Why industrial motors etc need 3 phase power?

AI Thread Summary
Industrial motors require three-phase power for efficient operation, providing a constant rotating magnetic field essential for their function. In contrast, high-speed trains like the TGV utilize single-phase power (25 kV AC) but rely on advanced electronics, such as variable frequency drives, to manage traction motor speed and performance. Industrial motors are designed for specific tasks, often starting with limited current to manage hard starts, while trains need to vary speeds for optimal performance. The three-phase configuration allows industrial motors to achieve consistent RPMs based on line frequency. Overall, the differences in power requirements reflect the distinct operational needs of industrial motors versus traction motors in high-speed trains.
Charles123
Messages
131
Reaction score
0
Why industrial motors etc need 3 phase power and something like a TGV (high-speed train) only needs 1 phase (25 kV AC railway electrification), and yet its capable of such performance?
 
Engineering news on Phys.org
I don't know much about the train, but I suspect it has a bucket-load of expensive electronics supporting it's motors. Industrial motors that hard start and go one speed are serving a different function than traction motors, which must vary their speed. In all likelihood, your train has a three phase, variable frequency drive on the traction motors.

Typical industrial motors are minimalistic. The three phases are oreiented such that a constant rotating magnetic vector spins around at some ratio of the line frequency (i.e 1:1 - 3600RPM, 1:2 - 1800 RPM, 1:4 - 900 RPM).
Typically, they'll start with some means of limiting the current demand (i.e operating in a Y configuration), and then as they speed up, they switch to a full power configuration (Delta).
 

Thread '3-terminal device external modeling'

Very basic question. Consider a 3-terminal device with terminals say A,B,C. Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL) establish two relationships between the 3 currents entering the terminals and the 3 terminal's voltage pairs respectively. So we have 2 equations in 6 unknowns. To proceed further we need two more (independent) equations in order to solve the circuit the 3-terminal device is connected to (basically one treats such a device as an unbalanced two-port...
View full post »

Thread 'Question about the voltage between two charged capacitors'

suppose you have two capacitors with a 0.1 Farad value and 12 VDC rating. label these as A and B. label the terminals of each as 1 and 2. you also have a voltmeter with a 40 volt linear range for DC. you also have a 9 volt DC power supply fed by mains. you charge each capacitor to 9 volts with terminal 1 being - (negative) and terminal 2 being + (positive). you connect the voltmeter to terminal A2 and to terminal B1. does it read any voltage? can - of one capacitor discharge + of the...
View full post »
Thread 'Weird near-field phenomenon I get in my EM simulation'

Thread 'Weird near-field phenomenon I get in my EM simulation'

I recently made a basic simulation of wire antennas and I am not sure if the near field in my simulation is modeled correctly. One of the things that worry me is the fact that sometimes I see in my simulation "movements" in the near field that seems to be faster than the speed of wave propagation I defined (the speed of light in the simulation). Specifically I see "nodes" of low amplitude in the E field that are quickly "emitted" from the antenna and then slow down as they approach the far...
View full post »

Similar threads

Asymmetrical grounding of a 3 phase motor being run on a 1 phase supply
Replies
7
Views
3K
Understanding AC Motor Basics: Why a 120V Motor Can't be 3-Phase
Replies
4
Views
3K
Convert 1 phase to 3 phase by using an old washing machine
Replies
19
Views
3K
Self excited induction generators and grid connected solar inverters?
Replies
9
Views
2K
What Could Be Causing My 3 Phase Motor to Lack Power and Torque?
Replies
23
Views
6K
A little help understanding 3 phase waveforms and summation
Replies
5
Views
2K
Determining motor/control options to act on a spring
Replies
1
Views
1K
Battery Powered Electric Motor and Charging Requirements
Replies
5
Views
3K
Antique electric railway maintenance equipment
Replies
1
Views
325
Finding the Torque vs RPM curve for a 3-phase AC induction motor
Replies
4
Views
3K

Hot Threads

Recent Insights

Back
Top