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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29 views

Giving back to the grid [closed]

I'm wondering about sending electricity back into the grid. If I had a green energy source the was ac. What volts and Amps would I need to send that back into the grid? And what equipment would I need ...
76 views

How to increase current by reducing voltage? [closed]

I have a 400kv HV generator of 500 mA , but I want to increase the current by 10 time or more by reducing less voltage as possible/sufficient , help
63 views

Terminology: Proper way to denote typical European 3-phase AC grid

The widely known 3-phase grid in Europe with 50 Hz and 400 V between two phases and 230 V between each phase and neutral is often referred to as "3 x 400 V" or "3 x 230 V". Is one ...
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2k views

Would reducing the air gap between the rotor and stator to micrometer/nanometer scale distance proportionately increase a motor's power?

I'm asking this because the smaller the distances between electromagnets, the stronger the electromagnetic field. I don't know if this would mean a proportional increase in power, be it either torque ...
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1 vote
99 views

Reactive power calculation: what did I do wrong?

I calculated the question and I did not get the same answer as in the book. Could someone please explain why my method is not correct? Question: My solution: Book solution: The problem is from the ...
1 vote
54 views

Why does disconnecting the receiving end of a transmission from the sending end increase the voltage at the receiving end? [closed]

Some background information: I have a transmission line circuit (included below). The rated voltage is 63.639kV and the rated current is 325A. The characteristic impedance is 30.3 Ohms. I also have ...
108 views

IEEE 34-Bus Radial Distribution Test System

Whenever I look up IEEE 34-bus test systems, the following images are what is presented. I often find the first image in papers related to optimal capacitor studies, the second image I find in any ...
234 views

What is the highest voltage currently in use for power transmission?

This is merely a question of idle curiosity that I hit a dead-end trying to research. While the Ekibastuz-Kokshetau high-voltage transmission line famously[citation needed] holds the record for ...
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366 views

Why are transmission lines typically 115, 230, or 500 kV?

Is there a historical or technical reason why US high-voltage transmission lines are typically 115, 230, or 500 kV? (ref). These seem like semi-random numbers. I found that 115 kV goes back to 1917 at ...
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1 vote
245 views

Is this Medium Voltage Distribution Delta or WYE

You have been extremely helpful before on a few things. I have another question. This is involves medium voltage 15 kV AC 3 phase distribution 3 conductor plus ground, shielded cable. Braided/twisted ...
74 views

Closed-loop Transfer Function [closed]

help me answer this. pls show me your solutions, that would be very helpful so i can understand how you did it.
1 vote
163 views

What information can be discerned about street-side power transformers just by looking at them?

I am new, and delighted, to be part of this stack. I was just wondering from the two images of power transformers shown below what specifications can be gleaned from their outward appearance alone? ...
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1 vote
44 views

Facing issues while trying to measure high voltage at high frequency [closed]

In the attached circuit I am facing a strange issue. I am trying to measure the voltage across the spark gaps 1 and 2 which are about 1 and 2mm. To do that, I have made a simple led chain indicator (...
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Question related to damping, quality factor and natural frequency of the system

If the G(S) is as follows: Then how would you calculate the value of undamped natural frequency, damping factor, and quality factor of the system?
41 views

Does SPI Configuration Persist After DRV8873 Power-Off?

I am designing board to drive BDC motors using a DRV8908-Q1. Here is the data sheet. DataSheet I would like to inquire if SPI config persists (not go back to DEFAULT) after the driver is powered-off.
1 vote
103 views

Why are high-voltage circuit breakers not automated? [closed]

I came across a video from Ontario Power Generation about them using a fancy Boston Dynamics robot to trip a high-voltage circuit breaker because it’s too dangerous to do it manually. I was interested ...
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In an ETAP simulation, why do I get different tripping sequences depending on whether I simulate a short-circuit before or after a specific CT?

I have a simulation of a relatively simple power system on ETAP. Relays are selective with each other in the Star view, however when I simulate a short circuit, the sequence of tripping that I get ...
474 views

How are CCA's (Cold Cranking Amps) measured, specifically with regard to the load resistance?

I'm not interested in the "cold" part of CCA's. Here is my understanding: The electrical system draws (by far) the most power during the actual start-up of the engine. The idea (more or ...
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1k views

What are these circular basket-like structures on a high voltage transformer's insulators?

Wikimedia commons contains this public-domain image of a high-voltage transformer of the Tarza power plant in Iraq, taken by Marvin Daniels in the U.S. Army: There is much I do not immediately ...
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89 views

How and where to learn protective relaying for power systems?

I'm trying to learn protective relaying for power systems. More specifically, I want to learn how to calculate the settings that must be configured in the digital relays in order to build ANSI device ...
38 views

Where can I find synchronous machine datasheet?

In the laboratory where I work, we have developed our own MATLAB library for simulating transient response of power systems, and I am currently working on some simulations of IEEE 9 bus system. I was ...
97 views

Conversion from DQ0 to dq0 and vice-versa

I have been working with multi-machine power systems, and I have been struggling with the transformation between the dq0 and DQ0 frames. I will first introduce my understanding of these frames, and ...
494 views

How a 3-phase system delivers more power?

In a 3-phase system, when one phase hits the peak and is about to go down, the next phase starts hitting the peak, and there would be a total of six peaks as compared to two for a single phase system (...
1 vote
72 views

Is it difficult to join two modern power grids? [closed]

I understand the voltage, frequency, phase, and maybe power quality of each grid must all be compatible at the moment of linking, and that each grid is a complex beast that's difficult to influence. ...
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22k views

How to ramp up a factory consuming a lot of energy?

