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uknown power transformer - radar-


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#1 madhatter1036

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Posted 06 November 2013 - 03:45 AM

I've acquired a power transformer for a radar/sonar A/N use. The tag with it only refer to military internal codes, nothing that can help sort the specifics. So I've done some pre-lim testing and here's what I canbest figure, it's more than likely a 3 phase unit, but i'm not 100% sure on that.

 

the side plug if you will has 6 bent wire terminal ends, it's about 10lbs and 4x6x4 inches in size fully potted and steel cased.

 

terminals 1,2 & 3 all have the same resistance between each, no internal connection to terminals 4,5 & 6 also which have the same resistance between them. in other words no two are different.

 

1,2 & 3 = 0.6 ohm

4,5 & 6 = 9.5 ohm

 

not having a 3 phase a/c source I'm left with using single phase on the primary side, I'll assume the primary is 0.6 ohms

 

using a mere 3 volts A/C here's the results

 

Input: Pins 4 & 6

Output:

1&3 = 10vac

1&2 = 16vac

2&3 = 6vac

 

Input: Pins 5 & 6

Output:

1&3 = 10vac

1&2 = 6vac

2&3 = 16vac

 

Input: Pins 4 & 5

Output:

1&3 = 0.5vac

1&2 = 13vac

2&3 = 13vac

 

Then using the  same 3vac measure the delta from the unpowered lead to opposite:

Input: Pins 4 & 6 = 3vac

Delta: Pins 4 & 5 = 2.5vac

Delta: Pins 5 & 6 = 0.5vac

 

Input: Pins 4 & 5 = 3vac

Delta: Pins 4 & 6 = 1.5vac

Delta: Pins 5 & 6 = 1.5vac

 

Input: Pins 5 & 6 = 3vac

Delta: Pins 4 & 5 = 2.5vac

Delta: Pins 4 & 6 = 0.5vac

 

I'm scratching my head here, it's almost like a buck/boost transformer. the voltages work out using the [LaTeX Error: One or more directories do not exist] factor

 


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#2 G4ΓΓ3ττ

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Posted 06 November 2013 - 04:22 AM

The turns ratio appears to be 1 to 5.3. So if it were a 120v 3p input you would get around 640V 3p out, and double that for 240 3p input. It seems delta wound on both sides from looking at your measurements.

 

How low of impedance was you AC source? The turns ratio may be a little different when more current flows through the windings, as the core may have only been operating around the initial permeability portion of the curve. But it seems like the AC supply you used didn't sag too much when you connected the transformer, so source impedance doesn't seem to be an issue.


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#3 madhatter1036

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Posted 06 November 2013 - 06:39 AM

the supply source is a spare heater transformer 2.5@10amp, unloaded it idles around 3vac, the power transformer didn't phase it at all. then again I wasn't loading the power transformer. The odd leg has me thinking it's a Y-D as that is supposedly the more  commen for step up units. a 3phase would step up 120 to 1100 with a 5.3:1 as it is also multiplied by 1.73.


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