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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33 views

Can switching between two unsynchronized sources cause problems for an average office building?

We have a 100kW 3Φ 208V generator and ATS operating in North America. The system as installed does not allow for a test where the load can be placed on generated power when utility is available. We ...
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1answer
63 views

Confusion in modelling of total loop Inductance of a rectangular loop

I was reading an article about partial and total loop Inductances from this site and in a section where for calculation of total Inductance of a rectangular loop is given as - In each portion of the ...
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19 views

Tertiary control loop in Automatic generation control of Power system

Here I need help with AGC related research paper. I have certain confusions about tertiary control... Why do we use tertiary control loop in automatic generation control of Power system? Because ...
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14 views

NEPLAN Load Flow Analysis with 1-day measurement

currently I am working on a project to identify energy loses in an electrical network. I am using NEPLAN 10, and already build a small system and implemented measurements. As soon as start the ...
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3answers
77 views

How does electricity from a 3 phase 4 wire 480Y/277v EV meter differ from a standard 120v wall outlet?

I am wondering what the difference is the electricity that comes out of the switchboard/utility meter that is designed to be a separate meter to measure a customer's use of power that only goes to an ...
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4answers
136 views

what role does transmission line termination take in long distance power lines?

Does transmission line theory and transmission line termination take any significance when dealing with long high-voltage power lines? Do power companies terminate their power lines to avoid ...
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3answers
170 views

Is there a circuit element which dissipates energy but does not act as a resistor? [closed]

I know this sounds a bit weird, but is there a circuit elements which dissipates energy if a current flows through it but is not a resistor? In other words, is there an energy sink which does not ...
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0answers
51 views

Can electronic devices be installed on the pillar of UHV towers such as 345kV?

Can electronic devices be installed on the pillar of UHV towers such as 345 kV? Because I have an idea to install a remote automatic control electronic device on the tower to control the rotation and ...
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42 views

Inductance of composite conductor

Why L is calculated using average value and not by the formula 1/L = 1/L1 + 1/L2 + ...
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2answers
40 views

Delta-Wye transformer differential protection during external line to line faults [closed]

During these kind of line to line faults current flows in the faulted phases of the secondary and all phases of the primary as it is shown in the image. So now the currents in phase A are not equal to ...
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58 views

Calculating the line-to-neutral voltage of a generator

A three-phase generator is connected to a strong grid with line-to-line voltage 14 kV and frequency 50 Hz. The generator is rated at 15 kV and 180 kVA. The resistance in the windings is 2 Ohm/phase ...
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29 views

Selecting the correct wire for very short power transmission

Looking for the thinnest wire for very short distance power transmission. Supply is 5V, 10A. Ambient temperature is 35C. There are 5 consuming elements, each consuming 10W. The elements are linked ...
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3answers
48 views

What happens when a multi-fuel generator reaches capacity on LPG or NG?

I have a multi-fuel generator rated for 7.5KW on gasoline, 5.5KW on natural gas. It has a 30A circuit breaker that will trip if demand exceeds capacity on gasoline I would like to understand in some ...
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22 views

How much information would a network protector need to determine if a backfeed is due to feeder failure or power export?

Many downtown or otherwise densely built-up areas, as well as some major metropoles (much of NYC, most notably), use secondary network electrical service to maximize service reliability and keep ...
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2answers
59 views

frequency for a 90° phase shift [closed]

It seems an easy question but I just can find out how I'm supposed to do it: what frequency is needed so that Vin and Vout have a 90° phase shift. (picture below just as a matter of an example circuit)...
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How can energy “physically” be fed back into the grid?

I have found some similar questions (below), but I am still having issues understanding what is "physically" happening when energy is "fed back into the grid" and the equipment ...
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50 views

Offgrid backup AC power option

I’ve been building an off grid home for a few years - recently moved in full time. Living in VT, with limited solar, we depend on a Honda EM6500SX 240v generator to occasionally recharge 20 batteries ...
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57 views

Convert AC grid to DC and back to AC grid same phase

I would like to execute long time running transistor switch tests with high currents. I would like to source AC power from grid, convert it to DC, pass through my transistor switch, after that I want ...
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1answer
47 views

How are ground wires and OPGW connected to ground and neutral point of transformer, and to the com.system?

