So if you're measuring 1uH (ish) and the correct value is 100uH (ish)
thats a mutual coupling, M , of 0.99. Not bad.
Wonder if 250 MVA 400kV 3 phase supergrid transformers have a better M value.
Andy
On 4 April 2011 19:45, Warren Ziegler <[email protected]> wrote:
> Mike,
>
> I just measured a known good Decca output transformer with a Peak
> Atlas LCR meter.
> The 3.2mH is correct for the monitor winding, the other windings
> should be a bit above 106uH each (I got values between 106.4 and 106.8
> uH)
> --
> 73 Warren K2ORS
> WD2XGJ
> WD2XSH/23
> WE2XEB/2
> WE2XGR/1
>
>
>
> On Mon, Apr 4, 2011 at 2:34 PM, Mike Dennison
> <[email protected]> wrote:
>> Thanks for the suggestion Andy. I did that already using an Atlas LCR
>> meter
>> (one of the best bits of test gear I ever bought), but didn't believe
>> the result.
>>
>> It showed what looked to me like very low inductance, some 1.3uH on
>> the
>> 'primaries' and 3.2uH on the secondary. The 'monitor' winding is
>> much higher
>> than this. Would a single shorted turn make all of the inductances
>> low?
>> The Atlas declined to measure the DC resistances as they were too
>> low.
>>
>> Mike
>> ====
>>
>>> Disconnect all windings and measure the inductance. If the
>>> transformer is OK, the L will be high - with Xl many times the
>>> operating impedance. A shorted turn - which is what it looks as if
>>> you may have - will drastically lower L to a value that should be
>>> evident
>>>
>>> Andy
>>> www.g4jnt.com
>>>
>>>
>>>
>>> On 4 April 2011 18:56, Mike Dennison <[email protected]>
>>> wrote: > I have a fault on my Decca 5501 LF transmitter. It appears
>>> that the > main output transformer / combiner is faulty. Each Tx
>>> module takes > current when connected to the transformer, even when
>>> the output is > disconnected. And there is no power out of the
>>> transformer. > > I have some questions: > > According to the the
>>> circuit diagram, the transformer's output > winding has a 3.3nF
>>> capacitor across it. However, it seems to be > invisible! Does anyone
>>> know where it is? Is it inside the pot core? > > Does anyone have a
>>> spare transformer for sale? > > Has anyone had a similar fault? > > Is
>>> it difficult to disassemble the transformer? > > It is very difficult
>>> to test for shorted turns because the resistance > is extremely low. >
>>> > Any ideas? > > Mike, G3XDV > ========== > > >
>>>
>>
>>
>>
>>
>
>
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