Re: Alten A. van Kaick generator

eir Holmavatn schrieb:
Danke für das antwort ;-)

If I understand you correctly you advice me to just short terminals A
and D with an amperemeter and check the current flowing when the
generator gets up and running to 1500rpm under various loads.

Yes.

I think you plan to connect the generator to an isolated load (e.g. on a
ship), not to a power grid with other generators, don't you? My musings
below apply to this setup. In the previous posting, I thought about the
power grid setup, when both resistors don't have influence to the output
voltage... Just forget it if you don't have such a setup.

The purpose of both resitors is output voltage control: The A..D resitor
controls the off-load voltage. The J' resistor controls the voltage shift
under electrical(!) load.


As the induction voltage is controlled by the exciting current, you can
control the off-load voltage with the A..D resistor. The lower the
resistance, the higher the off-load voltage.
Set it up so you get ~230V when the machine is at 1500rpm. If you aren't
fixed to 50Hz, you may choose the A..D resistor value == 0 and change the
engine speed instead.


The current in the J' line is conntrolled by the generator main current (See
the datasheet without the regulator) and the J' resistor. This, too, is a
part of the exciting current. Higher than zero main current through the
generator will let the voltage at it's main terminals drop. With the
resistor in J' line, you can control the load-depending exciting current
and such, the compensating voltage.
Set it up that way the output voltage is roughly the same under load and
without it. If the shift doesn't matter, choose the J' resitor value == 0.


If you choose the both the resitors values == 0, you get the highest
possible torque the machine accepts. This is

M=P/(2pi*n)=12kW/(2pi*25/s)=76Nm (for *both* A..D and J' resistor == 0 Ohm)

The drawback of this "high" torque (and current) is the the high voltage
shift under load. So you may want to make the J' resistor R>0. You may do
this but remember the resitors are limiting the minimum exciting current of
the generator. If the resistance of both this and the J' line resistor
value is *too high* for the torque you apply to the generator, the
generator will go out of sync ("topple") and therefore, your machines may
be damaged.

The safe value for both resistors is ZERO.


Does this mean that the voltage regulation problably will work fine at
230 V even when the above terminals are shorted?

The voltage regulation with fixed rpm and changing torque should work
fine "within reasonable bounds", see above. So if your diesel(?) engine is
regulated to run at fixed speed (even if the torque changes!), and all you
change is the electrical current, the voltage regulation should work fine.

There will be no voltage regulation if the speed of your engine changes,
however.


By inserting a suitable resistor the generator's maximum current will be
kind of 'limited' to avoid damage under heavy load.

No. The maximum current you may get from the generator is only limited by
the torque you apply to it and heat the generator can dissipate.


BTW: Opening the A..D and/or J' connection under nominal load will indeed
make the generator topple. The generator torque will instantly go to a too
low value for the torque applied by the external machine and so, this
diesel(?) engine will radiply go n->oo. That may damage both.


Kind regards

Jan
.

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