25
votes
Can't the electric current returning from the neutral end of the electrical cables be used again?
There's an easy to understand comparable case (see NOTE1): Water above the dam falls down through a pipe and rotates a turbine. Why do we let the water go away? Why do we not let it rotate another ...
- 349
18
votes
Accepted
Staying in Phase On The Grid
Before connecting a generator to the grid, they spin it up to more or less the right speed. Then they hook what is basically a voltmeter between a generator phase, and the corresponding line phase. ...
- 174k
16
votes
Staying in Phase On The Grid
You're confusing an accurate number of cycles over a 24 hour period with very rigid instantaneous frequency control. That's not how it's done in most places.
The frequency is maintained at around ...
- 161
16
votes
Transformer 220/380/440 V 24 V explanation
That looks like it has a tapped primary and you connect the input voltage between '0' and whichever of the taps matches your input voltage.
simulate this circuit – Schematic created using ...
- 27.8k
16
votes
Can't the electric current returning from the neutral end of the electrical cables be used again?
But the current does not return to ground.
You should perhaps consider the mains wires (live and neutral) like a bicycle chain, drive belt in car engine, or closed loop water circulation heating ...
- 172k
13
votes
How to find phase angle from transfer function
It is just a matter of manipulating complex numbers.
$$ \angle H(\omega) = \tan^{-1} \left( \frac{\Im\{H(\omega)\}}{\Re\{H(\omega)\}} \right)$$
Where \$\Re \{ \cdot \} \$ is the real part and \$ \Im ...
- 344
12
votes
Accepted
About power dissipation of capacitors and inductors & I-V phase difference
If the voltage across a capacitor is described as sin(x), then the current through the capacitor (being 90 degrees out of phase) can be described as cos(x). The power is given by the product of ...
- 16.4k
11
votes
Accepted
240 V split phase and 240 V single phase
The power feed to a North American residence is normally provided by a center-tapped transformer, with the center tap of the transformer secondary grounded. the full secondary winding produces 240 ...
- 60.7k
10
votes
Accepted
What does actually the "unravel branch wrap" option do to the phase plot in LTspice?
It adds or subtracts multiples of \$2\pi\$ (360 degrees) to each point in the phase plot so that the phase is plotted continuously rather than having jumps in it.
We know that physically the phase ...
- 174k
10
votes
Accepted
Clock Phase Shift Not Working on FPGA
When there is a 90° phase shift between two 5MHz clocks, that means there is a 50ns skew between them.
If you divide those two clocks by 5000000 using two instances of the same counter structure, you'...
- 1,828
10
votes
About the torque-free charging operation
The paper is about using the EV motor windings as a transformer or inductors as part of the charger when the vehicle is charging instead of using a separate component.
A common problem of doing so is ...
- 34.2k
10
votes
Accepted
Why multiple series resistor on single phase metering reference design with HLW8012 and BL0937 IC
The main reason is the voltage rating of the resistor. Finding a 1.2MOhm resistor in ,say, 0.25W with a voltage rating of 600V or so is more difficult or expensive than using a string of common garden ...
- 6,678
10
votes
Accepted
How can current phase shift be 90 degrees behind voltage just "inside the capacitor" on an RC series circuit but be in phase in the resistor?
He does say, at 13:12 "that 90° phase shift only happens in the capacitor", which is an unfortunate choice of words. The word "in" or "inside" might give the impression ...
- 47k
9
votes
Why do some op amps' datasheet specify phase margin at open loop?
Shouldn't it be just phase?
I agree.
It makes no sense to draw a graph like this and call it phase margin because, phase margin usually only occurs in one place i.e. where the open-loop gain is unity....
- 473k
8
votes
Find the phase angle between two functions
Additionally, it seems to me which function leads which is rather relative as I can shift any function 360 deg, any easy reconciliation?
Absolutely. What is leading or lagging is up for ...
- 99.9k
8
votes
Active RF signal repeater
First of all, your transmitter A would be illegal. And any conductive surface reflects electromagnetic waves; at 10 MHz, a sufficiently large metal sheet would do; there's no point in an active ...
- 99.9k
8
votes
Can't the electric current returning from the neutral end of the electrical cables be used again?
We'll examine your idea with a simple DC circuit. Here we'll use the DC negative as "neutral".
simulate this circuit – Schematic created using CircuitLab
In Figure 1a you can see that ...
- 180k
7
votes
Staying in Phase On The Grid
They use a Synchroscope. I have seen this done in power plant control rooms.
https://en.wikipedia.org/wiki/Synchroscope
- 407
7
votes
Accepted
What is the purpose of these elements in this circuit?
Figure 1. Waveform amplifier.
The resistors form a half-supply reference for the single-rail powered op-amps. With a 5 V supply this reference voltage will be 2.5 V. The 100 uF capacitor stabilises ...
- 180k
7
votes
About the torque-free charging operation
The author is talking about charging an electric vehicle by re-using its drive train electronics and the motor windings as parts of the charging circuit.
This means that during charging, currents flow ...
- 20.5k
7
votes
Why doesn't the bypass capacitor cause phase shift in this oscillator circuit?
As far as the oscillation condition is concerned, it is the phase shift within the feedback loop that only matters! Therefore, the coupling capacitor at the collector node has practically no influence ...
- 28k
7
votes
Accepted
Phase modulation for binary data - higher frequency harmonics?
You are correct. The jumps in QPSK do generate high frequency spurious signals, as do the changes of slope that you've shown in BPSK.
The solution is that the signal from a modulator like that is ...
- 174k
7
votes
Accepted
Why do some op amps' datasheet specify phase margin at open loop?
Yes - it is a mistake. The wording just below the diagram ("Gain and phase vs. frequency") is correct. The phase margin (PM) is just one point of the phase response (it is app PM=60deg).
...
- 28k
6
votes
Can overhead ground wire of major transmission lines prevent induction through solar storms?
EMP from solar winds aka Carrington effect happens every hundred years or less (due to solar cyclic wobble from planet alignment with Jupiter which gives rise to an 11 year cycle) and there are longer ...
- 148k
6
votes
Accepted
Why this motor shows delta 220 / star 380 which is usually the other way round from what I know?
You're mistaken.
The motor phase voltage is 220 V.
When connected in star, the line voltage is 220 * √3 = 380V.
When connected in delta, the line voltage is the same as the phase voltage i.e. 220 V.
- 19.2k
5
votes
Staying in Phase On The Grid
Having parts of an individual power system run at different phase angles from other parts is routine and unavoidable. This is not a problem until it is necessary to re-connect parts. In the Utility ...
- 137
5
votes
Accepted
Snubber Circuit working
Very simply, the snubber provides a load to dissipate energy from rapid changes in voltage associated with reactive components. In your diagram, consider what happens when the triac experiences a ...
- 11.8k
5
votes
240 V split phase and 240 V single phase
I designed electrical systems for buildings since 1983. I think I can make sense of this for you!
Forget the 180 degrees out of phase that you are being told. You have a single phase sine wave on ...
- 51
5
votes
Accepted
Is group delay the same as the delay of a certain frequency?
The group delay is a function of frequency, so you cannot really say it's the same as the delay of a certain frequency -- that would be a particular case. Also, the step response is an infinite sum of ...
- 21.8k
Only top scored, non community-wiki answers of a minimum length are eligible