Questions tagged [power-engineering]

Power electrical engineering. Includes industrial electrical engineering (i.e. motors, switchboards), transmission and distribution (poles, wires, transformers, grids) and generation.

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55 views

Voltage Collapse in Power Systems: Loss of steady state?

I've read some papers on voltage collapse, and it seems to be described as the loss of a steady state solution for the system equations. Where the Jacobian matrix is singular, and voltage is ...
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1answer
44 views

Induction cooker power receiver

While building some small (single digit wattage) inductive power transmission systems, I wondered if a larger one could be build using an induction cooker as transmitter. What would be the mandatory ...
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0answers
39 views

DC Distribution System Numerical Problem [duplicate]

I have attempted to solve this problem but the answers don't match. Where am I making a mistake?
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65 views

Where is my mistake in this power distribution system homework question? [closed]

I have attempted to solve this problem, but the answers don't match. Where am I making a mistake?
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0answers
20 views

Smart meters data correction average time

In the context of smart grids, what is the average time delay of measurements correction provided by smart meter data/AMI data, given that some of the meters may provide incomplete readings because of ...
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26 views

Transmission line current magnitude

I want to compute the current magnitude in a transmission line. The line has properties b (total line charging susceptance, p.u.), ...
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1answer
56 views

Why will we get the wrong answer if we use \$I_1=\frac{V_1}{Z_1}\$ to calculate \$I_1\$ directly?

There is a transformer with \$600V/120V\$, and the impedance in the high voltage side is \$52-30j Ω\$, and there is a loading, which impedance is \$0.8∠10°Ω\$, connected with the low voltage side. ...
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2answers
36 views

Troubles on understanding datasheet of a 24V DC permanent magnet motor

Can you help me on understanding this datasheet of a DC Permanent Magnets motor? Note that the deleted parts do not add information, they are those not translated into English or referring to other ...
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2answers
57 views

Which solution is right for this question? I think both of the solutions make sense

There is a multiple choice question: $$V_{G1}=10cos(10t+60°)$$ and $$V_{G2}=5cos(10t)$$ The resistance of the wire is \$R=10Ω\$, which one is the power that \$G_1\$ transmits? A. 1.25W B. 1.5W ...
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0answers
21 views

TN-S system neutral point earth resistance

According to many sources on the internet, a secondary neutral earth resistor is added at the distribution stations (transformers) to reduce the earth fault current. My question is when using a TN-S ...
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0answers
19 views

Why can the total connected load be equal to system capacity ? what does “maximum demand of the entire system” really mean?

I read some factor in the power transmission ,and there are something i don't really understand Question 1 demand factor \$ = \frac{maximum \ demand}{total \ connected \ load }=\frac{maximum \ ...
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19 views

How to handle duty cycle below deadtime in 2- and 3-level inverters

When programming a pwm for a 2-lvl inverter what would be the suggested strategy for a duty cycle close to 0% or 100%, meaning when I cannot guarantee for dead time. What would cause less distortion ...
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25 views

Currents injected in the grid, connecting a wind turbine

I'm studying the connection to the grid of a wind turbine through a three-phase inverter. Now I understand that , in normal operating conditions, in the connection to the grid, the reference for id ...
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2answers
89 views

Can anyone explain HVDC transmission to me?

HVDC transmission system sounds strange to me because I wonder why we would need it? We have HVAC transmission system which is much more efficient and less power losses. When we use the DC for same ...
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1answer
63 views

How can there be a zero sequence current in a single line to ground fault with an ungrounded neutral

The circuit that describes a single line to ground fault in a system with an ungrounded neutral is: I neglect capacitance between phases and only look at capacitance to ground. The definition of zero ...
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2answers
349 views

What is this symbol that looks like a 3/4 circle connected to wires?

I am reading an application guide related to high-voltage DC and have come across a symbol that I do not recognize: The source of the schematic is this document from Siemens. Based on the context, ...
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6 views

How to find and change the label of the Truth Table present in Simulink through command window in Matlab?

