# Tag Info

13

Where that additional 5MW of power came from instantly until the power system frequency go down and active power governors speed up the generators (obviously there is a time delay)? The voltage on the line sags when loads are switched on (which is dependent on resistance and inductance in physical wires; if they were superconducting wires, the load and ...

7

When you connect a new load, it becomes part of the larger circuit. The current starts flowing through the new load. This is a transient process and the associated electromagnetic field propagates close to the speed of light through the entire grid - that is, the change will be detected almost immediately in other parts of the Power grid, even at relatively ...

6

The datasheet only says 50/60Hz and there are no frequency characteristics listed beyond that. It does say that its based off of the M0C2A-60 triac (of which there is no information for) but many triac circuits are 'tuned' with snubbers for zero crossing detection. A different frequency than 50/60Hz would interfere with the zero crossing operation. I'd just ...

4

We can't simply connect a huge load to a power system without informing the authorities(5 MW is really a huge load) When such a huge load is connected to the existing balanced grid, the grid will initially try to satisfy the load requirements. As a result, the voltage and frequency of the grid will drop as the system doesn't know about the But the Automatic ...

4

There's no way of knowing; I'm more worried about the relay not turning off. What is certain is that it isn't specified for it. Also, likely your 3 kHz signal is a power RF signal? You wouldn't want to push that through a non-linear element like a SSR.

4

There are always small fluctuations in both frequency and voltage in the electrical grid. The size of these fluctuations depends on the power of the generators in the grid as well as the load currently present and the load being added. Under normal circumstances 5 MW is not a big load compared to the load normally present in the grid. For example a train ...

3

The expression $$\text{Re}\, [(\vec V_1 + \vec V_2 + ... + \vec V_n)e^{j\omega t}]=0$$ must hold for all values of $t$; this means that it needs to hold when $e^{j\omega t} = 1$ and when $e^{j\omega t} = j$ (as well as all linear combinations of the above); this is only satisfied when the sum of the complex phasors is zero (both real and imaginary ...

3

SPI Master will drive the SPI Slave clock line, there is no way of having those frequencies different. But since the slave has its own limits, the master should not go faster than the slave is capable of supporting. The maximum frequency for ADC SPI interface (SCLK) is shown in Table 2. See the allowed high and low pulse minimum widths. Both are 50 ns, that ...

3

It all depends on the numerator phase angle. This is either $\small\phi =atan\:(\frac{-\omega}{\omega_{1}})=-90^o$, or $\small \phi =atan\:(\frac{\omega}{-\omega_{1}})=90^o$, as $\small\omega\rightarrow \infty$. The denominator phase angle will always be $\small -270^o$, as $\small\omega\rightarrow \infty$.

2

Negative frequencies are not intuitive. They appear in Fourier transforms because those transforms present signals as sums of complex exponentials exp(j(2Pi)ft). Presenting signals as sums of usual sines would be perfectly possible and they would not need negative frequencies, but algebraic manipulations and formula derivations would become much more ...

2

It's not a dumb question. In the case of your graph, the frequency is negative with respect to the centre frequency. So if centre frequency is 10MHz, and we talk about the 3dB points being +/-1MHz, they are 9 and 11MHz. If you want to put a 100MHz square wave through an opamp, you will indeed need a bandwidth much more than 100MHz. Square waves have odd ...

2

You wrote My understanding is that heterodyning is achieved by shifting the measurement light frequency with respect to the reference light frequency by some carrier frequency. I guess you have imagined the next frequency shifting scenario: It's taken from systems which operate at microwaves or lower frequencies. It could in theory also work with light or ...

2

After some helpful clarification, here's a more complete answer. First, to the direction question: how is the light shifted in a heterodyne detection system for a laser Doppler interferometer?" They typically use a Bragg cell (AOM, or acoustic optical modulator). A Bragg cell basically uses phase modulation as a way to cause a tiny shift in the ...

