Automatic Voltage Regulator (AVR) compatible with Leroy Somer R250

With two-line sensing, ADVR-250 is a hybrid analog-digital AVR for self-excited (shunt) generators. It’s compatible with Leroy Somer* R250 and can also replace R230. The innovative heat sink design significantly improves the heat radiation efficiency.

140.0 (L) x 81.0 (W) x 46.0 (H) mm

300 g +/-2%



Compact size, robust and high reliability

Innovative heat sink significantly increases cooling efficiency

Load Acceptance Module (LAM) protection

Soft start voltage ramping

Over excitation protection

Digital low frequency protection circuit, prevents thermal drift

EMI suppression

Built-in high capacity fuse


Sensing & Power Input (Average Reading)
Voltage 85 to 140 Vac 1 phase 2 wire
Frequency 50/60 Hz (Potentiometer setting)

Excitation Output
63 Vdc @ 120 Vac single phase
continuous 5A Max. 110 Vdc 5A for 10 seconds

Excitation Resistance
Min. 18 ohms
Max. 100 ohms

Fuse Spec.
Slow blow 5 x 20 mm 8A

External Volts Adjustment
+/-14% with 1 kΩ 1 watt trimmer

Build Up Voltage
Residual volts at power input terminal > 5 Vac 25 Hz

Soft Start Ramp Time
3 seconds +/-10%

Volts Regulation
Less than +/-0.5% (with 4% engine governing)

Response Time
Less than 20 ms

Static Power Dissipation
Max. 4 watts

EMI Suppression
Internal electromagnetic interference filtering

Under Frequency Protection (Factory Setting)
50 Hz system presets knee point at 48 Hz
60 Hz system presets knee point at 58 Hz

Over Excitation Current Limiting
Excitation Current 5A +/-10%

Voltage Thermal Drift
Less than 3% at -40 to +70 °C

Under Frequency Knee Point Thermal Drift
Less than +/-0.1 Hz at -40 to +70 °C

Operating Temperature
-40 to +70 °C

Storage Temperature
-40 to +85 °C

Relative Humidity
Max. 95%

5.5 Gs @ 60 Hz