boriscerar

modified 4 years ago

Why is There voltage towards primary

177

02:08:22

I am wondering why is there voltage between primary and secondary; isn’t the secondary isolated from the primary and therefore floating? (I am aware I put the same ground, but it doesn’t work if I don’t put ground on the secondary) How so I fix this, please, so the secondary will be floating? I can replace the voltmeter with a load, and the current will still run…

published 4 years ago

Robert_Kidd

4 years ago

Why have you shorted out the secondary winding? As both windings are referenced to ground (as you realise they need to be to enable the simulation to function) then a voltmeter placed between the windings will display the potential difference (I.e. the voltage) between them.

Robert_Kidd

4 years ago

Remove the short from the secondary and connect the voltmeter across the secondary winding. Don’t worry about the apparent lack of isolation between the windings. In a real circuit you won’t ground both windings so you will have isolation.

boriscerar

4 years ago

Dear Robert, thank you for your reply. I didn’t place a resistor on the secondary, because it would pose no difference to my question. I am aware, in real case, secondary is isolated, but, if I am to demonstrate the isolating effect to a friend, or to explore stuff myself, there might be a way to do that in this wonderful software?

boriscerar

4 years ago

Removed short from secondary and added a resistor between primary and secondary to show the current flows between the two in the simulation.

Robert_Kidd

4 years ago

Obviously you can do what you wish but by putting a component between the windings you are demonstrating that there is no isolation. Surely better to not do this and explain to your friend that the ground point on the both windings is purely since the simulator needs a reference point? Up to you.

592azy2circuitdude

4 years ago

The isolation that comes from the transformer is due to the primary voltage and current being linked to the secondary by a magnetic field (NOT a direct wire connection). But by placing the primary and secondary on the same ground, it effectively connects them with a wire and the isolation is removed. However, as you and Robert pointed out this is required for the simulation to work and would not be necessary in practice.

592azy2circuitdude

4 years ago

I think you can simulate the isolation by placing a very large resistor between the primary and secondary coils. Please have a look at my circuit that I based off of yours. https://everycircuit.com/circuit/4973019682045952

592azy2circuitdude

4 years ago

The voltage between the primary and secondary coils is a puzzler for me. It appears to be due to the primary voltage and secondary voltage being slightly out of phase. This causes there to be a voltage difference between the two. This would cause a current to flow if a resistor connected between the two (as you pointed out). However Robert is right that if you do that then the isolation would be removed (not what you want!)

592azy2circuitdude

4 years ago

Hope this helps clears things up and doesn't make it more confusing 😄. Good luck.

boriscerar

4 years ago

592azycircuitdude, very nice of you to drop by again, thanks! Would sure be very nice if there would be an option to have the working isolation in this simulation.

badassfromaus

4 years ago

Is this what you are looking for? http://everycircuit.com/circuit/5041741184630784

faceblast

3 years ago

place a small capacitor between windings https://everycircuit.com/circuit/6400872982249472

boriscerar

3 years ago

Faceblast thanks, but we still have voltage if we do this.

boriscerar

3 years ago

Omg

boriscerar

3 years ago

badassfromaus: Thank you for your answer, but placing the capacitor does not solve the issue, since there still is voltage (and there shouldn't be any). I guess this is what we have to work with, since no other solutions have been proposed. Best regards and thank you for dropping by.

592azy2circuitdude

3 years ago

Please have a look at my circuit which I've updated and read the description. https://everycircuit.com/circuit/4973019682045952. Bottom line is EveryCircuit cannot do floating voltage calculations. Every component must have a reference to ground. If it doesn't, the circuit is greyed out. But by connecting a component between the coils, it allows the secondary to be referenced to ground, but keeps the coils isolated or separated.

592azy2circuitdude

3 years ago

I think that is the best you can do. Good luck!

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