Leroy Somer AVR and Automatic Voltage Regulators
A Leroy Somer AVR keeps your generator's voltage steady when the load changes. It reads the output of the alternator and adjusts the current going to the exciter field, so lights, motors, and electronics get clean power. At General Power, we stock genuine Leroy Somer automatic voltage regulators for replacement, repair, and new builds. We also carry voltage regulators from other leading makers if you service a mixed fleet.
Matching a Leroy Somer AVR to Your Excitation System
The most important step before you buy is knowing how your alternator is excited. Each regulator is built for certain excitation types, and the wrong match can cause poor regulation or damage. Check the nameplate on your alternator and the label on your old regulator for these details:
- SHUNT excitation: The regulator draws its power from the alternator output. Models like the R250 and R220 are common choices for this setup.
- AREP excitation: Auxiliary windings feed the regulator, which helps the generator hold voltage during motor starts and short circuits.
- PMG excitation: A permanent magnet generator supplies the regulator with power that does not depend on the main output. The R448 works with both AREP and PMG systems.
- Frequency and sensing voltage: Confirm whether your set runs at 50 Hz or 60 Hz and what voltage the regulator needs to sense.
If any of these details are missing or worn off, send us the alternator model and serial number. We can also help you find the right Leroy Somer alternator if the whole unit needs to be replaced.
Analog and Digital Leroy Somer Automatic Voltage Regulators
Analog regulators are simple, proven, and easy to set with a few adjustment screws. They are a good fit for standby sets and single generators with steady loads. Many include underspeed protection, which lowers voltage when engine speed drops, and a load acceptance module (LAM) that helps the engine recover when a large load hits all at once.
Digital models give you finer control and more settings. The D350 is set up through software and suits many modern alternators. The D550 adds programmable functions for sets that run in parallel with other generators or with the utility grid. Digital regulators often pair with modern generator control panels for monitoring and protection.
Signs Your Voltage Regulator Needs Replacement
A failing regulator often shows clear symptoms before it stops working. Catching them early can protect your alternator windings and the equipment connected to your generator. Watch for these warning signs:
- Lights that flicker or dim while the engine runs at a steady speed
- Output voltage that climbs too high or sags too low
- Voltage that swings each time a load is added or removed
- No output voltage at all, even though the engine runs normally
These symptoms can also come from other parts, so test before you order. A bad rotating diode or a weak PMG can act like a failed regulator. We stock Leroy Somer diodes and other replacement alternator parts, so you can fix the true cause in one order.
Buying From General Power
General Power is a Miami, Florida based OEM, master distributor, and authorized dealer. Since 1999, we have served more than 10,000 customers in over 100 countries and hold an A+ rating from the BBB. Our sales specialists and engineers are individually certified by the Electrical Generating Systems Association.
Our bilingual staff offers same day quoting, same day shipping on stocked items, and after sales support. Alongside your regulator, you can order generator ends, transfer switches, or complete diesel generator sets. Contact us with your alternator details, and we will help you choose the right Leroy Somer AVR.
