# 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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### 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 ...
49 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 ...
46 views

### 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 ...
35 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- ...
68 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 ...
35 views

### SCC for Synchronous Generator Using Matlab

What should I put in ''Three-Phase Programmable Voltage Source'' block ?
36 views

### 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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### AVR Excitation System and Generator in SimuLink

I am designing in simulink cooperation of synchronous machines with the grid. The main blocks are Excitation System which is AVR [link1] and Synchronous Machine [link2]. On the site we can find "...
78 views

### Understanding of torque constant and efficiency of a permanent magnet motor from datasheet

I am trying to understand the efficiency of the following permanent magnet synchronous motor Motor Datasheet (note we are using the medium voltage model), and its relationship with the input voltages ...
593 views

### Meaning of motor constants for three-phase PMSM

When looking at three-phase permanent magnet synchronous (brushless) motors, $K_T$ and $K_V$ numbers are often specified. Also, controllers for these motors typically specify maximum currents. ...
33 views

### Is the orthogonal spacing of dq axis of AC motor with respect to electrical or mechanical angle?

In FOC of AC machines, we try to align the stator flux to Q axis and maximize the value. The idea behind this logic is when rotor flux and stator flux are orthogonal, we generate max flux. But is the ...
18 views

### picture of dq axis in multi pole motor

How does the dq axis of multi pole motor look like? Typically online images search show dq axis for motor with one pole. Consider a 4 pole stator PMSM motor. Will there be multiple dq axis for each ...
61 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 ...
82 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 ...
303 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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### 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 "...
27 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 ...
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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### 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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### 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 ...
42 views

### 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 ...
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 ...
35 views

### 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 ...
378 views

### What happens to the Real and Reactive power when I increase the excitation current in a 3-Phase Synchronous Generator?

Basically my doubt is, for the same load, why does the Real power remain constant when I increase the excitation current?
25 views

### Mean Free Path of Magnetic Core

I don't understand how they got the mean free paths (ls) of each leg. I know that I should be calculating the longest + the shortest paths and divide them by two, but I don't know HOW I should be ...
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### Can torque angle of motor be positive?

For any motor text say that, the rotor field follows the stator field with a certain torque angle. And in case of generator, the stator field follows the rotor field with a negative load angle. The ...
104 views

### EMF - DC Permanent Magnet Motor

I am using FEMM to design a dc permanent magnet rotor. I am trying to calculate the EMF that is induced to the rotor. Since each coil has a different position, the induced emf will be different. In ...
76 views

### What is these factor multiplying the current of the copper wires_?

I was reading some solved problems about transformers but I don’t understand how was calculated the losses in the copper. - Enunciate: A one phase, 10kVA, 2400/240, 60Hz distribution transformer has ...
45 views

### Transformer equivalent circuit values

I was given the following data about a transformer 1 $\phi$ 25 kVA 220/440 60Hz gave the following test results Open circuit test (440V side open) 220 V, 9.5 A, 650 W Short circuit test(220V ...
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### VI curve varistor and compere between varistor and arrestor

why we need to connect arrestor in parallel with varistor in some circuit ? and we know both is work to protect against high voltage? like this pic.
184 views

### Induction generator

I have an induction generator on the same shaft with induction motor. Both machines are same (have same nameplate: $U=400\,V$, $f=50\,Hz$, $n=1435\, rpm$, $P=9.3\,kW$, $\cos(\phi) = 0.90$...
144 views

### Disconnecting the load from a synchronous generator

How is the terminal voltage of a synchronous generator affected when we disconnect the load ?
59 views

### Motor Flux in Wb

I'm trying to simulate a squirrel cage motor using asynchronous machine SI units in simulink The problem is when I view stator Flux(both q and d) its unit is in V.s (volt second which is used for ...
69 views

### Transformer Leakage Inductance and power factor

How does transformer leakage impedance affect power factor? Or how does the X/R ratio of the transformer change the power factor ?
47 views

### Generating Electricity: Stator Help

I am trying to prototype an electricity generation stator with a magnet in the center. I have zero background in any of this but I have an interesting idea that likely has not been done before and yes ...
248 views

### mmf distribution in rotating electrical machines

we have known in ABC sequence in three phase system,phaseA leads phaseB by 120 electrical degrees, but in mmf vector of electrical machines,mmf vector of phaseB leads mmf vector of phaseA by 120 ...