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.
Summary of Contents for DECS-250
Page 2: ......
Page 6: ...iv 9440300990 Rev J Revision History DECS 250 ...
Page 16: ...xiv 9440300990 Rev J Contents DECS 250 ...
Page 20: ...4 9440300990 Rev J Introduction DECS 250 ...
Page 28: ...12 9440300990 Rev J Power Stage DECS 250 ...
Page 32: ...16 9440300990 Rev J Voltage and Current Sensing DECS 250 ...
Page 40: ...24 9440300990 Rev J Synchronizer DECS 250 ...
Page 52: ...36 9440300990 Rev J Auxiliary Control DECS 250 ...
Page 56: ...40 9440300990 Rev J Contact Inputs and Outputs DECS 250 ...
Page 84: ...68 9440300990 Rev J Limiters DECS 250 ...
Page 114: ...98 9440300990 Rev J Power System Stabilizer DECS 250 Figure 96 PSS Parameter Settings ...
Page 124: ...108 9440300990 Rev J Stability Tuning DECS 250 ...
Page 126: ...110 9440300990 Rev J Mounting DECS 250 Figure 103 Overall and Projection Mounting Dimensions ...
Page 127: ...9440300990 Rev J 111 DECS 250 Mounting Figure 104 DECS 250 Escutcheon Plate Dimensions ...
Page 198: ...182 9440300990 Rev J Timekeeping DECS 250 ...
Page 210: ...194 9440300990 Rev J CAN Communication DECS 250 ...
Page 304: ...288 9440300990 Rev J Maintenance DECS 250 ...
Page 316: ...300 9440300990 Rev J Specifications DECS 250 ...
Page 334: ...318 9440300990 Rev J Analog Expansion Module DECS 250 ...
Page 351: ......
