Re: 41cv charger what is voltage? Message #6 Posted by Reinhard Hawel on 25 Mar 1999, 5:35 p.m., in response to message #5 by Raśl F. Rueda
You are right.
Our measurements:
my charger 230V/50Hz: 12.4 VAC unloaded yours 220V/60Hz: 11.1 VAC unloadad
I should note that the eurocharger is rated for 2.5VA, not for three. I was inexact in this point. I also wanted to point out in my former post, that it will surely work and all other differences were neglectable in this case. Now a more exact calculation.
I don't have the LCR meter yet, so I haver to use your values, which seem realistic. However there can be significant tolerances, which can make a comparison with measured values completely useless. I therefore refer to your L, values and the Voltage as rated in our countries.
A short calculation shows the difference between the two cases:
secondary yours: XLs=2*pi*60Hz*63.6uH = 23.98 mOhms
mine: XLs=2*pi*50Hz*63.3uH = 19.98 mOhms
primary yours: XLp=2*pi*60Hz*22.3H = 8407 Ohms
mine: XLp=2*pi*50Hz*22.3H = 7006 Ohms
I don't have the value for the copper resistance on your charger, so I have to neglect it. I'm sure that it is much lower than the XL. Please measure. I don't like to take the values of mine. BTW it would be of interest measuring the value of Rcus (Copper res secondary too). This may be considerably high against the XLs and show an important load condition, when the charger is loaded with, say some Ohms. The charger cannot be destroied by shorting the secondary side, as the symbols on the charger show (in german the =OO] sign on the right lower side of the side means "absolut Kurzschlussfest" = "absolutely short circuit proof"). You may have to check this out on your transformer. It could be of interest measuring the shortcircuit current or put a load of some Ohms on the transformer. Maybe I could do this in the next days.
I also neglected the inner resistance of the mains supply which can vary much even between two different plugs. In any case it is much lower than XLp.
I primary yours: Ip=220V/8407 Ohms = 32.82 mA
mine: Ip=230V/7006 Ohms = 26.16 mA
NOTE: I think that we should measure the series copper resistances Rs and Rp and calculate the values of Zp and Zs. This will surely give more exact results for this calculation. The other losses a transformer contains (curl current (is that the right word for "Wirbelstrom"?) in the iron) are not that easy to measure and are neglected for this case.