I want to change the function of the truth table present in Simulink through the command window of Matlab. I am able to do it but, when I try to run the simulation it gives an error of 'tt_blk_kernel'....
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1answer
21 views

How to choose a 50 Ohm RF attenuator for radio, bluetooth and wifi power measurements

I have built a power meter with AD8318, a chip which contains a logarithmic amplifier, often used for power measurements. I have read its datasheet and it is written that the maximum input power is ...
2
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1answer
41 views

Difference between single circuit and double circuit transmission line protection systems

I'm doing a research on long three phase transmission line protection systems and I found many schemes such as distance protection, merz-price voltage balance system, split-conductor, "translay" ...
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2answers
28 views

In a transmission line, does the real current interact with reactive impedances?

simulate this circuit – Schematic created using CircuitLab According to the diagram above, if real currents do not interact with reactive impedances, then reactive loads should not worry the ...
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1answer
54 views

Can my solar inverter be significantly driving UP my power consumption or my meter counting excessive production as usage?

I've had a 1.5KWh PV solar system for 3 months now and as any new user I've been monitoring the power generation closely. I've wanted to correlate the power generation to my power usage so I've ...
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4answers
109 views
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2answers
68 views

What does 6kV , 5MW 90% efficiency at full load with 0.9 Power Factor lagging represent for a motor?

I am confused with I see such a statement like the following statetment: Motor with 6kV , 5MW 90% efficiency at full load with 0.9 Power Factor lagging. Could anyone explain it in simple words ?
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22 views

What is this eqation represent in Voltage phases?

I have three pahse load star connected, by per unit $$ |Vab| = 0.9 \\|Vbc| =1.16 \\ |Vca|=1.0$$ the phase angle is chosen $$ Vab = - 90 $$ then the next equation is used to find the different ...
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15 views

The proof of the inductance of three-phase circuit,i can't calculate the correct GMR or GMD

Here is a three phase circuit,and the inductance of \$a ,\$ is \$L_a=2 \times 10^{-7}ln\frac{GMD}{GMR}=2 \times 10^{-7}ln\frac{D}{r'}\$ I want to prove this,but it seems that my calculation is ...
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1answer
89 views

Armour loss in underground cables [closed]

What are sheath and armour loss in underground cables?How can these be prevented?
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2answers
74 views

What is the air gap area?

I found in a book the air gap area is \$Ag= (W+l_g)*(d+l_g)\$ However, I know therectangular prism is \$A=2*(w*d+d*lg+w*lg)\$. Could any one please help me what they have air gap equals \$Ag= (W+l_g)...
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26 views

Finding the impedance of a distribution line from R,X,C values

I have real industry data of distribution feeder with line data consisting of r ,x and c values as shown in the attached figure. ...
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1answer
27 views

Which case count as leading PF in Salient plot generator?

In the figure above we can see the location of two armature currents. In case 1, \$I_{a1}\$ is leading \$Vt\$ (terminal voltage) but lagging \$E_f\$ (excitation voltage). In case 2, it is obvious that ...
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0answers
28 views

High voltage pulses amplification

Let's consider this scheme: With this scheme I wanted to get a pulse of duration 10uS with very high amplitude, starting by the same pulse with 10V amplitude. I need to get a peak of about 400V (...
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1answer
41 views

Inductance of a three-phase transmission line

I was studying the difference between distribution and transmission lines and read that, because of the larger separation among the conductors, the transmission lines have comparatively higher flux ...
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1answer
115 views

Ghosting on Nixie Tube Clock

I have problem with my nixie clock. There are ghosts when changing numbers on the lamps. I'm using multiplexing with TLP627 opto-coupler to control anodes and NPN MMBTA42 bipolar transistors to ...
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2answers
37 views

Instantaneous and active power in an ideal switch powered by real source and squared wave

This is a somewhat theoretical question, but one that has some impact on power theory. The circuit in the figure is composed of a real DC source (with non-negligible internal resistance) and feeds a ...
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1answer
35 views

Quantify Grid Stiffness

Being the stiffness of the grid its capability of maintaining the voltage constant despite small variations on load. Whereas, a weak grid would be easily affected by load variation and the voltage ...
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0answers
37 views

Transmission Line Impedance 3 phase

I have the following question that I can't seem to figure out. The question ask to solve for the impedance of a 3ph transmission line. I've found the De (distance relative distance) and XL using the ...
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1answer
66 views

How can I compute the power flow for a network with transformers (as in the WECC 9 network)?