Note: This question is about power systems in the kV, MVA range. Many distribution and transmission systems are impedance grounded, which means that (some of) the transformer neutrals are connected to ...
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1answer
54 views

Two electrical sources for one load

How can two electrical sources 220 volts feed one electrical load about 20 amperes where the first power source spends all its capacity and when required the remainder is taken from the second source?...
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2answers
730 views

How generator becomes under excited/ over excited?

I keep reading in power system notes that a generator when under excited/ over excited either absorb/ release reactive power. Question is, what determines these under excitation and over excitation? ...
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16 views

Can we control the data sending by Phasor Measurement Unit (PMU)?

Since PMU send the data after sampling the data to the PDC. Can we design any scheme so that PMU send the data to PDC only when I want? That means to reduced the communication bandwidth can we design ...
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1answer
96 views

Why are current transformers used in power stations?

I read that surge arresters in power stations suppress the high incoming voltage and the output passes on to the current transformer. If surge arrester already reduced the voltage then why is the ...
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3answers
2k views

Australia–ASEAN Power Link - why not build the solar farm near Singapore?

World's Largest Solar Farm to Be Built in Australia The 10GW, 120 square km solar farm in Australia is connected to Singapore via a 4,500-kilometre high-voltage direct current (HVDC) network. The ...
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1answer
106 views

What cause sudden spike in the output voltage of transformer?

What issues can cause the output voltage of a transformer to suddenly increase from 230 volts to 400 volts (in the case of any transformer and in the case of the delta to Y configuration of the ...
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2answers
168 views

Transmitting VCC and GND signals for use with RS-485

The specific question I want to ask is whether I can transmit VCC(5VDC) and GND power signals for powering the destination circuit (in an RS-485 arrangement) or not. The power lines will be grouped ...
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49 views

Reactive power of a discharged capacitor

I was wondering if a DISCHARGED capacitor connected to a grid gives to this one a positive reactive power. Is it yes? If not, it's true to say that only charged capacitors gives positive power to the ...
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32 views

Equipment for analyzing large DC distribution system

I'd like obtain the transfer function of a large DC power distribution system. My question is whether there's equipment (like vector network analyzers) designed to assist with modeling these type of ...
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0answers
77 views

Nodal voltage magnitude properties of electricity distribution networks

I am wondering how to know about an electric bus according to its measured voltage magnitudes (possibly and its corresponding real power injection profile). Following assumptions can be made: One ...
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2answers
187 views

Need help to understand inductor based non-isolated offline buck converter [closed]

Here ADGJ IC is used in offline buck topology. Can anyone share the schematic of it. Picture taken from sonoff mini and shelly1 board is attached below
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37 views

Where do I find electrical power transmission grid data?

I am looking for websites which provide datasheets of 3 phase electrical power transmission networks with information about their ...
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1answer
44 views

About signal conversion

Question is weird but it's about something that I really want to try. AC power here in India has 50Hz frequency. What I really want to try is to make a series path with two continuous conversions. In ...
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71 views

Laplace vs Fourier Transforms in Transmission Lines

Consider an electric transmission line with transient equations $$\frac{\partial v}{\partial x} =-Ri -L\frac{\partial i}{\partial t}, \qquad \frac{\partial i}{\partial x} =-Gv -C\frac{\partial v}{\...
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2answers
69 views

Phase voltage in impedance grounded vs solidly grounded system during ground fault

Why does a phase-ground fault in an impedance grounded 3-phase system lead to variation of voltage in healthy phases but this variation doesn’t happen in solidly grounded systems? I was thinking about ...
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1answer
39 views

Transformer cooling difference between water cooling and air cooling [closed]

I just know air cooling method is cheaper than water cooling method. Please tell me what is the difference between air cooling and water cooling? And if you could please use some pictures to explain ...
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3answers
150 views

Which Source of Energy Comes First?

When there are multiple sources of power, how is it determined which one is used? or are they all split? Easy example is a grid tied solar system. If you have grid power in a breaker box and also ...
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2answers
98 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
55 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
118 views

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

I have attempted to solve this problem, but the answers don't match. Where am I making a mistake?
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52 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
72 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
44 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
27 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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22 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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26 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
95 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
238 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
375 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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