60
9440300990 Rev J
Limiters
DECS-250
Figure 46. Inverse Time Characteristic for Takeover OEL
Primary and secondary setting groups provide additional control for two distinct machine operating
conditions. Each mode of takeover OEL operation (offline and online) has a low-level
A
, high-level
B
, and
time dial
C
setting.
Once the field current decreases below the dropout level (95% of pickup), the function is reset based on
the selected reset method
D
. The available reset methods are inverse, integrating, and instantaneous.
Using the inverse method, the OEL is reset based on time versus multiple of pickup (MOP). The lower the
field current level, the less time is required for reset. Inverse reset uses the following curve (Equation 12)
to calculate maximum reset time.
𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇
𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟
=
𝑅𝑅𝐶𝐶
×
𝑇𝑇𝑇𝑇
(
𝑀𝑀𝑀𝑀𝑀𝑀
𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟
)
2
−
1
Equation 12. Inverse Reset Time Characteristic
Where:
Time
reset
= maximum time to reset in seconds
RC
= reset coefficient setting
E
<0.01, 100>
TD
= time dial setting <0.1, 20>
MOP
reset
= multiple of pickup <1.03, 205>
For the integrating reset method, the reset time is equal to the pickup time. In other words, the amount of
time spent above the low level threshold is the amount of time required to reset.
Instantaneous reset has no intentional time delay.
In BESTCOMS
Plus
®
,
a plot of the takeover OEL setting curves is displayed. Settings enable selection of
the displayed curves. The plot can display the primary or secondary setting curves, the offline or online
settings curves, and the pick up or reset settings curves.
Содержание DECS-250
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Страница 6: ...iv 9440300990 Rev J Revision History DECS 250 ...
Страница 16: ...xiv 9440300990 Rev J Contents DECS 250 ...
Страница 20: ...4 9440300990 Rev J Introduction DECS 250 ...
Страница 28: ...12 9440300990 Rev J Power Stage DECS 250 ...
Страница 32: ...16 9440300990 Rev J Voltage and Current Sensing DECS 250 ...
Страница 40: ...24 9440300990 Rev J Synchronizer DECS 250 ...
Страница 52: ...36 9440300990 Rev J Auxiliary Control DECS 250 ...
Страница 56: ...40 9440300990 Rev J Contact Inputs and Outputs DECS 250 ...
Страница 84: ...68 9440300990 Rev J Limiters DECS 250 ...
Страница 108: ...92 9440300990 Rev J Power System Stabilizer DECS 250 Figure 85 PSS Function Blocks and Software Switches ...
Страница 114: ...98 9440300990 Rev J Power System Stabilizer DECS 250 Figure 96 PSS Parameter Settings ...
Страница 124: ...108 9440300990 Rev J Stability Tuning DECS 250 ...
Страница 126: ...110 9440300990 Rev J Mounting DECS 250 Figure 103 Overall and Projection Mounting Dimensions ...
Страница 127: ...9440300990 Rev J 111 DECS 250 Mounting Figure 104 DECS 250 Escutcheon Plate Dimensions ...
Страница 128: ...112 9440300990 Rev J Mounting DECS 250 Figure 105 Panel Cutting and Drilling Dimensions for DECS 250 Panel Mounting ...
Страница 198: ...182 9440300990 Rev J Timekeeping DECS 250 ...
Страница 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
Страница 304: ...288 9440300990 Rev J Maintenance DECS 250 ...
Страница 316: ...300 9440300990 Rev J Specifications DECS 250 ...
Страница 334: ...318 9440300990 Rev J Analog Expansion Module DECS 250 ...
Страница 341: ...9440300990 Rev J 325 DECS 250 Contact Expansion Module Figure 188 CEM 2020 Input Contact and Output Contact Terminals ...
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