Leroy Somer LSA 49.1 4P Manuel D'utilisation Et D'entretien page 31

LEROY-SOMER
PMG excitation
R 448
X2
Z1
X1
Z2
E+
E -
WARNING
For operation using the PMG system, the AVR ST9
jumper must always be disconnected.
2.3.3 - Frequency compared with voltage
(without LAM)
Voltage
Bend
U/U 48 Hz
N
100 %
50 Hz
2.3.4 - LAM characteristics
The LAM system is integrated in the R448 AVR as standard.
It can be reactivated by closing ST5.
- Role of the "LAM" (Load Adjustment Module) :
On application of a load, the rotation speed of the generator
set decreases. When it passes below the preset frequency
threshold, the "LAM" causes the voltage to drop by
approximately 15% and consequently the amount of active
load applied is reduced by approximately 25%, until the
speed reaches its rated value again.
Hence the "LAM" can be used either to reduce the speed
variation (frequency) and its duration for a given applied load,
or to increase the applied load possible for the same speed
variation (turbo-charged engines).
To avoid voltage oscillations, the trip threshold for the "LAM"
function should be set approximately 2 Hz below the lowest
frequency in steady state.
Voltage
ST5 disconnected
U
N
U/f
0.85 U
N
0
ST3
INSTALLATION AND MAINTENANCE
LSA 49.1 4P
ALTERNATORS
TECHNICAL CHARACTERISTICS
14
15
PMG
16
5 +
6 -
Exciter field
57.5 Hz
60 Hz
Frequency
Hz
50 Hz 60 Hz
Underspeed and LAM
Voltage
P2
LAM
- P4 trip threshold
for LAM or U/F
P4
(factory preset).
48 or 57.5 Hz
50 or 60 Hz
fC fN
Voltage
Transient voltage drop
U
N
0.9
0.8
LAM
Frequency
Max speed drop
f
N
0.9
0.8
Power
Load shedding due to "LAM"
1 s
0
Typical effects of the "LAM" with a diesel engine -
with LAM
2.3.5 - R 448 AVR options
- Current transformer for parallel operation of
....../1 A - 2.5 VA CL 1 (See the diagram included with this
manual).
- Remote voltage adjustment potentiometer :
470 Ω , 0.5 W min : adjustment range ± 5% (range limited by
internal voltage potentiometer P2). Remove ST4 to connect
the potentiometer. (A 1 k Ω potentiometer can also be used to
extend the adjustment range).
- R 731 module : detection of 3-phase voltage 200 to 500V,
compatible with parallel operation. Disconnect ST1 to
connect the module; set the voltage via the module
potentiometer.
- R 726 module : regulation system changed to "4-function".
(See the maintenance manual and connection diagram.)
• PF regulation (2F)
• voltage matching before paralleling (3 F)
• mains connection of alternators already running in parallel
(4F)
Ref. 3007 GB - 4.33/a - 10.00
(U/f)
LAM
LAM
Variation in the load
Time
(s)
2 s 3 s
without LAM (U/F only)
7