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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1answer
260 views

What are these parallel connected lines meant for?

During my walk today, I noticed these small parallel connected lines. What purpose do they serve?
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3answers
54 views

How do appliances prefer to use my solar power from a grid-tie inverter over the power from the grid?

I have a grid-connected solar inverter. In the swtich board the incoming wire from the street, the incoming wire from the inverter and the outgoing wire to the loads in my house are all connected ...
3
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1answer
53 views

How does a grid-tie solar power inverter know when the mains power has failed?

Solar power inverters that send excess solar power back to the grid are (usually) required to shut down if the grid power fails. (This is to protect people working on the power lines.) The inverter ...
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2answers
6k views

Primary and secondary substation equipment

There are many devices that can be found in the substation. One of the categorizations for substation is between primary and secondary substation equipment. Which device types belong to each ...
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2answers
92 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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0answers
44 views

How close can a circuit board be to an overhead power line without being effected by EMI?

I am researching a technology that will need to put some circuitry near a power line used on the electric grid and I was trying to determine how close can I get to the power lines with my circuit ...
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2answers
60 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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5answers
3k views

Why do generators have to rotate at a slower frequency if demand outpaces the supply?

EU residents might have noticed that some of the clocks in their house have been running out of sync with other clocks. Apparently, the cause for this is that power suppliers had to reduce the ...
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3answers
1k views

Different colors for Power Transmission Towers

I have observed that some areas have some power transmission towers painted in Red and white colors. But, more often, transmission towers are unpainted. An illustration of what I mean by this, Left: ...
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2answers
194 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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0answers
20 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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0answers
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
79 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 ...
3
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6answers
8k views

Calculating CCA of a starter battery

I'm searching for some kinda of formula that can be used to calculate the Cold Cranking Amps (which seems to be an industry term for a 30 sec discharge pulse current at a specific temperature, 0 ...
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4answers
137 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
176 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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0answers
46 views

Inductance of composite conductor

Why L is calculated using average value and not by the formula 1/L = 1/L1 + 1/L2 + ...
3
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2answers
41 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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0answers
60 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 ...
17
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4answers
4k views

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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0answers
30 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 ...
0
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3answers
49 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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0answers
24 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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1answer
137 views

Capacitance of short length transmission lines

I would like to simulate a short length transmission line in MATLAB/Simulink. In the library, there is a block that simulates a transmission line. The parameters that are required are the resistance R,...
3
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2answers
20k views

When can I use the formula P=V^2/R?

I'm currently learning about the transportation of electrical energy through power lines. I now know that transporting current at a very high voltage cause minimal power loss compared to transporting ...
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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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0answers
53 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 ...
38
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8answers
10k views

Why do utility companies supply at a frequency of either 50/60 Hz?

It just struck me that Utility Companies world-wide supply domestic users at either 50/60Hz. It could have been selected to be 10 Hz, or 100 Hz ... whatever Was 50/60 chosen at random? Is there some ...
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0answers
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
50 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 ...
31
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6answers
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 ...
3
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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
55 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
985 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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0answers
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 ...
0
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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 ...
12
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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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2answers
304 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 ...
1
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1answer
118 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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1answer
507 views

Do fiber optics make any noise/sound that can be heard by the human ear?

In regards to, "...the noise sources in a fiber optic link include noise from the RF amplifiers in the transmitter, the laser diode, the photodiode and RF amplifiers in the receiver. Of which laser ...
5
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2answers
189 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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0answers
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 ...
11
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2answers
4k views

When a wind turbine does not produce enough electricity how does the power company compensate for the loss?

I heard once that when a wind turbine power plant doesn't produce enough electricity the power companies are sometimes forced to turn on a couple of jet engines in order to compensate for the loss, is ...
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0answers
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 ...
2
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3answers
217 views

Off grid LED solar lighting without batteries

I have 2 COB LEDs (12-14V DC, 50W, I think with 3,75 A in data sheet). I need to run them with a solar panel, it should only run when there is sunlight no batteries needed. Using a 270W panel (open ...
3
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1answer
183 views

What is the purpose of these PTs?

What is the purpose of these PTs installed on the two coupled busbars? And we have whole panels in the HV room for these PTs. Kindly explain. (Photo attached)
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2answers
275 views

A confusion about radial schemes in power distribution

My lecture notes about distribution systems/radial schemes say the following: •In this scheme, feeders radiate from a substation in all directions and feed distributors at one end only. • SA is the ...
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2answers
539 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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