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7 votes

How can failure of Class Y capacitors lead to electric shock?

It would potentially lead into hazardous situations if an Y capacitor would fail into a short circuit. However, Y capacitors are special safety capacitors that are specifically designed to fail into ...
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5 votes

How to hook up a transformer to 120V AC?

Connect hot (usually black) of your cable to one primary (black) lead of the transformer. Connect neutral (usually white) of your cable to the other primary (black) lead of the transformer. Connect ...
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4 votes
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How can failure of Class Y capacitors lead to electric shock?

In an ideal world a Y-Capacitor failing short would trip a safety device, either a fuse or a GFCI will trip. Sadly, your world is not ideal and a ground path has a lot of ways to be broken. It's a ...
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3 votes

Why does reactive power not output useful work in a motor?

isn't negative power also generating useful work? Reactive power is not negative power. Positive (real) power would be defined as either power flowing from source to load (or load to source) while ...
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3 votes

Inductive power capture from AC power cable

To extract power from a single conductor current carrying cable, you wrap a magnetic core round the conductor, making it a one turn primary of a transformer, and then a secondary coil round that core. ...
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3 votes
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How to safely protect input sensing AC Line Voltage

Anything you'd add? Is this overkill? You don't say what part of the world this is going to be in, but the mains are very nasty in many places. For better reliability I'd do something like divide ...
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3 votes

Can a bipolar capacitor in an AC circuit store even a tiny amount of energy?

Yes, there can be some energy stored. If the supply is disconnected at the peak supply voltage, this could be as much as 1.41 times the RMS supply voltage. That's about 325V for a 230V AC supply. For ...
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2 votes
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AC voltage and frequency as complex number?

Is there any common representation of voltage and frequency as a complex number? You shouldn't do this. First, as others have pointed out, complex numbers are often used to represent the magnitude ...
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2 votes

Inductive power capture from AC power cable

What you describe, is a very poor transformer with bad coupling. The power that you take from the wrapped wire is not for free but will load the mains cable (aka primary) in the same way as in a ...
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2 votes

Why does reactive power not output useful work in a motor?

A motor is a bit more complex than an inductor. With an inductor, an AC current converts input electrical power into magnetism, then magnetic energy is converted back into electrical energy returned ...
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  • 1,052
2 votes

How to hook up a transformer to 120V AC?

You can use either of the black wires for neutral and hot. You should connect the earth wire. The transformer is Class 2 but is not an impedance protected type, so it contains a thermal fuse or ...
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2 votes

Why does reactive power not output useful work in a motor?

Some clarification is needed to correct misunderstandings. Generator power is negative, and loads use positive power. Reactive current in AC is cyclic (+/-) but is out of phase by 90 degrees to ...
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1 vote

A couple of questions about transformers

You can't supply a signal with a DC component to a transformer. So you can't (shouldn't) apply a 'square wave DC signal' (there's no such thing). If you apply an AC-coupled square wave, you'll get a ...
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1 vote
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How can I set the peak voltage in an AC waveform?

The EMF (voltage) of a coil in a generator is the negative of the rate of change of magnetic flux that passes through the coil. You have a few ways to increase this: Use a stronger magnetic field (i....
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1 vote
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Relation between line voltage and phase voltage in delta configuration

If I understand that what you are asking is "why are the sums of the other two phases equal to the phase I am looking at". The other two phases are 120 degrees and 240 degrees shifted in ...
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1 vote
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What happens if you connect an AC generator to an AC motor?

...they should power each other... You seem to be imagining that a "generator" only converts mechanical energy to electrical energy, and a "motor" only does the opposite. The ...
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1 vote
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Is it a good idea to drive 24VAC solenoid valves with triacs?

Most modern irrigation controllers use triacs to control the solenoids. However, relays work also well and have the possible advantage of galvanic isolation between the control and load sides of the ...
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1 vote

Is it a good idea to drive 24VAC solenoid valves with triacs?

You can use relays or you can use MOSFETs or FETs or BJTs which are inexpensive too and have good current handling capacity (assuming you will be using any microcontroller for triggering the MOSFET at ...
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1 vote

Grid is capacitive in the evening

This is a new answer to an old question. simulate this circuit – Schematic created using CircuitLab If we simplify the grid feeder transmission lines with some mH/km and nF/km for each line, ...
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