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Join Date: Sep 2006
Posts: 31

AC Motor to Move a Train

11/06/2006 8:30 PM

I am a mechanical engineer. I am trying to use an electric motor to move a train in a factory, So I need a motor with a high stating torque but smooth in operation?

I will depend in my selection of the motor hosepower, that I will calculate the required torque and the required speed, This is right from mechanical point of view, but i dont know if it is right or wrong from electrical point of view, as there is something called rated power for the motor, and that the motor gives an output speed which is constant for a range of torques. So please can anybody clarify this point!

Thanks for you all

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Guru
Engineering Fields - Control Engineering - New Member China - Member - New Member

Join Date: Sep 2006
Location: CHINA
Posts: 2946
Good Answers: 14
#1

Re: AC Motor to Move a Train

11/07/2006 2:19 AM

Thats right, As you work out the power for the train moving you can select suitable tractive motor. power= torque x speed.

we can offer you that.

info@ndt.cn

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Guru
Engineering Fields - Control Engineering - New Member China - Member - New Member

Join Date: Sep 2006
Location: CHINA
Posts: 2946
Good Answers: 14
#2

Re: AC Motor to Move a Train

11/07/2006 7:08 PM

pls make sure here the term of speed is rotation speed not linear speed. because we use torque here not force.

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Anonymous Poster
#3

Re: AC Motor to Move a Train

11/08/2006 2:00 AM

Yes the rated power of motor is output power of the motor at a given speed.

for example for a 60 Cycle motor with a sync speed of 1800 RPM rated outut is typically measured at 1550 RPM about 87% of sync speed.

torque is the measured value at the rated RPM and from there onward you can get output power.

choice of motor should be on the basis of the what is the ratio of starting and running torque. if you need high ratio then you should go for DC motor. spacily series DC motor. AC induction motors are not going to give you high ratio.

further questions are welcome

King consultant

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Anonymous Poster
#4

Re: AC Motor to Move a Train

11/08/2006 4:04 AM

Traction motors are available driven by both AC and DC power supply but DC motor gives fine speed control and constant torque , where as AC motor output having narrow range of constant torque and speed at full speed .

acoording to load BHP can be calcualate and divide by motor efficieny to convert electrical energy to mechnical energy . final selection of motor can be taken next higher rating of motors.

please also look after the availability of type and rating of power supply in your factory before going to select AC/DC motor .

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Member

Join Date: Sep 2006
Posts: 5
#5

Re: AC Motor to Move a Train

11/08/2006 10:30 AM

Re: AC Motor to Move a Train

If your train does not require any speed control you can simply use an induction motor. It gives you high starting torque. Calculate your power requirement from load torque and speed add up 30 to 35% for adverse conditions and select a motor near to this power.

If you want a speed control you have to use a thyristor controlled panel. However you have add up power for less efficiency.

Amir Dutta

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Anonymous Poster
#6

Re: AC Motor to Move a Train

11/08/2006 1:50 PM

Try Dodge TXT motoreducers. 100% torque at zero speed,no matter the load. Try a power inverter to actuacte the reducer at will. We use it in aggregate bins.

Robb Garcia-Mexico

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Anonymous Poster
#7

Re: AC Motor to Move a Train

11/17/2006 6:41 AM

An inverter drive running an induction motor is the most common approach to your problem. Most motors have intermittent rating that allows higher kW output and starting torque but this must be verified with the motor being used. Intermittent ratings are limited by the heat sinking capacity of the motor, particularly that of the rotor and subsequent cooling. Therefore, if the application calls for less than rated speed with rated torque, you have to either cool the motor separately or use larger machine. This is heat-management problem to be integrated within the design parameter.

Controls may be force (torque), speed or position. If the application calls for reciprocating motion of a large mass without having inherent damping (friction, for example), it is beneficial to have regenerative braking. Depending on the energy recovered, re-gen back into grid or burn it out in the braking resistor.

External friction brake requires complex control system to provide smooth braking torque and transient, thus difficult for speed and position controls.

Excuse me, if all above was obvious to you.

pulto45

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