Automatic Voltage Regulation

[stephend]

My Volvox generator rated at 5kW has an AVR fitted.  Without any load the output voltage is 231V, with a 1.5kW motor load, the voltage reads 224V.  That's a 3% difference with only a 30% load.  A brief google for AVRs shows that most of them only vary the output voltage by 1%.  Given that I've had a number of other problems with this generator, how would I know if the AVR is broken?

[Alan]

The voltage regulation depends on how good the mechanical speed regulation is. The older design of diesel alternator had a lot more mass in the way of  larger flywheels, they could cope with direct on line motor starting much better. They could achieve better speed regulation. My 5 K.W. alternator is no better than 3%

Regards

Alan

[oliver90owner]

Is this stator or armature wound for output current? Rolled steel magnet frame for generator, or lightweight construction?  Electronic AVR or current transformer? How does the Hz vary over this range?  What is the droop at full load?  Belts tight and not slipping?   This is droop rather than variation?  Is the voltage stable at that particular setting?  What are your expectations?  What are you trying to run with it?  What is the power factor for that motor and is the motor load varying?  Is your generator output really 5kW, or is it 5kVA?  Is that a continuous output or the advertising absolute maximum (with time limitation in small print)?  Is the whole system rated at 5kW, or just the generator? 

All these things can make a difference as to how the perceived control effectiveness is functioning.  You may be comparing apples with oranges and need to study the small print if there is any.

only vary the output voltage by 1%  do you mean they control within 1% or are only able to change the (otherwise uncontrolled) voltage by up to 1%?

Regards, RAB

[knighty]

I....*think*...

you should check the frequency of the output unloaded/loaded....

the frequency should be directly proportional to the speed the generator is spinning.... no matter that output...

if there's more than a couple of hz movement up or down then it's a speed control problem... not a problem with the avr ?

[stephend]

Thanks for the replies all.  I went back to check the voltage under different loads, and the voltage was stable, between 229V and 231V from between 1A and 16A loads.  Realised that the voltage reading on the generator control panel isn't all that accurate  using a multimeter it was stable, now where's the sheepish grin icon when you need it?