I'm trying to solve the power flow for the WECC-9 bus reported below: all generators (1,2 and 3) are behind a transformer, which has a Voltage converter ratio (e.g. 18/230) and a reactance(?), which ...
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2answers
103 views

How does the arc extinguisher work in a miniature circuit breaker?

In a miniature circuit breaker, as shown below, the distance between open contacts is much less than the distance between metal bars in the arc extinguisher part (the gap gets progressively longer ...
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28 views

Grid Tie Inverter Anti islanding

I was wondering about anti islanding design. Using grid tie inverters is usually the best choice when not investing in batteries, but suppose you have batteries and want the confort of grid tie AND ...
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0answers
152 views

What will happen if the prime mover driving synchronous machine is accidentally disconnected?

What happens to a synchronous machine connected to an infinite grid, acting as a generator, when its prime mover fails i.e. when mechanical input at the shaft reduces to 0? I'm assuming that the ...
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0answers
31 views

Power management switch for Low-Power Application

In my low-power application I have a MCU waiting for an interrupt to wake up. (see picture) There are two sensor ICs (IC1, IC2) which consume very little and wake up the MCU via the interrupts. After ...
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0answers
26 views

Why the Photovoltaic(PV) variations may cause shutdown in the main grid

If we assumed that PV generator is connected to the main grid, as the PV depends on solar irradiance it is considered to be a variable source. If the PV source can cause variations that could be ...
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0answers
123 views

Can we use the Halbach array configuration in an electromagnet?

I tried asking this question in several forums but didn't find any answers as i expected. It's very hard to find information about halbach array in google, especially in the electromagnetic field. We ...
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5answers
13k views

What is the speed of “electricity”?

In a distribution grid, what is the speed of energy signal Is it strictly the same? And how is synchronisation achieved? Is an electric grid essentially an orchestra where everyone is the chief ...
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3answers
516 views

Producers consumers balance in the grid

In a large distribution grid, it is said that consumers and producers must be in balance; what that means physically, in correct (not simplistic) mathematical formulation, is not clear: perfect ...
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1answer
61 views

Constant current and constant voltage control of inverter

Most of inverters in the grid are based on constant current control where inner current control loop tries to limit the current. Hence acting as a constant current source. I was wondering how control ...
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1answer
33 views

IEEE test system accuracy and transmission line connections

In practice, do transmission lines ever directly connect two electrical generators to each other? Or is it more common for two generators to be connected indirectly through a substation? In the IEEE ...
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1answer
52 views

linear model of a power load at the end of a transmission line

I am working on a controller that will regulate the voltage at the end of a transmission line into a variable load. I am able to ignore the inductive effects of the line at the frequencies of interst, ...
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3answers
63 views

Real Power or Reactive Power in Superconducting Motors?

My circuits class is teaching that in AC power, there are two kinds of loads. One is a resistive load, with absorbs power at all times. The other is a reactive load, which absorbs zero average power. ...
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59 views

How is AC load distributed across on-site generation and the utility?

I’m trying to understand the physics behind AC load distribution when distributed on-site generation is installed and the load is also connected to the grid. In the diagram below, I have a building ...
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33 views

How is voltage induced in Yd transformer without neutral connection sinusoidal?

Thia is regarding bank of 3 single-phase transformers having star connected primary with isolated neutral and delta connected secondary. I know that for bank of 3 single phase transformer core flux ...

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