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Hi Ole, the transformer is designed for primary 230v according to the nameplate. With what voltage should I then measure the current? The transformers are also different in the saturation, although the transformers are identical, I think I have a video of it. Greetings Sven

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Von: "[email protected] [EVGRAY]" <[email protected]> 
Datum:26.01.2018  10:29  (GMT+01:00) 
An: [email protected] 
Betreff: Re: AW: Re: AW: Re: AW: Re: AW: Re: Aw: Re: AW: [EVGRAY] Re: Kone & Hector, you guys finally did it! 

Hi Sven,

That current is too much. There should be almost no current flowing. This is the full magnetizing current at no load  condition. This drives the transformer close to saturation. To make the transformer cheaper the no load magnetization is put closer to saturation to squeeze higher power density through the transformer. Perhaps the transformer is for 220 or 230V?!

Try the measurement at some less current to avoid saturation of the core. At 0.5A there will be 0.5V per Ohm of non-inductive voltage. This also influences the calculation. If using the winding as a choke it mustn't go into saturation as this prevents it from working as a choke. I.e. the inductance almost disappears when saturated and thus prevents the choke from storing any more energy.

Regards
Ole


---In [email protected], <s.friedrich@...> wrote :


Hello Ole, you have quite right volts divided by electricity. that's how I calculate it. The ohmic share I leave except because it is identical transformers unfortunately they do not behave the same. I have set several test voltages and can not get a common linearity. I can apply additional windings to the transformers but there are only partial successes. I have now tuned both transformers at 240 volts. It will flow at both transformers then 579- 582 mA. If I increase the voltage by 1 volt, the current increases massively, but just different for each transformer. I do not know how Hector wants to tune the coils because they always behave differently at different voltages. This 0.003 deviation I can only measure the current. An LCR meter that is so accurate I can probably not afford. Greetings Sven


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Von: "onielsen@... [EVGRAY]" 
Datum:26.01.2018 01:33 (GMT+01:00) 
An: [email protected] 
Betreff: Re: AW: Re: AW: Re: AW: Re: Aw: Re: AW: [EVGRAY] Re: Kone & Hector, you guys finally did it! 

 
Hi Sven,

I'm not sure I understand. The impedance is the voltage divided by the current. The inductive reactance is the imaginary part of the impedance where the current lags 90 degrees behind the voltage. If the current doesn't lag 90 degrees behind the voltage then there's also resistance in series with the coil.

If the series resistance is small compared to the inductive reactance the reactance can be calculated as the voltage divided by the current because the reactance becomes equal to the impedance when the resistance is decreased to zero. The phase angle Φ between the voltage and current will then increase to 90 degrees.

     
The figure is taken from here: https://www.electronics-tutorials.ws/accircuits/ac-inductance.html

As the inductive reactance is

Where f is the frequency and L the inductance the inductance then becomes:

Assuming low resistance compared to the reactance XL this latter almost becomes equal to the impedance Z. At high current the core of an inductor can saturate which decreases the inductance. Thus make the measurements at low current to avoid saturating the core. Perhaps this is what you're expiring. The phase angle between the voltage and current can be checked with a scope to be sure it is 90 degrees. Else this simple calculation doesn't apply and the resistance or the phase angle has to be known too for the correct calculation of the inductance.

Regards
Ole



---In [email protected], <s.friedrich@...> wrote :


Hello Ole, it is not accurate at 50Hz to measure the reactive current and to calculate the inductance over xl because these devices work anyway with 50 Hz and I work with this frequency in my experiments. The differences are extremely measured from 250 mH inductance to 1.12 H calculated inductance over xl. Greetings Sven


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Von: "onielsen@... [EVGRAY]" 
Datum:25.01.2018 13:09 (GMT+01:00) 
An: [email protected] 
Betreff: Re: AW: Re: AW: Re: Aw: Re: AW: [EVGRAY] Re: Kone & Hector, you guys finally did it! 

 
Hi Sven,

"My LCR meter shows completely different values ​​as the calculation over XL"
The calculation also has to take into account the resistance and capacitance. Some LCR meters can measure the device under test at different frequencies to change the influence of the parasitic parts of the device. E.g. like watching the influence of the capacitance and resistance of an inductor.

The parasitic parts of a coil can be found with a sine generator and an oscilloscope and some calculations. The inductance can be found as well.

Inductor model:

The image is taken from here: http://www.techlib.com/area_50/Readers/Craig/switching.htm
For explanation go the bottom chapter "Real World Inductors" on that page.

Regards
Ole



---In [email protected], <s.friedrich@...> wrote :



Hi Ole, Warren, I can not build the capacitors myself. Tuning the inductors is a challenge. I can still calculate the reactance when I put the transformer to 50 Hz 230v and measure the mA. Then Xl = U x I. If I bring both transformers to the same XL value I have the same inductance. My LCR meter shows completely different values ​​as the calculation over XL. Greetings Sven
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Von: "Warren Keillor schoonersolsticemoon@... [EVGRAY]" 
Datum:25.01.2018 01:29 (GMT+01:00) 
An: [email protected] 
Betreff: Re: AW: Re: Aw: Re: AW: [EVGRAY] Re: Kone & Hector, you guys finally did it! 

