Mains Electricity (and a thanks)

[carlosthejackle2001]

Hi there,

I've just completed my HND in electronics (a thanks to the people that put me in the right direction with my project - worked on bread board but unfortunately didn't work on pcb) and am moving on to further education.

The picture shows my project in it's working state - the idea was a code entry system combined with a infra red link - i.e. type in the right code and the system will grant access...... wrong code too many times and you'll be locked out......


Does anyone know of good material on the net about mains electricity?? All I really know about it, is that it comes into the homes and powers your equipment - I'd like to know how.

 

[TillEulenspiegel]

I'm not familiar with the terminology , if I'm correct what you mean is the main feed to the house. The way to control that would require a contactor of high A (100+ A)
If You mean a single circuit the best way to interface your circuit with a single circuit the solution is an SSR -solid state relay- most have a 3-40v input and a 110-220V output with variable amperage.

The question of so many tries then Your lock is disabled, requires an incremental loop in one of the registers and a RTC to disable the numeric pad input for x time. Don't know what controller your using but if it it's a pic Nigel Goodwin ( a board contributer ) has a link to his site w/ tutorials for the pic series.

 

[Nigel Goodwin]

That's vastly over complicated! - if you check my PIC tutorials I give details of a combination lock, which (because it's just software) you could easily modify to lock out after a number of failed attempts (or any other facilities you wanted). It uses just one 18 pin PIC, and even has an LCD display so you can see what you're entering!

 

[carlosthejackle2001]

Yeah thanks for pointing out it's over complicated! I knew it could be done with 2 programmable (pics) chips (well thought that - think i did have a look at your site nigel in the early stages of my project when hunting down possible solutions) It was a learning experiance to use technology that I had learnt putting theory to the test, like the 555 etc... and perhaps my presentation was a little more interesting than explaining code perhaps.

Also I had no experiance with pics programming langauge so didn't feel I had enough time to learn the basics although it's something I'd like to look into. We learnt a simulated version of ASM and the building blocks to C++.


I'm just interested in knowing more about 'Mains' electricity, I don't want to be messing with it!

 

[Nigel Goodwin]

I'm just interested in knowing more about 'Mains' electricity, I don't want to be messing with it!

What do you want to know about it?, basically it's a fairly high current 230V 50Hz single phase supply, with the neutral connected to ground at the substation. The substation itself is three phase, with alternate houses connected to alternate phases, this is to balance out the load across the three phases, and allow a thinner neutral wire - thus saving money.

 

[carlosthejackle2001]

I don't know, I'd just like to know a bit more than it's a power source for plugging your tv into n stuff.

 

[Optikon]

I don't know, I'd just like to know a bit more than it's a power source for plugging your tv into n stuff.

The power companies generate via large generators that are powered by usually steam from coal burning, or nuclear or via turbine from wind or water.

The voltages are stepped up to many Mega Volts for long distance travel, when they get to supstations, they are stepped back down for distribution.
They are transmitted as 3-phase.

You can have 110-120, 220-240, even 480 delivered. If you are a factory, you might want 3-phase 480V for running large motors etc... If you are a household, maybe you just need single phase 120V and 220 for stoves, washer/dryer etc... The consumer markets in US have developed around 110-120V and 220/240V for larger items. Other voltages are available.

Depending on what civilized country you live in, the frequency is regulated to 50 or 60 Hz. and it is good to something like +/- .001 Hz. So, it is regulated and you can use it for CRUDE clocks if you need it.

Due to all the horribly non-linear loads on power lines and effects like lightning, there are very nasty transient events that occur to look out for.
When designing, one must take into account low-line and high-line conditions and transient protection. Nearby lightning strikes can cause thousands of volts to appear briefly on the line.

Complete industries exist for the sake of circuit protection and overload protection from events on the mains power.

 

[captainkirksdog]

If you REALLY want to know about AC-mains power generation, then I would suggest a field trip and tour of your local power-generation company. Most of them are delighted to show off their stuff and it can be a very cool experience. I have visited nuclear plants (these might not be possible to tour since 9/11), several different coal-fired types, and even been to the BOTTOM of a hydro-electric dam! Man, was that place COLD! The loudest noise I have ever heard was from a coal-dust fired jet engine powerplant about four stories tall!
You can walk away from an experience like this with a head full of knowledge and a heart full of memories. Good luck!