
= ⋅
EQUATION1893-ANSI V1 EN-US
Where
S
S
old
S
Calculated
TD
The value of k=0.92 is recommended in generator applications as the trip delay is normally quite long.
The calibration factors for current and voltage measurement errors are set % of rated current/voltage:
IMagComp5, IMagComp30, IMagComp100
VMagComp5, VMagComp30, VMagComp100
146
Q
Operate
Angle1(2) = 0
Power1(2)
For low forward power the set angle should be 0° in the underpower function
× ×
3 VBase IBase
( )
TD S
+ 1 − ⋅
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
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°
P
en06000556.vsd
1MRK511407-UUS Rev. N
(Equation 69)
(Equation 70)
Phasor measurement unit RES670
Application manual