Variable Auto
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auto transformer question?
Okay, so I was working with a variable auto transformer recently and got a couple of questions.
So, I got it hooked up with a parallel load combination with a resistance of 34.5 ohms.
I was taking readings and the no-load input power and current aren't zero. Why weren't they zero?
-Also I'm having trouble calculating the auto transformers magnetizing current and current supply the core loss.
-I have the input current, volts, watts, VARS and power factor. What equation would I use to find the magnetizing current and current supplying the core loss?
If you take the no-load readings you mention then no 34.5 ohm resistance should have been connected. This resistance and load are irrelevant to the rest of your question
No load input power and current are not zero because the primary winding, on no load (secondary on open-circuit), constitutes a high inductance which will draw some small current and power.
To determine the magnetising current and core loss you need the values of your last paragraph at no load. If the total current = I then the magnetising current = I.sinϕ where ϕ is the power factor angle (power factor = cosϕ). The core loss is the real power supplied on short circuit = watts measured on short circuit. There is a small correction for winding loss here but at the low level of open circuit current this may be neglected without much impact on the result.
Suzuki Automotive Explains "CVT" or Continuously Variable Transmission
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