Tags: Leroy Somer AVR R438 for LEROY SOMER Generator

LEROY SOMER AEM110RE003, AEM110RE017, 922-045

Description
LEROY SOMER R438 AVR FOR LEROY SOMER ALTERNATORS For both AREP amp; PMG excitation systems, the alternator voltage regulator is the R438.With AREP excitation, the R438 electronic AVR is powered by two auxiliary windings which are self-sufficient of the voltage match circuit. The first winding has a voltage in proportion to that of the alternator (characteristic Shunt), the second has a voltage in proportion to the stator current (compound characteristic: Booster effect).
The power supply voltage is rectified and filtered before being used by the AVR monitoring transistor. This principle ensures that regulation is not unnatural by distortions generated by the load. This excitation system consists of a "PMG" (permanent magnet generator). This is fitted at the rear of the machine and connected to the R438 AVR. The PMG supplies the AVR with constant voltage which is independent of the main alternator winding. As a result the mechanism has a short-circuit current capacity and good immunity to distortions generated by the load. The AVR monitors and corrects the alternator output voltage by adjusting the excitation current. - 50/60 Hz selection via the ST3 jumper.

The LAM system is integrated in the R 438 AVR as standard. Role of the "LAM" (Load Adjustment Module) On function 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 13% or 25% and
consequently the quantity of active load applied is reduced by approximately 25% to 50%, 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 one speed variation (turbo-charged engine). To avoid voltage oscillations, the trip threshold for the LAM function should be set approximately 2 Hz below the lowest frequency in solid state. During load impacts, the purpose helps the genset to return to its rated speed faster thanks to a gradual increase in voltage according to the principle:

General Characteristics
* Voltage regulation +/- 0.5 % at steady state and constant speed.
* Phase to phase voltage sensing.
* Control by transistor means the regulation quality is independant of load applied.
* Integrated "LAM" system to cope with increased loads applied to the engine
* Suitable for high levels of vibration and harsh environments.
* The R 438 is compatible with other modules giving additional functions.
* Standard power supply: AREP or PMG.
* Rated overload current: 8 A - 10 s
* Electronic protection (overload, shortcircuit on opening of voltage sensing circuitexcitation overload current for 10 seconds then return to approximately 1A.
* Fuse : F1 on X1, X2. 8A ; slow - 250V
* Voltage sensing : 5 VA isolated via transformer;
* 0-110 V terminals = 95 to 140 V,
* 0-220 V terminals = 170 to 260 V,
* 0-380 V terminals = 340 to 520 V.
* Voltage regulation ± 1%.
* Normal or rapid response time via ST2 jumper
* Voltage adjustment via potentiometer P2
* Current sensing (parallel operation): C.T. 2.5 VA cl1, secondary 1 A (optional).
* Quadrature droop adjustment via potentiometer P1
* Max. excitation current adjustment via P5