Central Tapped Transformer - wiring

Thread Starter

janger

Joined Nov 27, 2021
10
Today subject is Central Tapped Transformer 230V/110V CTE 3.3 KVA- site transformer
On the secondary site 110V CTE wiring diagram looks like that :

1.PNG261270147_1059577308138112_4975051133845576322_n.jpg






What would happen if I connect two outer terminals on the secondary side to the load like in the picture?
Would it be a short circuit and an appliance would burn? Or +55V and -55V would cancel each other and there would be a 0 V with no current flow?

I am a student and I am trying to find the answer.
 

Thread Starter

janger

Joined Nov 27, 2021
10
Based on images - If I connect one phase L1: + 55V and second phase L2 -55V together I would short the circuit and the current would be rushing up and I would burn a 110V appliance. The installed transformer circuit breaker would trip cutting off the power supply on the primary side. What do you think?
 

Thread Starter

janger

Joined Nov 27, 2021
10
I would wire this transformer to 240V socket protected by RCD 30mA and 110V - 55V 0V 55V center tapped earth like this. What do you think ?261318326_376612174214155_6034118283015376166_n.jpgr to
 

ericgibbs

Joined Jan 29, 2010
14,697
Hi j,
Is this Neutral to Earth because it's a House without PME.? Ref this link.

With regarding the centre tapped secondary they are not usually labelled +v and -v
Start and Finish of the winding/s is indicated in some way on the transformer or datasheet for the transformer and the Centre tap, CT.

Do you follow that, OK.?
E

https://www.emfs.info/sources/distribution/uk/
 

Thread Starter

janger

Joined Nov 27, 2021
10
The power supply is a 3 Phase consumer unit in an industrial environment - for the transformer was taken 1 Phase - I did a mistake in the drawing and Neutral isn't connected to the Earth at the board. Apart from the wrong Neutral and Ground Connection and wrong Voltage description is everything else ok? My homework is to do the correct wiring of this transformer and find out what would happen if I connect outer terminals on the secondary site together + do the wiring/circuit diagram.
 

Thread Starter

janger

Joined Nov 27, 2021
10
Summary then.

Question: What would happen if I link/connect two outer +55V and -55V terminals on the secondary side to the 110V load

Answer: If I connect one phase L1: + 55V and second phase L2 -55V together I would short the circuit and the current would be rushing up and I would burn a 110V appliance. The installed transformer circuit breaker would trip cutting off the power supply on the primary side.

Wiring diagram - I know what to do.

Thank you Ericgibss :)
 

MrChips

Joined Oct 2, 2009
25,036
You don’t connect neutral to earth.
Leave the centre tap not connected to anything.

At the secondary winding there is no +55V and -55V.
They are both 55VAC with respect to the centre tap.
 

Ian0

Joined Aug 7, 2020
4,119
Every day is a lesson - I did my best
View attachment 253684
This is a site-safety transformer. The load connects between the terminals you have labelled "Ve-" and "Ve+", and it gives you 110V AC. When the "Ve+" terminal is at +55V, the "Ve-" terminal is at -55V (and vice-versa 10ms later), so the voltage across them is 110V. (You do not connect the Ve+ and Ve- terminals together. The load does not connect to either neutral or earth)
Its purpose is to limit the voltage on a power tool to 55V AC, which is low enough to prevent a fatal shock in most circumstances.
 
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