2

Impedance mismatch causes signal reflections, so for each edge in the signal, additional edges are generated as the echoes and echoes of echoes overlap it. This can be tolerated as long as the amplitude of the reflection is small, or the time delay of the reflection is short enough that this only leads to a bad shape of the transition edge, but doesn't ...

2

To first order, the inductance will not vary significantly with frequency, as the magnetic properties of air are essentially frequency independent. If you connect the inductor to an inductance measuring device and sweep the test frequency, then the measured inductance (the imaginary part of its susceptance) will rise as the effect of the coil's self ...

1

When frequency rises both the inductance and the resistance of any length of wire changes, even if there's no magnetic core (dry air at normal pressure has almost the same permeability of vacuum). This is due mainly to skin effect and proximity effect. There is a math-heavy explanation of the phaenomena here: The Influence of Frequency upon the Self-...

1

While other answers are excellent and to the point, there is one thing in the question that pokes me: I know that in a power system there are no energy storage elements. Due to this, as soon as power is generated by the generators it is transmitted to the end user where the power is utilized. There's no long term energy storage. You can't generate a kWh ...

1

Your doubts are well founded. A frequency-varying pure resistance is not a physical thing. As the real part of an impedance changes with frequency, the imaginary part of the impedance is constrained to vary in a particular way. This is due to causality. (look up kramer-kroning relations) So, you can't build a circuit that that varies resistance with ...

1

A lumped element model will be fine up to the GHz range, in the Tera-Hz range that is where things start to break down because materials start to behave different. So if you plug in this model, R would be the resistance of the resistor. L and C can be estimated or measured. L is from the leads and will be really small, in the nH range for most SMT parts. You ...

1

You may wonder why traces of some interfaces are not analyzed by the transmission line theory. Following is simple analysis of impact of trace length: Referring to input impedance of lossless transmission line, $$Z_{in}(l) = Z_0 \frac{Z_L + j Z_0 tan(2 \pi l / \lambda)} {Z_0 + j Z_L tan(2 \pi l / \lambda)},$$ if $l \ll \lambda$, $$... 1 The important thing is the rise time (not the pulse repetition rate) of the signal, compared to the length of the trace. If the signal can make several round trips of the line between the driver and receiver during the rise time of the signal, then we can ignore the transmission line effects. With a trace 200 mm long, which is about 1 ns electrical length ... 1 The line is VERY loosely drawn at about when the signal trace length approximates a quarter of a wavelength of the signal it is carrying. However, much depends on shielding, characteristic impedance, how its driven and so forth. It also depends on the maximum frequency component of the rise and fall times of the signal. So if (say) you have a 100MHz digital ... 1 Impedance matching is always a concern. You always have to pay attention to it. However, with something like an I2C bus, there is a defined way to drive the bus (in this case open collector output with a bus pullup resistor of say 470R) which already takes account of this. Impedance matching is a universal electrical concept which applies any time you try to ... 1 Any method that provides a non-linearity or modulation function of the incoming optical signal by another (usually RF signal) can produce mixing products (heterodyne). Mixing can occur between two optical signals at the receiver diode to produce the difference signal, however although this can be used to provide synchronous optical detection it is not of use ... 1 When you combine two lights together, you add their intensities. Combined intensity is $E_\text{s} + E_{\text{LO}}$ and its power is proportional to square of it$$(E_\text{s} + E_{\text{LO}})^2 = E_\text{s}^2 + 2E_\text{S} E_{\text{LO}} + E_{\text{LO}}^2.$$The $2E_\text{S} E_{\text{LO}}$ is important because multiplying sine-waves results in adding/... 1 Given Phase approaches $\Phi$ at high frequencies (or 0 frequency); And a transfer function which you can rewrite in the form$$ H(s) = \frac{N(s)}{D(s)} = K \cdot \frac{\prod_{i=1}^{n} (s-z_i)}{\prod_{j=1}^{m} (s-p_j)} $$Finding the relation between angle and K At high frequencies, $s \rightarrow \jmath\infty$ ans so $s-c_i \approx s$. So,$$ \begin{...

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