AC & DC Motor Theory

[Happy Jack]

Thought it was about time I started contributing. Thanks again to all involved for setting this area of the forum up.

Now, I'm acutely aware that this area of study represents something of a weak point for a lot of students. And a few practitioners, I'm certain. Like showing a dog a card trick, my vacant - yet curious - expression did little to inspire confidence in my tutor during lessons last week, so I'd like to better acquaint myself with the subject and return to class capable of some meaningful input.

While I don't have any specific questions relating to the particulars, and without much Google-fu, could anyone recommend any reading on this subject, online or otherwise? I'd also be curious to hear from those who work with motors and are happy to impart their knowledge on how best to navigate this subject, as there appears to be an awful lot to digest.

Thanks.

 

[Paul.M]

Hello Jack and welcome to this trainee section, nice to have you join in.

As for motor questions I'm not the best chap to ask. When I was doing my level 3 which a lot was on this subject, my best friend of 23 years passed away and then my dad died of cancer 4 weeks later. I missed a lot of college but the principle of the college refused my written resignation due to me helping out the students the year before on the level 2, all of them passed due to my and others helping them out in the classroom and the workshop. I took the exam and failed by 1 o 2 questions (doh). I re-sat the exam twice and passed on the second time. Although I passed the exam and the year I still looked in my Trevor Lynsley book and my college hand outs to understand the subject of motors. Motors is something that dos not come natural to me but I would recommend his book, get the advanced version and not the basic book. This will put you in the right direction mate. I'm sure that High Tower will be able too help you on this subject better than I.

 

[Marvo]

Can you give us an indication of what motor theory you've already been taught. It's such a wide field I wouldn't know where to start giving you info or at what level.

As with most things the world of motors has changed, especially over the last few years. When I was a learner girls were definitely girls and boys were boys, life was simple and there were no surprises. Same with motors, AC motors were AC motors and DC were......well DC.

Nowadays there's a lot more gray areas, girls and boys are no longer just girls or boys and AC motors operate with modulated DC carriers and DC motors are electronically commutated plus you get universal motors that like both AC and DC and then there's girls who prefer boys (who prefer boys that prefer girls). So basically nothing fits into the nice neat boxes and categories that it used to.

 

[Paul.M]

Reminds me of my young teenage life

https://www.youtube.com/watch?v=z1Ir489EpgI

 

[trev]

Didn't Tony do a pretty in depth thread on motors a few months back?

 

[Marvo]

Yeah he did but he dismantled it when he migrated to another forum. It was mainly large industrial motor arrangements though and I don't think a lot of it would have been relevant at basic theory level.

 

[Paul.M]

Didn't Tony do a pretty in depth thread on motors a few months back?

Is it still on this forum Trev???

I've got a few level 3 passed papers from this/last year, I'll post them up long as I dont get done for copyright.

 

[Marvo]

I don't think past papers would be a copyright issue, even if they are copyrighted there should be fair use applicable.

 

[trev]

Is it still on this forum Trev???

Yeah he still visits regularly

 

[Paul.M]

Marvo it has the name of the training company across them so I'm not too sure about posting them up.

 

[Marvo]

If they don't have any warning on them against distributing I would say you could attach them. You can also just make a thread out of each question at a time for trainees to make a stab and ask questions about anything that's not clear to them.

 

[Paul.M]

^^^ Thats what I was thinking Marvo. I'll type out each question in here in my own words and that way it does not infringe on copyright etc. Just takes me a bit longer to do lol. I'll post one question up per day if I can.

 

[Happy Jack]

A thank you for all the input, it is gratefully received. I shall respond in a little more depth tomorrow.

To paul.m, I'd really appreciate that. Past papers are always welcome.

And Marvo, while we've covered magnetism in some depth, last week was the first whole session dedicated to the different flavours of AC and DC motors, their basic construction and application.

As I say, I shall return tomorrow and respond in a little more depth. Thanks again.

 

[Happy Jack]

I still looked in my Trevor Lynsley book and my college hand outs to understand the subject of motors.

Would this be the title?

Advanced Electrical Installation Work: Level 3 City & Guilds 2330 Technical Certificate & 2356 NVQ: Level 3 City & Guilds 2330 Technical Certificate and 2356 NVQ: Amazon.co.uk: Trevor Linsley: Books

I've picked up 'Electric Motors and Drives' by Austin Hughes, from Newnes. The material appears to be well written and pitched appropriately, so I'll work through this one first.

Motors is something that dos not come natural to me.

No, without much background I feel the same. Right now the basic grounding in the subject just isn't there, and I'll really like to get a handle on it while the unit is fresh.

Can you give us an indication of what motor theory you've already been taught. It's such a wide field I wouldn't know where to start giving you info or at what level.

It is Unit 1 Outcome 6 of the 2330, so says the B&B literature. We've gone through the first two sessions, covered the magnetic principles that underpin operation, basic motor / generator construction and identification of parts, and the different types of motors, series, compound, cap start cap run, induction etc.

I suppose if I had a question, it would be to ask when and how the 'penny dropped' for those with a handle on the subject. Was there a particular moment you can look back on?

 

[Happy Jack]

Didn't Tony do a pretty in depth thread on motors a few months back?

Are you referring to this sticky thread?

http://www.electriciansforums.net/commercial-industrial-electrical/43777-motors.html

Some fantastic information there, but a shame most - if not all - of the attachments point to an invalid location.