Industrial SX440 Automatic Voltage Regulator

The SX440 Automatic Voltage Regulator from Stamford is a panel-mounted AVR designed for brushless generator systems to automatically regulate alternator output by controlling the exciter field current. Widely used in diesel and gas generator sets, it maintains stable voltage during changing load and engine speed, and is compatible with Stamford alternators and compatible brushless generators. Key specifications include input 190–270 VAC and sensing input 190–270 VAC single phase, with an output up to 95 VDC and operation at 50/60 Hz, delivering voltage regulation accuracy of ±1.0%. It uses self-excited/shunt excitation and requires 4 A continuous excitation current (6 A intermittent for 10 seconds), plus ±10% external voltage adjustment via a 1 kΩ potentiometer. Features include overexcitation protection, EMI suppression, adjustable stability, a built-in soft start ramp, and under-speed protection with adjustable frequency roll-off. The device is panel-mounted for straightforward integration in diesel and gas generator control panels, supports an operating temperature range from -40°C to +70°C, and is available as an active replacement component through OEM and aftermarket suppliers; common replacements include Stamford SX440, MX341, and AS440.