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Genuine Leroy Somer AVR - Automatic Voltage Regulator - Made in France

Key Features

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.

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

  • LSA 40
  • LSA 42.3
  • LSA 44.3
  • TAL 40
  • TAL 42
  • TAL 44 (for 12 lead operation)


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