Should I stick it out in EE with weak-ish math?

[sophiecentaur]

Power engineering and electronics can involve statistics, DSP, a knowledge of materials, feedback systems, noise theory, solid state Physics, EM theory - you name it. That's if you plan to be at the World-shattering end of things.
But don't let that put you off. There is always a niche for someone who is keen enough.

 

[psparky]

Hey Budda...here's an example of what I'm doing right now. I studied mainly electronics but now work mostly with power. V=IR either way.

Right now I'm doing the engineering for adding 2 - 350 HP motors to a factory. The motors are rated at 4,160 volts each. They are to be fed from 13,200 volt switchgear.

So I obviously need a transformer...more switchgear (large expensive breakers) after the transformer...and starters for each motor.

I have to size all the wires between each item I listed...use stress cones to connect them.

The transformer for this is huge. The Xformer is 8 feet wide...by 6 feet deep...by 7 feet tall! As you can see...we spend a lot of our time just seeing what will fit in a room not to mention the clearances you need between high voltage items.

For the switchgear after the xfmr...it will be three different cubes...400 amp main...followed by two 200 branch breakers...followed by starters. Those three cubes measure 9 feet wide by 7 feet deep!

Of course...the company hasn't decided whether they want a VFD or not...but in the meantime I'll put something together for the non VFD type.

This is real world engineering...and is happening right now! The toughest maths (haha!) I will use is either finding the overall KVA...or the current thru various parts. Pretty simple math! It's all preliminary what I'm doing...but this is how engineering works. You typically are missing a lot of information!

Incidentally...a starter is just a switch. Kinda like the light switch on the wall...but built massive to handle high voltage and high current. Almost all decent size motors need starters...unless they are VFD...then the VFD is the starter.

There is also a control wire that controls the starters. Whether it be a thermostat...pressure guage...or whatever. The signal excites the magnetic field in the starter relay and closes the contacts...therefore starting the motor and keeping it running until the "off" signal comes in.

 

[BuddhaBelly34]

While I don't know what all of it means the idea that your are creating something like that makes me extremely jealous! haha

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And as for the maths things, I think it has to do with:
Sciences - physics, chemistry, biology, etc
Maths - algebra, trigonometry, calculus, differential eqs, etc.

While math can be thought of as the entire field of mathematics, maths can be thought of as the individual components of the field.

JUST MY GUESS THOUGH, I'm definitely not a brit and I am about the furthest you can get from being an English major.

 

[psparky]

While I don't know what all of it means the idea that your are creating something like that makes me extremely jealous! haha

-------------------------------------------------------
And as for the maths things, I think it has to do with:
Sciences - physics, chemistry, biology, etc
Maths - algebra, trigonometry, calculus, differential eqs, etc.

While math can be thought of as the entire field of mathematics, maths can be thought of as the individual components of the field.

JUST MY GUESS THOUGH, I'm definitely not a brit and I am about the furthest you can get from being an English major.

Incidentally Budda...why do we need or use all these silly little breakers?

What's their use...think about it and reply.

 

[eemichael83]

As for the 'Maths', if you are just starting in learning Math subjects like Derivatives and Integrals, etc.. OR if you've been out of it for a bit and just want to brush up and review some things, I've found this guy to be very helpful and easy to learn (review) with: http://www.youtube.com/user/khanacademy?ob=0&feature=results_main

 

[BuddhaBelly34]

Thanks michael83 I subscribed to that guy.

As for why do we need all those things its essentially to scale down the power from the grid to be appropriate for the motors right? I didn't know off hand the function of any of those objects (except the transformer).

 

[psparky]

Thanks michael83 I subscribed to that guy.

As for why do we need all those things its essentially to scale down the power from the grid to be appropriate for the motors right? I didn't know off hand the function of any of those objects (except the transformer).

Good guess...transformers certainly change voltages...power in equals power out. So if you have 10,000 volts at 1000 amps...and you are dropping to voltage to 2400 volts...your amps will now climb to 4,160 amps...P=IV...remember...again, power in equals power out.

Now to breakers...these are the breakers that are in your electrical panel at home or in your apartment or whatever. Sometimes they "trip" and you need to reset them for whatever reason.

Why did they trip...well...take a typical 20 amp breaker in your house. Now let's say mom is busy and a 10 year old decides to play with two wires in a receptacle. He decides to touch them together. There is no resistance when they touch...so massive current goes thru the breaker and "trips" it. The outlet is no longer energized.

