Automatic Voltage Regulator for LSA alternators


The R438 automatic voltage regulator (AVR) for the Leroy-Somer LSA series of industrial alternators provides excitation current up to 4 A with excellent reliability for AREP & PMG excitation types. 

The R438 includes advanced protections such as over-excitation limitation and voltage sensing loss, and also features voltage droop for genset parallel operation. A Load Acceptance Module (LAM) is also included to handle load impact events.


Key specifications

 Technology  Analog
 Excitation mode AREP, PMG
 Rated excitation current  4 A
 Regulation accuracy (+/- %) 0.5 %
 Frequency range 10 – 100 Hz
 Voltage setting range (+/- %) 5 %
 kU/F limitation K = 1
 Loss of sensing voltage
 Over-excitation limitation
 Short circuit current limitation -
 Voltage droop
 Parallel operation between alternators
 Load Acceptance Module (LAM)


Compatible products


  • R726 module for Cos Phi regulation
  • R729 for Cos Phi + kVAr regulation & 4-20 mA signal treatment
  • External potentiometer
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