VSD power point presentation? 1

[sparkyMV]

Hi there,
I am in Africa and I need to put on a very basic course on the theory, operation of voltage source VSD's for the local electricians. Do anyone have a link or a doc that I could use on a overhead for this training?
thanks in advance.

 

[ozmosis]

sparkyMV
This may be of assistance:

http://automation.usa.siemens.com/step/default.html

it is a combination of an online learning program as well as booklets you can download too. It has been developed for the USA market but is fairly understandable for markets in the ROW.

 

[sparkyMV]

thanks sed2developer, there is a lot of good stuff there.

 

[Skogsgurra]

Nice work.

But there are a few things that doesn't make it ideal as an introduction in electricity.

First (in the very very basic introduction to electricity), the author has chosen to define current as electron flow. But keeps conventional polarity definitions. That makes a resistor having a negative value, a generator generating negative power et cetera.
This will cause a lot of confusion and even if it is correct that electrons do the real job, I think that the confusion it brings when you are "correct" at this stage is very unfortunate and should be avoided.

Also, the 5.6 kohm resistor shown has a green, a blue and a brown ring. That is a 560 ohm resistor. Not good.

I haven't checked further.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

I am not sure I agree about that resistor Gunnar - the body of the resistor is brown, and the band is a murky ochre colour. It could be orange or brown. A better example could have been chosen where the colours are more distinct though.

The current flow is the main reason why I have not pushed harder for this to be incorporated into our operator training. It is a shame that when the convention for current flow was established many years ago it was based on fictitious positive charge carriers!


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I don't have an attitude problem. You have a perception problem...

 

[Skogsgurra]

Orange or brown - both are wrong for a 5.6 k resistor. It should be red. There may be shades of red, though. The red shown in the previous picture (battery) is red enough for me.

I did some further reading. It is comforting to see that the electron flow convention doesn't stay very long. The part about AC has conventional current flow so that a sine voltage in an inductor produces a current following the voltage with the usual 90 degree lag.

But, why then create the confusion in the first place? If it is for sparkys and not a physics class, I think that the electron flow concept is just plain unnecessary.

There are also sections about a relay (or is it a contactor?) where the artist hasn't quite got it. And there is a complete misconception about permanent magnets. They are shown to have a magnet field similar to that of a current carrying coil. They have not, they are dipoles and the field has two very distinct poles whereas the field of a coil consists of closed circular/elliptic paths.

I do not like that a big company like Siemens does a lot of mistakes like this. Especially since most people tend to think that facts from Siemens has been checked thoroughly and thus cannot be questioned. It can, and it should be. Patrick (or Jeff); I think that you should bring it up with the PR department. You do not like that your customers think you don't know about electricity and magnetism, do you?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScottyUK]

Hi Gunnar,

Looks like I should find that thread on resistor colour codes and read it again. I can't believe I made that mistake AND committed it to print!

Maybe (one of) Siemens' customers really doesn't know that much about electricty...


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I don't have an attitude problem. You have a perception problem...

 

[Skogsgurra]

Why so humble, Scotty? You, if any, know about these things. That you have proven over and over again!

Is it part of the attitude problem you mention?

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...