i need to learn motor control

[capybara]

can anyone pls recommend to me a website or book to learn motor control
for 120v or 277/480 3 phase motors? it should be simple enuf that an
electrician (me) can understand it, not theoretical but practical
i need to learn this for work

 

[CycloWizard]

Not sure if this is quite what you're looking for, probably too basic if you need enough detail to actually work on them, but this site is great for general information about anything.

http://science.howstuffworks.com/motor.htm

Other links that looks like it might be useful:
A little theory (very basic)
Homemade 3 phase motor

If you let me know more what type of information you need I might be able to provide a better link. Hope this helps.

 

[Geniere]

http://www.epanorama.net/links/motorcontrol.html#ac

 

[harrkev]

If all you need is forward/reverse/off, you can use a couple of high-amperage contactors.
Wire up a 3-pole contactor to turn the thing on/off.
Wire up a 2-pole contactor to swap any two phases for forward/reverse.
That's it! Since you seem to have some electrical knowledge, obviously you know to make the contactor large enough to handle the voltages and currents involved. Keep in mind that motors are almost a purely inductive load, so you will get arcing on the contacts upon break, unless you take measures to prevent this. You can find large contactors at any air conditioning parts supply store (especially ones that have parts for commercial A/C systems).

On the other hand, if you need speed control, then you are getting into the realm of generating the phases yourself, which is NOT a beginner's topic. You are much better off buying a motor control box.

 

[capybara]

harrkev, ur the greatest, thx.
thats what i <3 about ATHT i always get the one paragraph solution im looking for

 

[KMurphy]

Here is a forum that can answer any question you may have about motor control.

http://www.eng-tips.com/threadminder.cfm?pid=237

Also, check out the NEC 2002 code book for requirments on circuit ampacity, overload requirements, etc.

Generally, you need to think about how to start and stop the motor, overload protection, fault current protection, ground fault protection and interlocking start/run permissives.

For variable speed AC, there is one (possibly more) manfucturers of single phase input/output variable speed drives. Variable speed DC is easier, but DC motors are more expensive. VFD's have come way down.

There are three main topologies to motor control; 2 wire, 3 wire or 4 wire start/stop.

2 wire uses the same contact to both start and stop (energize and deenergize) the main contactor.

3 wire has individual run and stop contacts, but they share a common leg because the motor control circuit consists of one voltage.

4 wire again has individual run and stop contacts, but two control voltages are used in the motor control circuit. This is usually where power circuit breakers are used for larger medium voltage motors (2300V, 4000V and 13.2kV greater than 1500HP).

Each has advantages over the other, but 3 wire control is the most widely used for normal applications. If a PLC or other control has complete control of the motor, then 2 wire is usually used.

Let me know if you would like a specific quesion answered. I troubleshoot and design quite a few of these a month.

 

[capybara]

Kmurphy - thx for the good link

 

[stnicralisk]

Originally posted by: capybara
can anyone pls recommend to me a website or book to learn motor control
for 120v or 277/480 3 phase motors? it should be simple enuf that an
electrician (me) can understand it, not theoretical but practical
i need to learn this for work

First I recommend spelling "enough" properly.