9440300990 Rev J
63
DECS-250
Limiters
E
Real Power Exponent:
Enter a value of 1 or 2.
F
Real Power Filter Time Constant:
Enter a value from 0 to 20 seconds in 0.1 second increments.
Stator Current Limiter
BESTCOMSPlus Navigation Path:
Settings Explorer, Operating Settings, Limiters, SCL
HMI Navigation Path:
Settings, Operating Settings, Limiters, SCL
The stator current limiter (SCL) monitors the level of stator current and limits it to prevent stator
overheating. To limit the stator current, the SCL modifies the excitation level according to the direction of
var flow into or out of the generator. Excessive stator current with leading power factor calls for increased
excitation. Excessive stator current with lagging power factor calls for reduced excitation.
The SCL can be enabled
A
in all regulation modes. When operating in Manual mode, the DECS-250 will
announce high stator current but will not act to limit it. Primary and secondary SCR setting groups provide
additional control for two distinct machine operating conditions. Stator current limiting is provided at two
levels: low and high (see Figure 50). SCL settings are illustrated in Figure 51.
Figure 50. Stator Current Limiting
Low-Level Limiting
When the stator current exceeds the low-level setting
B
, the DECS-250 annunciates the elevated level. If
this condition persists for the duration of the High SCL Time setting, the DECS-250 acts to limit the
current to the low-level SCL Setting. The generator is permitted to operate indefinitely at or below the low-
level threshold.
High-Level Limiting
When the stator current exceeds the high-level setting
C
, the DECS-250 acts to limit the current to the
high-level value. If this level of current persists for the duration of the high-level time setting
D
, the DECS-
250 acts to limit the current to the low-level SCL setting.
Initial Delay
In the case of low- or high-level stator current limiting, the limiting function will not respond until an initial
time delay
E
expires.
Содержание DECS-250
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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 ...
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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 ...
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Страница 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
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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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