[ARC5] No-load current of dynamotors?

[Ken]

I would be very, very, VERY suspicious of any selenium-anything by this late date!!!!Ken W7EKBSent via the Samsung Galaxy S21 5G, an AT&T 5G smartphone
-------- Original message --------From: Charles via ARC5 <arc5 at mailman.qth.net> Date: 3/11/22  19:07  (GMT-08:00) To: J Mcvey <ac2eu at yahoo.com>, BoatAnchors Digest <boatanchors at mailman.qth.net>, ARC-5 <arc5 at mailman.qth.net> Subject: Re: [ARC5] No-load current of dynamotors? 
    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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