Ralph Mowery wrote:


I know that a capacitor does not consume any power if connected across an AC
line except for a small ammount , but lets just say a pure capacitance.

I was playing around with a meter similar to the Killowatt meter and with a
hair dryer the voltage and current multiplied together came to the same as
the displayed watt on the meter within a few percent. Then I hooked up an
amplifier that has a transformer in it and the displayed power was about 80%
of the volts times amps.

** That is rather high, normally is it closer to 65%.

IOW transformer fed PSUs have a PF of 0.65.


I then hooked a 50 uF capacitor across the line, only the capacitor. Just
rough numbers calculate the capacitance reactance as 53 ohms at 60 hz. Sure
enough the meter shows about 2.3 amps just about what a 50 ohm resistor
would show. However the wattage display was about 2 watts which still
seems normal due to a slight leakage and such. I understand the meter
showing this due to the lead or lag of reactance and wattless power.

Finally getting to the question is that if I bring up the AC up slow with a
variac to keep the main surge down would a 1 amp fuse blow at around 50
volts when the current got past 1 amp or could I keep going to the full 120
volts AC ?

** Strange question.

The fuse will blow when its current rating is exceeded by a sufficient ratio - about 50% or so.

That the load is a capacitor ( with current and voltage not in phase) has no effect.


.... Phil