Now...let's say we don't have a breaker. Chilld touches two bare wires together...now there is a massive flow of current. The wires in your house start to melt and burn...everntually starting on fire...the transformer on your pole outside blows up...the wires running down the street turn bright red and you start the entire neighborhood on fire.

Ok...you can see breakers are to protect the wires! and the buildings the wires are in. Breakers are there to protect against short circuits...or overloads of amps.

And yes...the breakers in factories are gigantic compared to your house panel. A house 20 amp breaker can cost $5. A 13,200 volt 800 amp breaker in a factory could cost $100,000!
Big difference!

Contrary to poplular belief...breakers are not there to protect your human body. If you are getting shocked...not even 1 amp will be going thru your body. The breaker feels nothing and is perfectly happy...it will not trip! However...the GFCI receptacle in your bathroom or kitchen will trip in a shock situation!

 

[BuddhaBelly34]

Good guess...transformers certainly change voltages...power in equals power out. So if you have 10,000 volts at 1000 amps...and you are dropping to voltage to 2400 volts...your amps will now climb to 4,160 amps...P=IV...remember...again, power in equals power out.

Now to breakers...these are the breakers that are in your electrical panel at home or in your apartment or whatever. Sometimes they "trip" and you need to reset them for whatever reason.

Why did they trip...well...take a typical 20 amp breaker in your house. Now let's say mom is busy and a 10 year old decides to play with two wires in a receptacle. He decides to touch them together. There is no resistance when they touch...so massive current goes thru the breaker and "trips" it. The outlet is no longer energized.

Now...let's say we don't have a breaker. Chilld touches two bare wires together...now there is a massive flow of current. The wires in your house start to melt and burn...everntually starting on fire...the transformer on your pole outside blows up...the wires running down the street turn bright red and you start the entire neighborhood on fire.

Ok...you can see breakers are to protect the wires! and the buildings the wires are in. Breakers are there to protect against short circuits...or overloads of amps.

And yes...the breakers in factories are gigantic compared to your house panel. A house 20 amp breaker can cost $5. A 13,200 volt 800 amp breaker in a factory could cost $100,000!
Big difference!

Contrary to poplular belief...breakers are not there to protect your human body. If you are getting shocked...not even 1 amp will be going thru your body. The breaker feels nothing and is perfectly happy...it will not trip! However...the GFCI receptacle in your bathroom or kitchen will trip in a shock situation!

Considering we are way off topic now anyway this is a good time to ask:

I was skimming over the breaker article on Wikipedia and I saw that it said something about using oil/gas (not natural gas obv) to break the arc. Doesn't that seem a bit insane. Aren't all oils flammable?

 

[psparky]

Considering we are way off topic now anyway this is a good time to ask:

I was skimming over the breaker article on Wikipedia and I saw that it said something about using oil/gas (not natural gas obv) to break the arc. Doesn't that seem a bit insane. Aren't all oils flammable?

Not sure...but it would only make sense that the oil/gas activate the mechanical device that opens the switch. The oil/gas would be fully insulated from the "arc" part.

Otherwise...yes, it would explode or burn.

 

[sweetpotato]

Oil circuit breakers can be used for very high voltages. See this:

http://www.relectric.com/Circuit-Br...voltage-circuit-breakers-oil-circuit-breakers

There is definitely the issue of flammability.

FYI I've never used one myself.

 

[BuddhaBelly34]

Ah, that link helped quite a bit. I was trying to wrap my head around that.

Also, I can't believe I didn't think of oil being used to break the arc by activating a mechanical device. Obviously I was not reading or thinking very critically this morning.

But dang those breakers can get massive.

 

[psparky]

Ah, that link helped quite a bit. I was trying to wrap my head around that.

Also, I can't believe I didn't think of oil being used to break the arc by activating a mechanical device. Obviously I was not reading or thinking very critically this morning.

But dang those breakers can get massive.

I don't know much about the subject of oil breakers...but I will just throw out some random thoughts.

Perhaps the oil does surround the contactors. If so...when the contactors separated to be in the off position...there would be no air...therfore no arc!

Just a thought.

But then again...when the contactors went to close they would have oil on them possibly adding resistance...then again...maybe not. Perhaps the current would flow just lovely.

Again...just random...ramblings. I could google the subject...but that would just be no fun:)

 

[psparky]

I was thinking that oil may not work as an insulator because it is essentially "wet"...

But it turns out that oil does not conduct electricity because there are no charge carriers in it.