What is a Stamford AS440 AVR?

The Stamford AS440 AVR is an analogue automatic voltage regulator, used on the Stamford AVK range of AC alternators. These alternators are coupled to many diesel engine brands worldwide to produce diesel generators.

The AVR on a diesel generator is used to maintain the voltage during steady state loads and transient conditions when load is applied or removed. You can read about the effect of applying load to the alternator.

What protections does the Stamford AS440 have built in?

The AS440 has "under frequency roll off" (UFRO) as standard. The AVR incorporates an under-speed protection circuit which gives a volts/Hz characteristic when the generator speed falls below a pre-set (adjustable) threshold known as the "knee" point.

Over-excitation also comes as standard on the AS440.  This prevents alternator damage if the pre-set maximum excitation levels of current are exceeded.

It also benefits from loss of sensing protection in the event of a problem with the sensing circuit.

Where can I get its technical specifications?

You can download the technical specifications of this AS440 AVR below.