R449 AVR for Leroy Somer generator
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R449 AVR is used on LEROY SOMER LSA 50.1 and LSA 51.2 alternators with AREP or PMG excitation.
With AREP excitation, the R 449 electronic AVR is powered by two auxiliary windings which are independent of the voltage detection circuit. The first winding (X1, X2) has a voltage proportional to that of the alternator (Shunt
characteristic) , the second (Z1, Z2) has a voltage proportional to the stator current (compound characteristic: Booster effect) . The power supply voltage is rectified and filtered before being used by the AVR monitoring transistor. As a result, the machine has a short-circuit current capacity of 3 IN for 10 s and good immunity to distortions generated by the load.
With PMG excitation, a permanent magnet generator (PMG) is added to the alternator. This is fitted at the rear of the machine and connected to the R 449 AVR. The PMG supplies the AVR with voltage which is independent of the main alternator winding. As a result, the machine has a short-circuit current capacity of 3 IN for 10 s and good immunity to distortions generated by the load.
The AVR monitors and corrects the alternator output voltage by adjusting the excitation current. The exciter field is fitted with permanent magnets in series (PMI system) which provide constant remanent voltage.