Understanding three phase.

[Rampage]

I've heard many a time on here that people don't understand three phase enough to work on it.
Im just wondering what exactly people don't understand?

 

[Guest55]

why dont you explain the principles of it for everyone ?
seeing as you brought the issue up.
:-D

 

[mayfair]

Possibly they dont understand that if you mess with it the shock hurts a damm site more than single phase

 

[Rampage]

why dont you explain the principles of it for everyone ?
seeing as you brought the issue up.
:-D

lol
What do you want to know?

 

[Knobhead]

Possibly they dont understand that if you mess with it the shock hurts a damm site more than single phase

Phase to earth is just the same and you would have to be doing something very stupid to get the full 415V from two phases.

 

[Guest55]

Possibly they dont understand that if you mess with it the shock hurts √3 more than single phase

fixed that for ya.
;-)

 

[Rampage]

398v by current standards? (square root of 3 x the accepted 230v that Uo is)

 

[Guest55]

lol
What do you want to know?

everything you learnt in your 3 weeks of training.
;-)

 

[mayfair]

Tony your right but ! it does seem to hurt more from a one time only experience lol.

Phase to earth is just the same and you would have to be doing something very stupid to get the full 415V from two phases.

 

[dcelectrical]

reminds me of a memorable mistake i made in my youth was removing a drill bit from behind a 3 phase air handling unit motor and had to take off the perspex plate to get my hand down, i turned the breaker off and then went on a coffee break, while i was away the machine next to it tripped and a member of the team came in and isolated the unit that had tripped and put my unit back intthe breaker back onto my unit, i returned and poked my head into the board and then shoved my hand down to get the drill bit, i understand 3 phase

 

[Rampage]

lol

Three coils 120 degreesin a steam turbine or whatever is used. Neutral is taken from where the 3 coils are connected together. Line to neutral is 400vRMS (max. 565.6 volts) Line to earth is 230vRMS (max. 325 volts. A common misconception is that all lines supply power simultaneously but they don't this is why the neutral is the same size (cable) as a single phase.
Electrical items only using 400v don't need a neutral such as motors.
I don't know about 3rd harmonicas!
Star and delta are different ways of connecting to three phase but I don't know about star-delta switching on motors as it wasn't covered on my domestic installers course
you can creat a three phase supply by connecting (mechanically) a three phase motor to a three phase motor both at 3000rpm. This would give you three phase.

Think thats it. Pretty much everything on three phase that there is

 

[Guest55]

lol

Three coils 120 degreesin a steam turbine or whatever is used. Neutral is taken from where the 3 coils are connected together. Line to neutral is 400vRMS (max. 565.6 volts) Line to earth is 230vRMS (max. 325 volts. A common misconception is that all lines supply power simultaneously but they don't this is why the neutral is the same size (cable) as a single phase.
Electrical items only using 400v don't need a neutral such as motors.
I don't know about 3rd harmonicas!
Star and delta are different ways of connecting to three phase but I don't know about star-delta switching on motors as it wasn't covered on my domestic installers course
you can creat a three phase supply by connecting (mechanically) a three phase motor to a three phase motor both at 3000rpm. This would give you three phase. You could also do with with single three phase motor by supplying one coil with 230v, the other two coils would generate the other 2 phases, although admittitly this is a **** way of doing it.

Think thats it. Pretty much everything on three phase that there is

Thanks , i dont need to bother doing a HNC now you've explained all the theoretical science.
:-D

 

[Knobhead]

Don't give up the day job.

 

[Rampage]

Don't give up the day job.

Because your job would be in jepody?

 

[Paul.M]

You mentioned something about the neutral being the same size on a 3ph circuit? Someone may have something to say about that soonish lol.