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http://i.imgur.com/VnJxMBK.png Just change generator phase angle - and voila - you've got DC-shifted sine wave.

This is not a bug.

It is a real effect.

You are seeing the effect a large L/R time constant with the transformer primary inductance and small primary series resistance in series with a zero resiatnce voltage source.

Run the sim for hundreds of cycles and increase the transformer primary resistance to see the secondary voltage decay to a swing that is symmetrical about zero after a while.

:)

BTW: please post sims and not pictures of sims. It's a pita to have to recreate someone else's sim just to help them out.

Fixed by "Skip Initial" option. Thank you for your help!

Be careful with the "Skip Initial" option.

Unless you are sure of what the steady state response or solution looks like you can be fooled by the "Skip Initial" option giving you a misleading answer.

You are much better to use the option of running a long sim (Stop Time) but only showing the results for just before the end (Start Time) so you get the (hopefully) steady state end of the sim after all the transient bagaviour has settled down.

For example, if the circuit has an oscillatory response then the Strart Time - Stop Time option is a safer choice because it will show you what the circuit is actually doing. The Skip Initial option may pick the wrong starting point for the sim and you could end up looking at a screen ful of feasible looking nonsense.

I am using 10 seconds start time and Skip Initial simultaneously. Does it make sense?

Can't tell.

You've not posted the circuit so you've not given details of the transformer inductances and resistances. Hence there's no way to estimate the L/R time constants that you have in your sim.

You say you are using a Start Time of 10s but you have given no information about the Time Step or the Stop Time that you are using.

Therefore it's not possible to make any firm predictions of what the response should look like during the time that your sim would be showing if you had not ticked "Skip Initial".

Yes, it was my fault to ask the question that way. In fact I see that all transients process are "settled down" enough after 8 sec for the specific circuit. The question is actually "are there any reason for using Skip Initial feature" at all in this case? Are there any profits or penalties?

It's worth trying because it can reduce the simulation time but always sanity check against a full sim (maybe with a delayed Start Time so you only look at the end of the sim).