SDMO R33C3, User And Maintenance Manual

Page: 235 / 244

LEROY-SOMER
7
2010.11 / f
Installation and maintenance
R438
A.V.R.
- LAM : action eliminated by cutting the ST5
jumper.
2.3.2 - Gradual voltage return function
During load impacts, the function helps the
genset to return to its rated speed faster
thanks to a gradual increase in voltage ac-
cording to the principle:
- If the speed drops between 46 and 50 Hz,
the rated voltage follows a fast gradient as it
is restored.
- If the speed drops below 46 Hz, since the
engine needs more help, the voltage follows
a slow gradient as it returns to the reference
value.
2.4 - Typical effects of the LAM with
a diesel engine with or without a
LAM (U/F only)
2.4.1 - Voltage
2.4.2 - Frequency
2.4.3 - Power
LAM
U
N
0
48 or 57.5 Hz
0.85 U
N
Voltage
U/f
50 or 60 Hz
fC fN
Voltage
ST5 disconnected
ST3
P2
Underspeed and LAM
0
Time
Drop N
≤
46 Hz
U
Drop N > 46 Hz
U
N
0
0,9
0,8
(U/f)
with
LAM
Time
without LAM
1 s 2 s 3 s
Transient voltage drop
0,9
0,8
f
N
Max speed drop
0
with
LAM
Time
without
LAM
1 s 2 s 3 s
0
1 s 2 s 3 s
Time
LAM
Variation in the load
Load on the shaft (kW)
Load shedding due to "LAM"
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