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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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 ...
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3k 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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86 views

How can i record the rpm of a small spinning object with out the use of a hand held tool such as a laser.

How do I measure the revolutions of a moving object as it rotates around. Imagine a fan blade, I need to measure the rpm of the fan without using an outside tool such as a laser rpm reader. Ideally ...
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1answer
247 views

dq0 Transformation Interpretation

What is the physical interpretation of dq0 axis transformation in electrical machines and power systems? How does this transformation helps? Thanks
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74 views

What will be Resistance for maximum Power transfer from network A to network B?

simulate this circuit – Schematic created using CircuitLab Can we apply Maximum Power transfer theorem if we are given two networks both with voltage sources. In solution it was said that for ...
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1answer
45 views

How much power can transit through a power line linking generation and load?

First things first I am not an electrical engineer at all so please bear that in mind when you reply/comment. I am looking at the following problem, I have a power line which connects a windfarm to a ...
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1answer
64 views

Assemble Peltier Cooler to Li-poly Rc Battery

I have procured a thermoelectric cooler (TEC, this one) and my purpose of the TEC is to produce current for the Li-poly RC battery to increase its battery life. The Li-poly RC battery has 7.4V stated ...
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1answer
49 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,...
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1answer
549 views

Why is a short circuit in the secondary winding of a transformer reflected on the primary side?

I was reading this answer and I would like to understand why if the secondary is short circuited the primary winding will also reflect the short circuit despite the fact that they are isolated. Would ...
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1answer
73 views

How is the inverter connected to the grid?

I just finished circuit designing of an inverter which converts 440V DC to 230V AC. Now my manager asked me what kind of connectivity does it has. I answered him: "The current connectivity is AC as ...
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1answer
33 views

Low voltage grid frequency with renewable feed-in

If a low voltage grid's consumption equals to that grids renewable energy production, does it mean the transformator basically does nothing, like an open circuit? Are grid-tied inverters (smart) ...
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1answer
217 views

The critical clearing time (CCT) of a fault in DIgSILENT

How can I determine the critical clearing time (CCT) of a fault in DIgSILENT? How can I use DPL to determine the critical clearing time (CCT) of a fault in DIgSILENT?
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99 views

Shorten the mini Christmas light strand

I need to shorten a 100 light strand of mini lights to just 18 lights. Based on the wiring, I believe the strand is engineered as two 50 light strands in parallel. The strand is rated for 120 V and ...
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1answer
116 views

OP AMP DESIGN - The first bit is fine

Hello guys, can you help me with the second bit of the question? I found the first two answers ... I proved that vo = 2(v2-v1) and r = 800ohms ... but with for the second bit I got stuck in an ...
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1answer
59 views

Coordinated relay tripping for Protection in Modern Power System

I have been working on Etap Software to understand the basic protection scheme using Current Transformer, circuit breaker and Relays. But i am having trouble in the coordination of the tripping in the ...
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0answers
30 views

Startup and auxiliary/station transformer power parallel to bus

This question is in regard to switchyard/electrical distribution operations in a utility power plant. During a startup, the electric distribution system is lined up so that the startup transformers ...
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0answers
2k views

How to calculate the earth fault current in a transmission system with no ground wire?

Background information, and my thought on the matter are provided in the end of the question. I need to calculate the fault current in case a fault occur for instance 10 km away from a transformer ...
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0answers
23 views

What does 'Rectifier Loading Effect and Loading Factor' mean

I came across the terms 'Rectifier Loading Effect' and 'Rectifier Loading Factor' when reading IEEE Std 421.5-2005 Recommended Model for Power Stability Studies, mentioned in those ACxA models. What ...
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0answers
109 views

Use of 3 phase transformers which are ∆-Y connected and Y-∆ connected

Different literatures say different things regarding ∆-Y and Y-∆ 3 phase transformer connection... Some say that ∆-Y is used for step down and Y-∆ is used for step up while others say just the ...
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0answers
378 views

Power distribution boards - hierarchical numbering system

I wish to renumber the circuit breakers (and possibly the cables) in an industrial plant. Numbering should give a unique identifier for each breaker. Numbering should give a path back to the incoming ...
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0answers
141 views

Determining VA rating of the small transformers

I have a 1000VA toroid transformer which weighs 8 Kg. Based on this power-to-weight ratio, can I conclude that another transformer which is EI cored and weighs 7 Kg must be 875VA? Or such ratiometrics ...
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0answers
488 views

What is Virtual Array Antenna?

What is virtual array antenna (VAA)? I have searched it everywhere but i was unable to find direct answer to this question. I know this concept was built from phased array antenna. Please explain ...
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0answers
3k views

What is a Thyristor Switched Series Capacitor (TSSC)?

I'm struggling to understand the physical difference between the Thyristor Switched Series Capacitor (TSSC) and the Thyristor Controlled Series Capacitor (TCSC). From this book, I understand that a ...
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21 views

How to model P, V variations in PV buses in a load flow problem?

I'm trying to use the DC power flow results as a base, and modify it to approximate AC power flow results more accurately. So far, I have been able to do that in a few simple test cases from Matpower, ...
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31 views

How to have Wye-connected Potential Transformers(PTs) and Neutral Ground Resistor short circuit detection at my ground fault protection relay?

Detecting if the Neutral Ground Resistor (NGR) is shorted is something that must be checked at the Ground Fault Protecting Relay. The typical way to do this is to inject a DC component and to measure ...
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103 views

Trapezoidal Rule of Complex RLC Circuit using MATLAB

I am having difficulty trying to figure out how to solve this circuit using the trapezoidal rule. I know how to do so in a first and second order RLC circuit however this particular circuit is giving ...
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27 views

Power Outages and Surges

I live in South Africa where we experience frequent power outages due to so-called "loadshedding". With this, there have been numerous cases of damage to appliances due to surges, usually when power ...
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61 views

Transmission Line Voltage Terminology Confusion (Very Basic)

I have a issue interpreting what transmission line voltage actually means (I have tried researching but nothing clearly explains in detail, just says its a 110kV line etc).For example if i have a ...
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0answers
65 views

Smart grid communications

For my final project, I am looking about smart grid. What I want to know is that what kind of communication is done in smart grid and the appliances, protocols used etc. Can I extract a data whether ...
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0answers
66 views

To what extent are semiconductors used in high voltage and power grid electronics?

I'm thinking of silicon controlled rectifiers and HV thyristors. Why have vacuum tubes been phased out or have they? I believe that in some countries, power grid electronics is entirely tube-based ...
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32 views

Black body heat to current conversion

I have learnt about Seebeck effect and peltier effect in college physics, but it was more of theory than hands on numbers and practicals. Now is there a commercial or DIY module that can produce ...