How is voltage regulated in Home Standby Generators (HSBs)?

Generac home standby generators regulate output voltage to help maintain approximately 120/240 VAC (depending on the installation) as electrical loads change. The way voltage is regulated depends on the generator model and alternator design.

What is an AVR?

AVR stands for Automatic Voltage Regulator.

• In brushed units, the AVR function senses output voltage and regulates it by controlling DC current to the rotor through the brushes. Increasing rotor magnetism raises output voltage when needed.
• In brushless alternators, voltage regulation is typically handled using different components (commonly a capacitor-based approach) and does not use brushes to deliver DC current to the rotor.

2010 and newer HSB voltage regulation

Most 2010 and newer Generac home standby generators regulate voltage through the generator controller (the controller performs the voltage regulation function rather than a separate, service-replaceable AVR module). PowerPact models are the primary exception.

Important: Generac home standby generators from 2010 and newer are brushed units.

Do I need to replace the AVR?

In most cases, you will not need (and should not plan) to replace an AVR on a 2010 and newer HSB because voltage regulation is handled at the controller (except PowerPact). If you are experiencing low voltage, high voltage, or unstable voltage, another issue is often the cause (for example, wiring and connection concerns, load-related issues, or a problem within the generator system that requires diagnosis).

If you believe your generator has a voltage regulation problem, contact an Independent Authorized Service Dealer (IASD) using the dealer locator.