# Tag Info

Accepted

### Why 3 phase and not 1 phase power transmission?

Why not three lines all in the same phase? Because then there is no return path. Because single phase has no "rotation". Three phase makes it very simple to make a rotating motor with phase sequence ...
• 178k
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. ...
• 169k

### 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

### 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 ...
• 25.5k

• 169k
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'...
• 1,718

### 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 ...
• 33.8k
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 ...
• 6,423
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 ...
• 39.8k

### 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....
• 465k

### 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 ...
• 97.5k

### 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 ...
• 97.5k

### 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
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 ...
• 178k

### 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 ...
• 20.1k

### 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 ...
• 27.3k
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). ...
• 27.3k

### Why 3 phase and not 1 phase power transmission?

I'll focus my answer on transmission alone, without explaining why 3 phase is useful in general because other answers did that. Transmission of power is a compromise. A compromise between ...
• 1,735

### 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 ...
• 145k
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.
• 18.9k
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 ...
• 169k

### 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
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 ...
• 11.7k

### 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 ...
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 ...
• 21.6k