110V System?

[johnmccafferty60]

Hi. Wondering if someone would be able to explain how current flows in a 110V centre tapped transformer system. If both the live and neutral conductors are 55V to earth, how does current flow. It appears that there would be no potential difference between live and neutral if they are both 55V. Think I'm confusing myself but some clarification would be good, thanks!

 

[Lurch]

PD between live conductors is 110V. There isn't a neutral in a centre tapped 110V supply.

Get yourself a pen and paper and draw it out, or use Google as I'm sure there are already thousands of pictures and explanations.

 

[Essex1]

Welcome to the forum.

 

[johnmccafferty60]

Lurch
Thanks mate. I was just getting confused with the 55V aspect. Was looking online but thought it would be better to simply ask someone.

Essex1
Cheers.

 

[ProDave]

Remember it's ac, so alternating 50 times a second, so when one end is at +55V, the other end is at -55 (and for the purists I know that's not strictly correct)

 

[Lurch]

I was just getting confused with the 55V aspect. Was looking online but thought it would be better to simply ask someone.

In your drawing start with a straight 230-110 transformer. Add in the centre tapping.

The 110V never changes throughout. The centre tapping just gives you 55-0-55 as well.

(and for the purists I know that's not strictly correct)

Not in the slightest.

 

[johnmccafferty60]

Remember it's ac, so alternating 50 times a second, so when one end is at +55V, the other end is at -55 (and for the purists I know that's not strictly correct)

In your drawing start with a straight 230-110 transformer. Add in the centre tapping.

The 110V never changes throughout. The centre tapping just gives you 55-0-55 as well.

Not in the slightest.

So that 55-0-55 is simply for protection purposes?

 

[Lurch]

So that 55-0-55 is simply for protection purposes?

Pretty much.

 

[Andy™]

just to complicate this even more... if its a 3 ph transformer you have 63.5v to earth...

 

[johnmccafferty60]

just to complicate this even more... if its a 3 ph transformer you have 63.5v to earth...

Jesus...

 

[Nebakineza]

Hi john,

A centre tapped transformer works in pretty much the same way as normal, only difference being the separation of the secondary winding to allow two separate voltages across two lines. The current flows through a process of self-inductance between two magnetic fluxes, producing a back e.m.f which changes direction with each cycle of the current. The centre tap is another wire which is introduced to the middle of the secondary winding and is at zero volts, thus forming the neutral point between the two windings. That's what allows the two voltages, equal in magnitude but opposite in polarity. i.e +55V/-55V. There is 110V p.d across the two phases.

It's entire answer is more complex but that's more in relation to EE. Hope that helps though mate.