Can you please explain how to manage the process of ramping up a factory with a big electric consumption? I am wondering how it is possible to balance the grid during the start up phase of a big power ...
607 views

Photovoltaic generated power: Why is my PV system selling back to the grid while at the same time it is consuming energy from the grid? [closed]

I've noticed on my power bill that there are times during the day when my PV system is selling power back to the grid, while at the same time, I am consuming from the grid (see screenshot below). That ...
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286 views

Busbar short circuit rating vs. cubicle rating

First: This question is about medium and high voltage switchgear, not electronics. A 7,2 kV switchgear has a short circuit current rating of Ik = 40kA/3 s. The ...
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81 views

Simple way to achieve constant output current from a boost converter for battery charging in an EV penetration simulation study using EMTP simulation

I am simulating Level 1 and Level 2 EV chargers to test the impact of such chargers on a grid in a developing country. I am simulating in EMTP-RV (software for simulation and analysis of power systems)...
70 views

What are the highest permissible current harmonics input to the grid?

I'm in the process of completing my Master Thesis and I need to model the current harmonics input of large-scale PV plant into the grid. We're talking about 100MW connected to the 110kV line, using ...
25 views

Solving an AC Circuit Inverter Estimate

This is an electric power engineering question not electronic so this circuit doesn't actually solve. I added it for illustration purposes. Srate = Sout. I'm trying to solve this below circuit for Vg ...
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Does a control panel that will start/stop two pumps require its own circuit protection?

Does a control panel used to start/stop two pumps require circuit protection for the main 208V feeder lines if those lines are already protected at the main panel in a separate room? The main panel ...
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1 vote
211 views

What is Vac(peak) in this question?

Bit confused at what Vm/Vac(peak) is. Either 230V or 325V. rest seems simple
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1 vote
78 views

Consider a long transmission line (4 km). Its a single conductor line with the inner conductor insulated. The outer shell is steel ground. Consider two scenarios. Scenario A: 120 V DC power supply, ...
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EV charger power distribution in an apartment complex

I am on the executive committee for an apartment complex. We have had a number of requests from residents to add EV chargers to the basement carpark. It's obvious that the number of these requests ...
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1 vote
89 views

Disappearing voltage [closed]

I'm an 30 yr electrician. I have a problem neither I nor my co workers have ever seen nor can we find an answer to. Here's the situation. In a particular 60' length of EMT, (metallic conduit), we had ...
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90 views

Power and energy of pumped hydro versus grid scale batteries

A company is proposing a pumped hydro system where they state on their website as “capable of producing up to 335 MW of electricity with around 8 hours storage”. The same company is proposing a ...
204 views

What are these jumpers between phases and earth in a residential distribution grid?

In my city, in quite a few locations there appear to be wire jumpers from each phase to the earth(?) wire. They appear to have ceramic insulators, so I suspect they aren't just directly connecting ...
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430 views

Resistor That is neither Series or Parallel

My textbook says that the 5Ω and 2Ω resistor are neither in series or parallel. My understanding of the reasoning is that the current from the 5Ω resistor has two pathways it can travel - either to ...
1 vote
67 views

Decoupling tri-state power

There is a power supply BAT1 that provides +5 V power (the schematic shows 9 V, but it's providing 5 V): After a certain period of time it shuts down, leaving its output in a strange tri-state (or ...
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For Delta-Wye transformers, with neither side grounded, can one get electrocuted by standing on earth and touching one of the Delta side wires?

It seems to me that there is no path to ground in this case. So, the voltage on the Delta-side of the transformer cannot drive a current through the ground (ie, through the one touching the wire), ...
395 views

How do grid tie inverters sense the mains phase and quality and at the same time feed current into it?

Grid-tie inverters synchronize the phase and also check the quality (frequency, magnitude) and shutdown in case of errors to prevent what's called islanding, i.e. to prevent feeding current to network ...
3k views

How does a solar / PV inverter get preference over grid source for the house load?

I've got a solar PV inverter and grid feed supplying the house. They are both connected (via their respective circuit breakers) before the switchboard, so from the junction to the house switchboard it'...
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267 views

Correct use of circuit breaker before/after 220-24 converters in distribution board

Say I have a distribution board where 220VAC comes in and goes into a 220VAC-24DC converter. 24V DC is subsequently fed into a KNX-driven RGBW dimmer which powers a LED strip directly along a 5x1.5 ...
90 views

Wind turbine power characteristic

The following graph was obtained using the MATLAB Doubly-Fed Induction Generator (DFIG) wind turbine model. I'm confused about why spikes occur at the points A to B and C to D. If you have any ...
231 views

How do power grid operators regulate the power flowing through their networks?

My question: How do grid and transmission line operators regulate the amount of power flowing in their networks, both to utilize the network optimally and to enact delivery policies like those in the ...
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The voltage created in the transformer

The voltage generated in the transformer must be due to the change in the flux in the coils, but if the voltage is DC, why is no voltage induced? Of course, we know that voltage is created by the ...
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Cost of pin insulators

H. Cotton's Transmission and Distribution of Electrical Energy states that the cost of pin insulators increases exponentially with voltage. Why is this, and why isn't it linear?
828 views

How many winding turns in a HV power transformer?

I'm creating a simplified 2D model of 3 three-winding 132/22 kV, 40 MVA transformers that I'll use to calculate the magnetic field surrounding them. Now, the turn ratio is of course 132/22, but is ...
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