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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1answer
38 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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2answers
79 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
165 views

How does this old fan regulator circuit work?

I was looking for an old fan regulator for a long timebecause a lot of people said that the power consumption of it was the same at high speed and low speed. This is a 50 year old fan regulator (...
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1answer
67 views
+50

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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1answer
24 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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3answers
166 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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1answer
29 views

SCC for Synchronous Generator Using Matlab

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

the change in the magnetic permeability of a magnetic substance

Using an equivalent magnetic circuit, explain the change in the magnetic permeability of a magnetic substance when the applied current is 30A. condition-The magnetic flux is 250 wb when the applied ...
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1answer
29 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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2answers
59 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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0answers
18 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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1answer
21 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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2answers
102 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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37 views

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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1answer
37 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 ...
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2answers
158 views

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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1answer
27 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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0answers
30 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 ...
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1answer
99 views

Can someone tell me what this machine is? [closed]

It has two probes on two cables. I think it might be an xray machine but I can not be sure since there is no readable info on it. Can someone please identify it?
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1answer
170 views

Tesla model 3 motor

The Tesla's model 3 uses IPM-SRM motor in the rear drive. This motor is fed by AC supply OR DC supply? Is the motor's stator is of salient pole construction OR the same stator as of the induction ...
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1answer
106 views

Why earth pin in plug is larger than the other pin?

Why main line pin is not bigger ,the work of main line pin is more important than earth line? And the flow of electricity is also pass through main line and neutral pin then why earth pin is larger ...
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2answers
325 views

Why are the poles of the stator and rotor taken differently in the picture below?

The rotor and stator in the picture below have the same orientation of flux lines yet the are taken as opposite that is flux lines leaving the stator is taken as a South Pole while flux lines leaving ...
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1answer
62 views

Are the emissions to power electric cars really better for the environment than the emissions from petrol cars? [closed]

In my country most of the electricity is generated by coal which is then in turn used to power electric cars, which I don’t think is to good for the atmosphere, is there any prof that this is better ...
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1answer
115 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?
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1answer
101 views

Are permanent-magnet motors equally (in)efficient as motors vs. as generators?

Given a permanent-magnet motor with an efficiency of 80% that converts 100W electrical input power into 80W mechanical output power, would the motor have the same efficiency if used as a generator? ...
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0answers
40 views

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 "...
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2answers
62 views

In 3 phase induction motor how many phase will be generated in wound type and squirrel cage rotor?

In 3 phase induction motor how many phase will be generated in wound type and squirrel cage rotor? If we consider a generator when the rotor rotates there will be voltage induced in every pole of ...
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1answer
46 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 ...
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1answer
212 views

How brush shifting affects current distribution in dc machines?

I understand that how armature reaction causes neutral plane to shift by some angle . If brushes are placed along Geometrical Neutral Axis, then there'd be sparking during commutation as voltage ...
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1answer
22 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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3answers
2k views

If a high rpm motor is run at lower rpm, will it produce more torque?

I did the following calculations: Max current = 1.2A, Max voltage = 12V Then power = 14.4 watts = 0.019hp Rpm = HP * 5252 ÷ torque I need a torque to 2kgf-cm = 0.144 lb-ft Gives rpm= 698. Thus this ...
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1answer
98 views

why induction motor torque oscillating?

why when start induction motor the torque oscillate before become constant, like the following matlab torque simulation graph .
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0answers
25 views

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 ...
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2answers
150 views

Hidrogen generator - electric problem

I made an Hidrogen generator (HHO) like YouTube : https://m.youtube.com/watch?v=zq8YMON9hjA&list=PLPCtNZjqSVUhWVzuxEkzlyrz1CatH8OiF&index=29&t=504s but , it does not working at all. ...
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2answers
104 views

Automotive alternator

I have been working on a project where so called Lundell alternator plays a crucial role. I haven't got any experience with this device sofar so I have decided to study some literature regarding this ...
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2answers
60 views

Electric brushed motor for electric car project

I am using a 24v 11amp 5700 rpm motor for a single seater car project. The problem is that when i am connecting the motor directly to the batteries without any throttle or control the vehicle shaft ...
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1answer
55 views

Sources and References for Motor Selection [closed]

So, I was wondering if there is a book/textbook which discusses the issue of selecting the proper motor for a job. The type of it (induction, synchronous, DC, etc.) and mainly the nominal power of it. ...
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1answer
49 views

Power consumption for an in-wheel motor

I'm trying to estimate the power consumption of an in-wheel electric motor. I used the formula $$P = T\cdot\omega + K_m\cdot T^2$$ where T is the torque, ω is the motor angular velocity and \$...
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1answer
993 views

Will an AC series motor work with DC supply?

I have read that a DC series motor can be operated using AC supply, but there will be excessive heating in the core and yoke and also a low power factor. So, construction is modified to have laminated ...
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5answers
3k views

How do I fix the speed of a generator?

If I need to generate power at a specified frequency, then I need to make sure that the rotor of the generator rotates at a specified speed (rpm). But when I am rotating it with steam or water how do ...
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1answer
143 views

Generator Frequency

How do I calculate the kW output on a generator when changing from 60Hz to 50Hz? i.e. if I have a 70kVA generator at 60Hz producing 56kW, how do I calculate what the kVA and kW's would be if I ...
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2answers
560 views

Do resistors consume reactive power?

I encountered this problem in one of my books where the problem asked to find the power loss in the core of an induction motor. I worked through the problem and I found the current as in the picture, ...
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2answers
284 views

How is the shaft of a motor fixed in its position?

Consider for example a brushed DC motor. 1- Is the shaft of the motor (which is rotor in this case), actually floating mid-air because of magnetic field of stator? Why doesn't it fall down due to ...
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1answer
2k views

Why does a wind turbine deliver reactive power to the grid during no winds or when turbine is stopped?

An answer to a previous question explained that a turbine in stop mode may deliver reactive power to the grid. It also takes active power from the grid to run its control system, lighting system and ...
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2answers
376 views

How do designers know about kilowatt power of wind turbine generators like 1.5 MW?

Generators and transformers are always designed in kVA because designers never know about the load it will provide power to. Then how do we know the wind turbine generator will deliver 1500 kW or 2 MW ...
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2answers
326 views

What is torque-ampere ratio at electric machines? How it is related with machine efficiency?

When I am reading a journal about SRM (switched reluctance machines) it said that outer rotor design has better efficiency due to higher torque ampere ratio. How it is related with efficiency?
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0answers
81 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 ...
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1answer
50 views

power losses induction machine

I am totally lost in a question, how can be derived the friction losses of a induction machine based on this equation (It wasn’t given explication about these nor the bibliography/source of this ...
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4answers
4k views

Why is slip necessary in an Induction motor?

Why should the rotor of a 3-phase induction motor not rotate at synchronous speed?
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1answer
52 views

Where does come this power loss?

Regarding the next problem why is asumed that there was a power loss of 928 W>?