[Boatanchors] [ARC5] No-load current of dynamotors?

[Charles]

Not a transistor to be found, and even the diodes are selenium... the 
transistor had just been invented in 1948 and this inverter is nearly 
that old :)

I should have mentioned, it's not a dynamotor (common field poles) but 
actually a motor-generator, if that matters to the unloaded motor current...


On 3/11/22 21:02, J Mcvey wrote:
> Does that inverter use germanium transistors by any chance?
>
> On Friday, March 11, 2022, 09:21:15 PM EST, Charles via ARC5 
> <arc5 at mailman.qth.net> wrote:
>
>
> Just wondering if anyone has measurements on the no-load input current
> of their dynamotors (of various sizes).
>
> My Bendix 2 KVA aircraft inverter is rated at 115 amp full-load draw,
> per the nameplate. Now that I have a monster unregulated 24-28 volt
> supply, I have measured the idling current at 26V at 40 amps. 1/3 of the
> full-load current seems kind of high? I was expecting more like 10-20%.
>
> The only 120 volt resistive load I had on hand was a 525 watt heat gun
> element, and the output voltage dropped only a few tenths of a volt,
> while the input current rose to 75 amps. Next data point will be a 900
> watt electric heater (the inverter is rated for 1 KVA single-phase),
> unless I rig up a three-phase load.
>
> (The only other dynamotors I have are small ones for "ARC-5" receivers
> and I haven't checked them yet).
>
> It does have two carbon-pile regulators, the original selenium
> rectifiers, and a couple of relays that draw a little here and there,
> but nothing's getting significantly warm except the air coming out of
> the rotating assembly (it has fans on each end cap that draw in, and
> exhausts from the middle). I can only assume that this is normal
> behavior? Thoughts?
>
> Cross-posted to Boatanchors and ARC-5 lists.
>
>
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