 
Sven

You change the uf value by simply taking scissors and trimming down the aluminium foil that is inside the plastic sheet. You can get very high tollerances as you discover this sloppy primitive method of making capacitors.
Other than being larger than commercial capacitors, they are very good at keeping the correct values through a very large voltage range.
Hot glue is good to stick the rolls tight against moisture. I use 3M clear tape for holding the roll rolled up tight, and temporarly placing parts. Super glue the electrodes in place.
Cheers
Sent from Yahoo Mail on Android

...

Hello Ole,

the differences between the voltages are very different as far as the current consumption is concerned. Actually, one should assume that the transformers should actually behave fairly evenly, at least linearly, the current should increase with increasing voltage. What I particularly noticed is that a transformer is a bit louder than the other or just has a different pitch.

How to tune a transformer so!?! I could imagine that it is synonymous s.der core but there I have no influence on it.

regards

Sven

Hi Sven,

At the voltage you did the measurement the inductance is low. For a proper designed transformer it should be designed to allow perhaps 10% over voltage before entering saturation. For a cheap transformer it may become too expensive when using proper design rules. When the transformer is loaded the secondary winding makes an opposite directed field that tends to cancel the field of the primary winding and thus drives the primary field away from saturation. The transformer then becomes a resistive load instead of the reactive load that it is when no current runs in the secondary winding.

For the inductance of the transformer working in the linear region the voltage has to be below where the current starts to increase. The measurement can be done at any voltage giving a low current in the transformer.

At 230V and 280mA the transformer has 64VA reactive power in it. Normally the measurement is done at some few volts when using a battery operated LCR meter. Try measuring at 200V or 100V or 24V to be sure no saturation occurs.

Regards
Ole


---In [email protected], <s.friedrich@...> wrote :

 

 Hi Ole, the transformer is designed for primary 230v according to the nameplate. With what voltage should I then measure the current? The transformers are also different in the saturation, although the transformers are identical, I think I have a video of it. Greetings Sven
 

 Von Samsung Mobile gesendet

 ...

Hi Sven,

My guess is that the transformers are made for being cheap. If made for microwave ovens they are only used intermittently at full power thus no problem. For continuous standby use they may be energy consumers if having too much resistance that dissipates the power as heat (active power) or Watts. If the power is pure reactive (VA-reactive) across only some few Ohms of resistance no problem too as very little heat dissipation takes place then. But it does look like some saturation is happening.

Regards
Ole
 

---In [email protected], <s.friedrich@...> wrote :

 Hello Ole,

the differences between the voltages are very different as far as the current consumption is concerned. Actually, one should assume that the transformers should actually behave fairly evenly, at least linearly, the current should increase with increasing voltage. What I particularly noticed is that a transformer is a bit louder than the other or just has a different pitch.

How to tune a transformer so!?! I could imagine that it is synonymous s.der core but there I have no influence on it.

regards

Sven

Empty body

Hi Sven,

When you say abused is the insulation all right? If a transformer has a short in a winding this heats the transformer and is seen as active load. Perhaps a scope reading of the voltage and current is needed to see if the load is active or reactive. At no load the voltage and current ought to be shifted by 90 degrees. If putting the readings in x-y mode the display should show a non-tilted ellipse for reactive power. Any tilt is caused by resistance and is active (real) power.

When active power is taken from a transformer the inductance of the primary is reduced by the canceling flux from the secondary.

Regards
Ole
 

---In [email protected], <s.friedrich@...> wrote :

 Hi Ole, I'm surprised that are transformers for 24V forklift chargers, these devices were not cheap. On the one transformer was a nameplate. The transformers are pulse-proof and can deliver 40A at 25.2 volts.
 
 What struck me then when I abused one as a choke that they were eventually warm.
 
 Too little iron for the large winding with large cross-section, I have to understand that!?!
 
 I still have a microwave transformer here, which really has a very bad degree of efficiency at 230 volts, which takes up no load 4390 mA and at 100 volts, the power consumption is twice as high as the other. On the microwave transformer stands for 1100VA although he is much smaller. I just noticed that the MOT has a small magnetic shunt, but does this have any advantages to work as a transformer except that it may not overload it so quickly.
 
 regards
 
 Sven   Gesendet: Freitag, 26. Januar 2018 um 18:58 Uhr
 Von: "onielsen@... [EVGRAY]" <[email protected]>
 An: [email protected]
 Betreff: Re: AW: Re: AW: Re: AW: Re: AW: Re: AW: Re: Aw: Re: AW: [EVGRAY] Re: Kone & Hector, you guys finally did it!
   Hi Sven,
 
 My guess is that the transformers are made for being cheap. If made for microwave ovens they are only used intermittently at full power thus no problem. For continuous standby use they may be energy consumers if having too much resistance that dissipates the power as heat (active power) or Watts. If the power is pure reactive (VA-reactive) across only some few Ohms of resistance no problem too as very little heat dissipation takes place then. But it does look like some saturation is happening.
 
 Regards
 Ole
 
 
 ---In [email protected], <s.friedrich@...> wrote :
   Hello Ole,
 
 the differences between the voltages are very different as far as the current consumption is concerned. Actually, one should assume that the transformers should actually behave fairly evenly, at least linearly, the current should increase with increasing voltage. What I particularly noticed is that a transformer is a bit louder than the other or just has a different pitch.
 
 How to tune a transformer so!?! I could imagine that it is synonymous s.der core but there I have no influence on it.
 
 regards
 
 Sven