n
T
T
1
V/Hz
V/Hz
D
Nominal
Measured
T
100
*
*
FST
E
D
T
T
R
R
Equation 4-13. Time to Trip
Equation 4-14. Time to Reset
where:
T
T
T
R
D
T
D
R
= Time to trip
= Time to reset
= Time dial trip
= Time dial, reset
E
T
n
FST
E
T
/FST
= Elapsed time
= Curve exponent (0.5, 1, 2)
= Full scale trip time (T
T
)
= Fraction of total travel toward trip that integration had
progressed to. (After a trip, this value will be equal to one.)
When the measured V/Hz rises above a pickup threshold, the pickup element becomes TRUE and an
integrating or definite time timer starts. If the V/Hz remains above the pickup threshold and the integration
continues for the required time interval as defined by the equations shown above and the set time dial,
the trip output becomes TRUE. But if the measured V/Hz condition falls below the pickup setting and
integrating reset is chosen, the integrating trip timer will ramp down towards reset at a linear rate based
on the reset time dial setting. See Appendix B,
Overexcitation (24) Inverse Time Curves
, for details on
each of the available time curves.
If the target is enabled for the 24 element, the target reporting function will record a target when the trip
output is TRUE and the fault recording function trip logic expression is TRUE. See Section 6,
Reporting
and Alarm Functions, Fault Reporting
, for more information about target reporting.
BESTlogic Settings for Volts Per Hertz Overexcitation
BESTlogic settings are made from the
BESTlogic Function Element
screen in BESTCOMS. Figure 4-31
illustrates the BESTCOMS screen used to select BESTlogic settings for the Overexcitation (24) element.
To open the
BESTlogic Function Element
screen for
Overexcitation (24),
select
Voltage Protection
from
the
Screens
pull-down menu and select the
24
tab. Then, select the
BESTlogic
button. Alternately,
settings may be made using SL-24 ASCII command.
Figure 4-31. BESTlogic Function Element Screen, 24
9365200990 Rev F
BE1-CDS240 Protection and Control
4-37
Summary of Contents for BE1-CDS240
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Page 38: ...1 28 BE1 CDS240 General Information 9365200990 Rev F This page intentionally left blank ...
Page 40: ...ii BE1 CDS240 Quick Start 9365200990 Rev F This page intentionally left blank ...
Page 152: ...ii BE1 CDS240 Metering 9365200990 Rev F This page intentionally left blank ...
Page 226: ...iv BE1 CDS240 Application 9365200990 Rev F This page intentionally left blank ...
Page 286: ...ii BE1 CDS240 Security 9365200990 Rev F This page intentionally left blank ...
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Page 292: ...ii BE1 CDS240 Human Machine Interface 9365200990 Rev F This page intentionally left blank ...
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Page 308: ...ii BE1 CDS240 ASCII Command Interface 9365200990 Rev F This page intentionally left blank ...
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Page 349: ...Figure 12 5 Horizontal Rack Mount Front View 9365200990 Rev F BE1 CDS240 Installation 12 5 ...
Page 361: ...Figure 12 17 Typical DC Connection Diagrams 9365200990 Rev F BE1 CDS240 Installation 12 17 ...
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Page 544: ...ii BE1 CDS240 Terminal Communication 9365200990 Rev F This page intentionally left blank ...
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