Questions tagged [electric-machine]

Electrical Machines are Electro-Mechanical energy converters. They maybe classified into motors (electrical -> mechanical) and generators (mechanical -> electrical).

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31 views

DC Motor power diminishes quickly

I have an n20 DC motor which has a gearbox with a 55mm m4 threaded shaft (see image below for visualization of the motor). I'm compressing a spring with this motor, so the motor needs to work ...
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Do you know an electrical power system drawing software? [closed]

I would like to draw three phase circuits with short circuiting some phases. Can you recommend an easy to learn software to do so?
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31 views

Is the zero sequence component considered balanced?

how is the zero sequence component is balanced while the three vectors are inphase and not displaced from each other by 120°? Isn't the definition of a balanced system is one in which the magnitudes ...
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29 views

Zero sequence component in unbalanced faults rotation

I am trying to understand the physical/practical meaning of the zero sequence component, I referred to some books. however, I am not sure is me or are there different interpretation of the zero ...
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1answer
73 views

Diagram of electrostatic precipitator

I was reading an article about working of ESP at this website: https://www.electrical4u.com/electrostatic-precipitator/ Though the explanation was nice, I couldn't understand what the diagram conveys....
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Armature and terminal voltages in DC machines

In the below page I am trying to grasp the way the terminal voltage and armature voltage are related to each other. Below is my attempt to understand their relation: Do you agree with my ...
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Motor vector control and parameters estimation

Vector control methods require good estimation of magnetic flux. In Direct Torque Control it would vector of stator flux. In order to estimate it properly one has to know motor parameters such as ...
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37 views

Steady State speed of rotor in following doubly excited system

I'm trying to analyse following system - A three phase armature winding on stator and on rotor field winding and both stator and rotor are cylindrical . And armature winding is connected to a three ...
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57 views

Induced voltage in the rotor of the induction motor

Given that the resultant mmf wave in the air gap of the three phase two pole induction motor is $$F(\theta , t) = \frac{3}{2}NI_m \cos(\omega t - \theta) \tag{1}$$ what's the value of the induced ...
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54 views

Voltage build up in induction generator and its working principle

I had some doubts while reading about working of self excited isolated induction generator . If principle of operation of self excited isolated induction generator is similar (in a sense that in ...
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2answers
49 views

How to predict which machine will act as motor or generator in Hopkinson's test?

Is there any way to predict which machine will act as a motor and which acts as a generator before applying the supply voltage? I cannot find a way to predict what will be the behaviour(motor or ...
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3answers
289 views

Starting torque of series vs shunt DC motors

Recently, I read that starting torque of series motors are much higher than shunt motors. I try to find out what is reason behind it and I get to know that this is because in DC series motor torque is ...
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1answer
49 views

Confusion in magnetic neutral plane of DC machine

I was reading book Electric Machinery by Chapman and in topic 'Armature reaction ' It is written that "The magnetic neutral plane is defined as the plane within the machine where the velocity of ...
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2answers
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Behaviour of flux in DC motor

In given figure if we assume both sides (up and down) with equal number of coil turns (N each). And we wound(which generally we do in DC motor) coils such that they create flux and form a North-South ...
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35 views

Analysis of three phase star star connected transformer

What is going on this circuit(below) and what would be current measured by ammeter(zero or non zero)? Description- These two transformers winding are star star connected and a balance sinusoidal ...
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34 views

3rd harmonic component of flux and current in Star -Star connected 3phase transformer

I wanted to understand what will be 3rd harmonic component of flux and current in following connection . Connection - Star- Star connection (with neutral on primary side only) Further description- ...
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3answers
376 views

Voltage and current rating of electrical systems

Why voltage and current ratings of almost all electrical systems are RMS value of voltage and current not peak value of voltage and current? First I thought maybe because mostly ac input is sinusoidal ...
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2answers
68 views

Contradiction in solution for ideal transformer

I was trying to analyse an ideal transformer with one ideal independent voltage source on each winding. I got a relationship between those voltage sources but it contradicts the fact that both voltage ...
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57 views

How to set solver for control loop simulation?

I have been developing a simulation of the field oriented control of the three phase squirrel cage induction motor (control is oriented by the rotor flux). I have been using the Xcos which is an ...
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159 views

3 phase transformer efficiency calculation

This is an assignment. No matter how hard I try the answer is never what I expect. Here is the question: Three single phase transformers, each rated at 12 kVA, 120/240V, 60Hz, are connected to form a ...
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42 views

Why does wave winding not need a voltage equalizer?

I understand that lap winding needs a voltage equalizer to balance the voltage at different points. However, I could not understand why wave winding does not need one (according to the textbook "...
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45 views

Why duplex lap winding has twice as many current paths as simplex lap winding?

I found the statement of question on page 346 in the book "Electric Machinery Fundamentals, fifth edition" written by Stephen J. Chapman. When I searched for how duplex lap winding looks ...
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1answer
37 views

Explanation of v curve of sync machine

I am trying to understand the v curve of synchronous machine. Particularly, the point that changing field current can put the machine in leading or lagging mode. I am trying to get an explanation to ...
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2answers
129 views

Unexpected behavior of the Luenberger observer for three phase induction motor

I have been developing control software for three phase induction motor. The control software will implement the field oriented control algorithm. The considered algorithm is oriented to the rotor ...
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1answer
43 views

What electrode material can I use for electrical discharge machining? [closed]

Can I use an electrode made of melted soldering wire in electrical discharge machining (EDM) instead of copper or graphite? I think it is very easy for me to make electrode by using melted soldering ...
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what does nominal numbers of electrical machines mean

I got confused about rated numbers of generators and motors like rated voltage and rated power . I know nominal numbers of electrical machines are numbers which the machine is designed to operate but ...
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71 views

How to find rated voltage of a machine?

