Basler Electric DECS-400 - Manual (Page 56)

44 9369700990 Rev R
Stator Current Limiter
The stator current limiter (SCL) monitors the level of stator current and limits it to prevent stator
overheating. The SCL operates in all modes except FCR. When operating in FCR mode, the DECS-400
announces a stator overcurrent condition but does not act to limit the stator current.
Stator current limiting is provided at two levels (Figure 11).
High-level stator current limiting is controlled by the High SCL Level and High SCL Time settings. When
the stator current increases above the High SCL Level setting, the DECS-400 acts to limit the level of
stator current. After the High SCL Time setting expires, the DECS-400 acts to limit the level of stator
current to the Low SCL Level setting value. The High SCL Level setting has a setting range of 0 to 66,000
Aac with 0.1 Aac increments. The High SCL Time setting has a setting range of 0 to 240 seconds with 0.1
second increments.
Figure 11. Stator Current Limiting
Low-level stator current limiting is controlled by the Low SCL Level setting, which serves as an
annunciation that the stator current is at an elevated level. The generator is permitted to operate
indefinitely at the low SCL level. The Low SCL Level setting range is identical to that of the High SCL
Level setting range.
The SCL will not respond until the SCL Initial Delay setting has expired.
Overexcitation Limiter
The overexcitation limiter (OEL) monitors the level of field current supplied by the static exciter and limits
the current to prevent field overheating. The OEL operates in all modes. Through user-configurable logic,
the OEL can be disabled only when the DECS-400 is operating in FCR mode. The DECS-400 will
announce an overexcitation condition but does not act to limit the excitation level.
There are two styles of overexcitation limiting available in the DECS-400: summing point and takeover.
Summing Point OEL
There are two sets of summing point OEL settings for off-line operation: a high-level setting and a low-
level setting. Figure 12 illustrates the relationship of the high-level and low-level setting. The high-level,
off-line OEL threshold is determined by the Off-Line High Level and Off-Line High Time settings. When
the excitation level exceeds the High Level setting, the DECS-400 acts to limit the excitation. After the
duration of the High Time setting expires, the DECS-400 acts to limit the excitation to the Low level
setting. The Off-Line High Level setting has a setting range of 0 to 11,999 Adc with 0.01 Adc increments.
The Off-Line High Time setting has a setting range of 0 to 10 seconds with 1 second increments. The low-
level OEL threshold is determined by the Off-Line Low Level setting, which serves as an annunciation that
off-line excitation is at an elevated level. The generator is permitted to operate indefinitely at the Off-Line
Low Level setting. The Off-Line Low Level setting has a setting range of 0 to 11,999 Adc with 0.1 Adc
increments.
TIME IN SECONDS
High
Current
Time
Continuous
P0013-19
11-10-04
0-60 s
Low
Current
Level
0-66,000 Aac
High
Current
Level
0-66,000 Aac
S
T
A
T
O
R CURRE
NT
Functional Description DECS-400