Rewiring a Transformer

MisterBill2

Joined Jan 23, 2018
9,788
Conductors for a winding that are connected in parallel with each other are not going to increase the voltage output.
Have you done the turns/volt test?
It would appear that the 400v (~170v) winding could be connected in the auto transformer mode i.e. in series with the 240v supply. and the total equal to 400v?
I have suggested that several times. It might also be feeding a voltage doubler circuit, since the current required is only a little.
AND, here is an interesting thought. Since that winding was done with a much different kind of wire, possibly the transformer has been repaired once before.
I asked the TS to examine the circuit on the PCB to see if it might be a voltage doubler, I have not got a response back on that yet.
A voltage double provide twice the peak to peak voltage at no load current and light loads, so it would work very well for an insulation breakdown test supply.
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
I understand what you are saying,am going by what the Transformer manufacturer Trans-Sonic , is saying as follows:

"as per your request for the secondary winding voltages of the TT1418 Transformer is as follows.
Transformer outputs:
1st Sec 1.0 - 420v @ 3A
2nd Sec 2.0- 6v @32A
3rd Sec 3.0- 13v @ 400mA"

PS: am still working on a trace of the 400v onto the board .
Spike
edit: 1st Sec 1.0 - 420v@3mA
 
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MisterBill2

Joined Jan 23, 2018
9,788
The other two secondaries are delivering the correct voltages, per post #59 . As I look at the quoted specifications listed in post #82, it is very clear that the "400volt" secondary can not provide 3 amps at 420 volts, because not only is the wire not sized for 3 amps, but the power would be 1260 watts, far more than a transformer that size is able to deliver.
So I conclude that the current specification is WRONG, and if the current is wrong then probably the voltage would be wrong as well.
The credibility of the specification is lost at this point.
And we have not been told what the measured voltage on that secondary is, or have we? Now I realize that it is only wondering how 175 turns can provide 420 volts. I do not find any statement as to what voltage is actually measured on that secondary. So all commets are ended until we learn what the actual voltage is. My guess is about 420/9 volts, or close to that value.
 

MaxHeadRoom

Joined Jul 18, 2013
23,906
During my early training, I grew up with the old Hand crank Megger, two types, one for the measurement of low continuity, (ground) resistance etc, the other the high voltage, 500v - 1kv, for insulation check.
The latter does not usually require anything much in the way of current requirement.
The present hand held versions are portable and quite small, 'fits in the hand.' :cool:

1633986010348.png
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
The other two secondaries are delivering the correct voltages, per post #59 . As I look at the quoted specifications listed in post #82, it is very clear that the "400volt" secondary can not provide 3 amps at 420 volts, because not only is the wire not sized for 3 amps, but the power would be 1260 watts, far more than a transformer that size is able to deliver.
So I conclude that the current specification is WRONG, and if the current is wrong then probably the voltage would be wrong as well.
The credibility of the specification is lost at this point.
And we have not been told what the measured voltage on that secondary is, or have we? Now I realize that it is only wondering how 175 turns can provide 420 volts. I do not find any statement as to what voltage is actually measured on that secondary. So all commets are ended until we learn what the actual voltage is. My guess is about 420/9 volts, or close to that value.
Sorry my bad,
Transformer outputs should read :
Primary: 0 – 110 – 240 V

Secondary 1: 0 – 420 V @ 3 mA

Secondary 2: 0 – 6 V @ 32 A

Secondary 3: 0 – 13.2 V @ 400 mA

Yes I have given you what the voltages are in my last drawing #76 !
 

MisterBill2

Joined Jan 23, 2018
9,788
OK, now I see that it was additions to an attached drawing, not a list. And the value of 56 volts is not far off from 420/9, my thinking back in post #84. so the transformer has been rewound once by somebody who made that incorrect assumption that the 9 strand cable equalled separate turns. So if you can get quite a bit of thin wire you can correct the problem by removing that one winding and adding 9X170turns of thin wire. to deliver the needed 400 volts. But before you power that one up, add a small 1/8 watt 100 ohm resistor in series to act as a fuse to protect that very fine wire winding. And now you know that you were wise enough to ask about the wire before making the same mistake!
 

Thread Starter

spike1947

Joined Feb 4, 2016
383
OK, now I see that it was additions to an attached drawing, not a list. And the value of 56 volts is not far off from 420/9, my thinking back in post #84. so the transformer has been rewound once by somebody who made that incorrect assumption that the 9 strand cable equalled separate turns. So if you can get quite a bit of thin wire you can correct the problem by removing that one winding and adding 9X170turns of thin wire. to deliver the needed 400 volts. But before you power that one up, add a small 1/8 watt 100 ohm resistor in series to act as a fuse to protect that very fine wire winding. And now you know that you were wise enough to ask about the wire before making the same mistake!
Hi
Thanks for all your input into this conundrum for me, yes that would make sense and solve my problem, but , I am 99% sure that this Transformer has deff not been opened up/rewired !, but glad that you understand what I am on about ( that makes me feel better in mind )
Spike
 
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