I am trying to understand what a rated voltage/current/power mean for a machine. when I google it, I typically get information on how to find it from nameplate, but I am trying to understand it ...
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184 views

What are the two sensors doing in the automatic bread production line? [closed]

I want to know what is the name of these 2 sensors and what function they perform Some of you were complaining about the picture quality. It is the highest quality image I can get. Also these sensors ...
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25 views

How to determine transform angle in field oriented control of three phase induction motor

I have been developing a control software for the field oriented control of the three phase induction motor. I have studied a lot of application notes and literature about this topic. Based on that I ...
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58 views

Rotor Current and Torque Producing Current in Induction Motor

Is rotor current of an Induction motor always same with torque producing current? In torque equation of Induction motor, there is also one factor called rotor power factor. if rotor current and torque ...
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1answer
48 views

Why stationary armature is preferred for commercial use

While reading a book on electrical machines, I found a point that says that for power generation, a stationary armature is the preferred type. If in any generator, there must be moving parts, why is ...
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2answers
39 views

Difference between reactive load and source?

Probably a silly question, but I am coming across terms like reactive power load and reactive power source in some articles in web. Does it matter if a reactive component is a source or load? Say ...
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26 views

Moment calculation for DC serial generator question

DC serial generator tag information : 9.25kW, 185V, 1500rpm . this is the table I have two solutions, which one might be right
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44 views

How can I find current in this Ward-Leonard system?

I was able to find only RPM in this question. How can I find the armature current?
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101 views

Transformer at no load [duplicate]

I have been reading about the working of transformers at "no load" condition, that is when no load is connected to secondary side of the transformer. I don't understand why the transformer still draws ...
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2answers
346 views

How does this old fan regulator circuit work?

I was on the lookout for an old fan regulator. I had heard that its power consumption was constant at all speeds. I could lay my hands on this 1970 regulator. It appears to be a transformer with ...
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1answer
114 views

Torque production in PMSM

First and foremost I have a question regarding the MMF distribution in a Motor produced by a single coil. I found a picture here: Why does the MMF not start at 0 at 0°? When I apply the $$NI=\int{H \...
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26 views

DC series machine

What is the different between electrical and mechanical torque? and How to find the mechanical torque if electrical torque is given?
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263 views

How was ceiling fan speed controlled before the invention (or availability) of Triac?

I am interested to know about the circuit diagram of the ceiling fan regulators of the old days (when Triacs were not available). I have searched on google but all of the results were related to SCR. ...
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33 views

SCC for Synchronous Generator Using Matlab

What should I put in ''Three-Phase Programmable Voltage Source'' block ?
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1answer
129 views

Induction motor starting torque and pull out torque

Recently I was doing some work on the induction motor where I found some general theory on starting speed torque curve of the induction motor. Where the theory is the starting torque will be 1.5x of ...
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167 views

What is meant by AT/cm in transformer?

In a problem related to transformer loss I have found a line "AT/cm for a flux density of 1.2 Wb/m^2 in iron to be 5" I've searched in google for 30 minutes about what is AT and how it is related to ...
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25 views

Formula for calculating the MMF and its harmonics of n-Phase PMSM with integral slot winding (slot per pole per phase =1 & 2)?

Data\Prerequisites: Integral slot winding full pitch winding Slot per pole per phase = 1 and 2 (two different possibilities) Number of phases : n = 3,4,5,6,7 Assume number of turns = N and current to ...
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What is all properties of orthogonal axis (dq) axis?

We know about the transformation between abc three phase to dq0 axis which is orthogonal. BUT I am confused about What is the added value and all properties of orthogonality for dq0 axis that help in ...
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419 views

Why do some motors have high rpm while other have low even though having same power consumption

I have seen a 500w motor which run on 1200 rpm but a 300w motor with over 10000rpm . I know using a gearbox can give required rpm or torque and torque is inversely proportion to speed but how can I ...
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In 1965 when Ivan Sutherland was testing the Vr machine, what was he viewing in the headset

Ivan Sutherland is an american inventor who invented virtual reality and the sketch, they recorded a video 55 years ago about him experiencing the headset, I always wondered what was he actually ...
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Voltage Difference Between Machine Laminations

Given a lamination stack that is exposed to a transient magnetic field, how can the potential difference between the individual laminations be determined? is there a rough rule of thumb that can be ...
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Does regenerative braking, using supercapacitors, really save fuel in the case of diesel city buses? [closed]

Does regenerative braking, using supercapacitors, really save fuel in the case of diesel city buses? A 10-ton diesel bus, fully loaded, that slows down, on average, from 30 km/h to 0 km/h each ...
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31 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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When do the positive sequence negative sequence, and zero sequence apprea?

I have analyzed three phases current in different cases, but I am still confused about some cases. Positive and Negative sequences are appeared but not the zero. Zero sequences is appeared, while ...

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