Talking about my generation

[topchippyles]

48 minutes ago, Rough Hewn said:

A 5kva will only give out 2-3kw unless you want to melt it.
A 10kva genny is a bout 1-2k on eBay.
Or...
I've mentioned this before,
My brother got the dynamo off a broken engined 10k genny and married it to a Ford Fiesta engine, on a trailer.
It's sweet

Can i ask how you you have calculated that soul ?? A lot of factors to consider when working this out. As a maximum output a 5kva will give 5000 watts which is why its called a 5 kva generator, As you mentioned it will run steady around 2.5 kva but will just increase power on demand which is why you ear the engine pick up when power load is increased. Good guide on 240v with a heavy start up is twice the power and on 3 phase its 3 times the power , Example is you have a 3 phase 2 kva it would need 6 kva depending which way its wired up. 240 tends to be less issues 

Edited April 3, 2020 by topchippyles

[Rough Hewn]

Can i ask how you you have calculated that soul ?? A lot of factors to consider when working this out. As a maximum output a 5kva will give 5000 watts which is why its called a 5 kva generator, As you mentioned it will run steady around 2.5 kva but will just increase power on demand which is why you ear the engine pick up when power load is increased. Good guide on 240v with a heavy start up is twice the power and on 3 phase its 3 times the power , Example is you have a 3 phase 2 kva it would need 6 kva depending which way its wired up. 240 tends to be less issues 

Because we melted 2 5kva's.
Need 4x5kva fir 10kw.
(Running sound systems in the early nineties.)
?????
Hire company wasn't happy.
[emoji106]

[topchippyles]

1 minute ago, Rough Hewn said:

Because we melted 2 5kva's.
Need 4x5kva fir 10kw.
(Running sound systems in the early nineties.)
?????
Hire company wasn't happy.

Slightly different circumstances now you NUTTER ? Can imagine you freaking out to northern SOUL - soul 

[Stere]

Or old skool raver?

 

[openspaceman]

2 hours ago, topchippyles said:

 A lot of factors to consider when working this out. As a maximum output a 5kva will give 5000 watts which is why its called a 5 kva generator,

Yes 5kW is the maximum a 5kVA genset will output but this is into a purely resistive load, when you run a motor aside from the inrush current ( well it's not really inrush but a higher current until the motor is spinning fast enough that the back EMF (Electro Motive Force)  reduces the current) the load is inductive because of the motor coils, this means the current lags the voltage  so that while instantaneously  the current  and voltage are out of phase the voltage must stay at ~230V  but the current must not exceed the current rating of 22 amps. This means if the power factor of the motor is 0.8 you are only able to supply it with 4kW.

 

These capacitor excited alternators are a weird black art to design but they are simple. This one seems to run at 3000RPM so it probably has a coil and diode  in the rotor wound to give a north and south pole when it is energised. This then creates a magnetic flux which passes the main output coil. In this instance the output is only 100V open circuit so for some reason the magnetic flux hasn't saturated and I suspect the diode in the rotor or more likely there is a temperature limiting device, like a thermistor has failed in the rotor circuit.

 

The rotor is energised by the exciter coil and capacitor, @the village idiot says he changed the capacitor and unless the rotor residual magnetism is sufficient to excite the output to 100V by itself  this circuit is okay.

[doobin]

8 hours ago, openspaceman said:

Yes 5kW is the maximum a 5kVA genset will output but this is into a purely resistive load, when you run a motor aside from the inrush current ( well it's not really inrush but a higher current until the motor is spinning fast enough that the back EMF (Electro Motive Force)  reduces the current) the load is inductive because of the motor coils, this means the current lags the voltage  so that while instantaneously  the current  and voltage are out of phase the voltage must stay at ~230V  but the current must not exceed the current rating of 22 amps. This means if the power factor of the motor is 0.8 you are only able to supply it with 4kW.

 

These capacitor excited alternators are a weird black art to design but they are simple. This one seems to run at 3000RPM so it probably has a coil and diode  in the rotor wound to give a north and south pole when it is energised. This then creates a magnetic flux which passes the main output coil. In this instance the output is only 100V open circuit so for some reason the magnetic flux hasn't saturated and I suspect the diode in the rotor or more likely there is a temperature limiting device, like a thermistor has failed in the rotor circuit.

 

The rotor is energised by the exciter coil and capacitor, @the village idiot says he changed the capacitor and unless the rotor residual magnetism is sufficient to excite the output to 100V by itself  this circuit is okay.

Yes but have you checked the flux capacitor?

[Dan Maynard]

One of my factory customers use a firm that repair electrical and electronic equipment, some of their gear is obsolete and sometimes it's faster to repair than buy new. I'll see if I can look them up.

Might have to ship it there but if it's that expensive then would be worth it.

Kontroltek.

Looking at their website probably not good for you, I reckon Les is spot on with rewind companies.

[Dan Maynard]

Is @gensetsteve still an active member, may be worth rattling his cage. @the village idiot    
its a bit cruel bringing a Genny down to a stall with log splitters, have you considered using  engine driven hydraulic power packs?
 
Bob

I thought maybe he puts the generator a long way away so he can still hear Radio 4 ?

Long extension leads don't help, I think because they reduce the voltage available at the motor during startup.

[openspaceman]

34 minutes ago, doobin said:

Yes but have you checked the flux capacitor?

No Scotty

[the village idiot]

10 hours ago, Dan Maynard said:

I thought maybe he puts the generator a long way away so he can still hear Radio 4 ?

Long extension leads don't help, I think because they reduce the voltage available at the motor during startup.

Yes, we like to have the generator a fair way from the splitters so hydraulic power packs are not ideal. It does mean that we probably have a voltage drop but we have not had any problems with the splitter motors.

 

I have contacted two windings companies. Neither of them wanted the job. One of them insisted that the alternator would be Chinese and not worth fixing even though I told him repeatedly that it isn't. It's a Mecc Alte (Italian).

 

If anyone knows of a windings company that actually does re-windings do let me know.