# Questions tagged [ac-polarity]

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### How to ensure single phase AC polarity?

The device I'm designing needs to have correct power supply polarity but will be connected to mains supply with unpolarized plug. What automatic and IEC standards compliant methods there are to ensure ...
• 395
265 views

### What is the name of this plug, and which side is line and which is neutral?

What is the name of this plug, and which side is line and which is neutral? (Image from Wikimedia Commons)
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486 views

In the figure at right, I believe the terminals are at the following potentials: H1 = 0V H2 = 120V X1 = 0V X2 = 30V Doesn't it follow that the potential difference across H2 and X1 is 120V (not 150V)...
1 vote
387 views

### Merely flipping secondary winding shouldn't affect transformer polarity

The polarity test for a transformer determines whether it has additive or subtractive polarity. I understand that convention is to recognize X1 and X2 on the secondary winding as, respectively, the ...
2k views

### Which of these wires is positive and which is negative?

I know that in DC circuits the colour code is often (but not always) that red is positive and black is negative. On this AC mains wiring the wires are blue and brown. Does anyone know which is which? ...
• 411
907 views

### What is the point of polarized plug in home AC?

Given the fact that with AC, electrons move back and forth, implying there is no real flow from A to B, what is the point of a polarized plug, since either way should do. The only explanation I have ...
• 47
102 views

### Insulate active or neutral?

If you can only insulate active or neutral, which should you choose? Does it matter? Is it important? Is one better than the other?
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128 views

### How do I solve transformer numericals with additive polarity?

Ok, so for subtractive polarity in transformers(dots at the same side of the windings) E1/E2=N1/N2 But if it's subtractive polarity E1 and E2 are out of phase so shouldn't E1/E2=-N1/N2 Edit: Ok here ...
4k views

### Effect of Reversed Phase Polarity on Active & Reactive Power of 3-Phase System?

I am trying to investigate the Power/Energy of 3-Phase System under Different Faults. I have a Three Phase Source and Load, Load is balanced i.e same phase angle and current (Phase-Neutral V = 230 ...
180 views

### Create a polar cap with a diode?

I'm trying to order components, so I can make a board following this circuit. My problem is, I cannot find any 0.1uf capacitors, that are rated at 275VAC. The highest voltage I can find, in stock, is ...
19k views

### Why is this power cable sometimes polarized and sometimes not?

I have a handful of power cables like this: Some have polarized male plugs, while others are not polarized. Given that the female end appears to be reversible, why are some of them polarized? I ...
1 vote
2k views

### Diode - output waveform of a network

Question: Determine the output waveform for the network(assume that all diodes are ideal) The book says for the positive half-cycle it will be like this: Similarly I think that for the negative ...
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5k views

### Three-phase Y and Delta Configurations Polarities

Please take a moment to look at the three-phase Y and Delta configurations pictures below (The pictures are screenshots taken from the “All About Circuits” online book). The first picture (Y ...
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