How transformer is responsible to isolate the power supply

[shaswat]

I want to know that in most of the circuit for the purpose of isolation,transformers are used.These transformer acts as a isolation between the secondary and primary part of the circuit so that in case of ripple or any unwanted spikes doesn't affect the output/input circuit.My question is that how a transformer isolate the two circuit?(Is it all about the isolation or is it something like providing two ground).
I know that using primary & secondary winding can isolate the supply but how is it possible?Why any changes in the input or output section doesn't affect the other one?How a tranformer tackle a leakage current in case any in the circuit
Is this is the only reason of using transformer in the circuit or there is something I missing. If I don't want to use the transformer is there any method to isolate the circuit.
Any comments and ideas would be appreciated..

 

[ku637]

wikipedia says

Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow; no metallic conduction path is permitted.
Energy or information can still be exchanged between the sections by other means, such as capacitance, induction or electromagnetic waves, or by optical, acoustic or mechanical means



Transformers couple by magnetic flux. The primary and secondary windings of two transformers are not connected to each other
The voltage difference that may safely be applied between windings without risk of breakdown (the isolation voltage) is specified in kilovolts by an industry standard
If two electronic systems have a common ground, they are not galvanically isolated.

Optocouplers transmit information by light waves.
Capacitors allow alternating current (ac) to flow, but block direct current; they couple ac signals between circuits at different direct voltages

Hope that helps ..

hese transformer acts as a isolation between the secondary and primary part of the circuit so that in case of ripple or any unwanted spikes doesn't affect the output/input circuit

i seriously doubt it , a normal transformer in my opinion shall pass AC so it won't block ripple or spikes..Correct me if I'm wrong here..

 

[shaswat]

Wikipedia also says Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials.(Why its used "may").I am also doubtful on this comment.I found a question on some other site
https://electronics.stackexchange.com/questions/70237/effect-of-an-isolation-transformer-on-leakage-current
This question confuse me alot.

 

[tpetar]

Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow, no metallic conduction path is permitted. Energy or information can still be exchanged between the sections by other means, such as capacitance, induction or electromagnetic waves, or by optical, acoustic or mechanical means.

Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental current from reaching ground through a person's body.


Galvanic isolation
https://en.wikipedia.org/wiki/Galvanic_isolation


Best regards,
Peter

 

[shaswat]

Somebody already post that answer and unable to elaborate it.So if possible then could you please elaborate this one as I already checked the wikipedia link before posting this question

 

[tpetar]

Somebody already post that answer and unable to elaborate it.So if possible then could you please elaborate this one as I already checked the wikipedia link before posting this question

You didnt understand how galvanic isolation works or purpose of galvanic isolation ?


Best regards,
Peter

 

[Venkadesh_M]

I want to know that in most of the circuit for the purpose of isolation,transformers are used.These transformer acts as a isolation between the secondary and primary part of the circuit so that in case of ripple or any unwanted spikes doesn't affect the output/input circuit.My question is that how a transformer isolate the two circuit?(Is it all about the isolation or is it something like providing two ground).
I know that using primary & secondary winding can isolate the supply but how is it possible?Why any changes in the input or output section doesn't affect the other one?How a tranformer tackle a leakage current in case any in the circuit
Is this is the only reason of using transformer in the circuit or there is something I missing. If I don't want to use the transformer is there any method to isolate the circuit.
Any comments and ideas would be appreciated..

Transformers produces isolation between two devices you want to know how..

By means of different (grounds)..
By varying DC offset (like in amplifiers)
By giving safety to small circuits(in SCR triggering)...

Here comes your question "How a pulse transformer products a triggering circuit from Power thyrister circuit?"..
the power never going to come through pulse transformer and affect the triggering circuit, But what will happen if you directly connect them and That is isolation (optocoupler also can do this control applications but they wont help us in power applications)

 

[Borber]

Answer may sound too philosofic but. Only existing connection between primary and secondary windings is magnetic field and magnetic field does not conduct electric current. So current from primary supply source can not flow to secondary side. That's isolation.