generator avr?

[ghound]

I know little of electrics as it scares me sh1tless, but i need to know if my geny has an avr fitted.
Can you tell from the pics? It's a 4.1kva honda engine about 10 years old?

 

[piman]

Hello Ghounmd,

although not obvious, it is unlikely not to have one.

Why do you ask, is the voltage not constant, (there will be some very slight variation with load)?

Alec

 

[ghound]

I was wondering cos a plasma i have bought states that if your going to use a geny it needs to be fitted with an avr?

 

[piman]

Hello Ghound,

OK, as I say it's unlikely not to have one otherwise the more load the less voltage you'll get out which is not a lot of use.

Alec

 

[Robotstar5]

Try contacting Mecc Alte (UK) with serial/model number, I'm sure they'd know

 

[piman]

Hello The Snooper,

modern alternators have long since done away with slip rings. They are virtually all brushless.

Alec

 

[the snooper]

not the avr ones have a look at spares for all the chinese types

have a look here

they are just like car altenators they still use them

even on mec alte spa's web site single phase units are brushless with capacitor regulation
or brush with electronic regulation there are some that are brushless with an avr they will be expensive
but there are still more about then you would think


any way back to the op his definatley doesnt have an avr

here is the spec sheet for the alternator

 

[piman]

Hello The Snooper,

how can you have a useful alternator without some sort of voltage regulation, however basic. It just would be useless. The field has to vary with load or else the voltage will droop and continue to do so as the load increases?

Alec

 

[shenion]

They have regulation, it is just how good it works.

Most have a magnetized core with a winding around it. When the field reaches a pre-set level, the winding shorts the field out some via zener diode. Works well enough to run lights and motors.

A sudden change in load or power factor can collapse the field, it takes a while to build back up.

The AVR type would respond quicker as it can change the field quickly.

The one shown, if it has brushes probably has some sort of regulation.

 

[the snooper]

Hello The Snooper,

how can you have a useful alternator without some sort of voltage regulation, however basic. It just would be useless. The field has to vary with load or else the voltage will droop and continue to do so as the load increases?

Alec

the altenator shown will use engine speed to regluate the voltage 3000 rpm will produce 50hz frequency at a given voltage (240) and as you increase the load the govenor on the engine attempts to keep the rpm at a steady 3000.
any variaion of speed will produce higher or lower voltages but more importantly will change the frequency which will damage sensetive equipment ie electroinc gear

 

[piman]

Hello The Snooper,

you are mixing up two functions. Yes, the governor keeps the frequency constant and as load increases then more power is fed into the generator. The alternator field also needs regulating to keep the voltage constant, as the load varies.

Alec

 

[the snooper]

i suggest you either do some research or strip one down the parts in that altenator are
2 field coils
2 coils on the armature
2 diodes terminating the armature coils some have a varistor
and 1 capacitor

nothing else
the windings dictate what voltage is generated at a given speed
just like a battery just because you switch on more light doesnt mean the voltage drops
all an avr does is give you a more stable voltage ie when loads increase and decrease it stays level where as the conventional type fluctuates slightly

 

[piman]

Hello The Snooper,

it cannot be compared to a battery. The voltage depends on load and to compensate the field needs to be adjusted, an AVR regulates the voltage as the load varies. Without an AVR the voltage does not vary slightly at all, but significantly.

Alec