Does it matter for the operation of the consumer from an isolation transformer or directly?

Question

Electronics

So I thought about how electronics or an electric stove or a computer will work, it doesn’t matter. If the connection is phase zero, and the second option is with an isolation transformer. When a distinct zero does not exist. What is the point here? On the nameplate of the device we read terminal 1 - phase, terminal 2 - zero 230-240 volts. But there is an isolating transformer. And now there is no pronounced zero on it, but there are two poles in the sum of which there are 220 volts. How does this affect the operation of the equipment? The fact that an isolation transformer serves to increase the electrical safety of electric shock is understandable. But there is no zero. That is, instead of zero, we supply a phase to the device, a total of 220 volts.

Answer 1

TL; DR - the use of an isolation transformer shifts safety priorities: -
without it - fire safety is a priority, insulation violation causes the automatic machine to work
- with it - protection against electrical shock is a priority, since the probability that a human body will be in this place after insulation failure is higher .
That is why an isolation transformer is used only where the device is in contact with metal parts with the human body - electric shavers and medical equipment.
Medical equipment is regularly checked by competent personnel against signature. Including insulation tests.
The end of the short version
About the power supply systems TN (neutral grounded) and TT (neutral isolated), I will not copy-paste here.
First you need to understand what a neutral is. In fact, the neutral is the middle point of the transformer winding. Actually, in the USA, for example, PE, N, L1, L2 comes into the house, and the
neutral is deafly grounded on the pole where the transformer hangs.
Between the neutral and any phase there is 110V, and between the phases (roughly) - 220V. Powerful consumers (boilers, stoves, chargers for Tesla) are hung between two phases, ordinary consumers - between zero and phase.
Moreover, in ancient times, a similar connection was also practiced in Russia - that is why there are two plugs on two wires in summer cottages - two phases came into the house.
Whether this affects the operation of appliances - and yes and no, depends on the specific design and the intervention of playful handles.
In most devices, there is an isolation transformer immediately at the input
(this list also includes a PC).
In other devices, made on the assumption that one of the conductors has a zero potential, the following will be observed - the circuit will be designed so that, for example, for capacitors (even non-polar ones), that lining, which is structurally external, will be connected according to the circuit closer to the point with zero potential (you yourself look for Mr. Carlson's video, where he explains this for an hour), so including such a device in a TT circuit or mixing up its phase and zero can increase the level of interference.
In addition, all switches and protection devices will be located on the wire that, according to the developers of the device, is a phase, because in this case the more "dangerous" conductor will break earlier and a smaller part of the switched off device will be at potential.
Conclusions: The
PC will be drummed, it has a symmetrical input circuit, and then comes its own isolation transformer.
Most electrical appliances are similar, they are not tied to phase-zero in any way.
The problem can come out of those devices where the circuitry is tied exactly to zero - but this still needs to be looked for such a miracle. For example, some kind of boiler that determines the presence of water in a conductive way - it has zero on the tank body, and the phase through the resistor is an electrode. If you turn the plug over to him, there will be a phase on the case. If you plug it into the TT circuit, the phase will be here and there, and most likely, through the capacitance of the Earth and the transformer, the device will be unpleasant to bite and pinch.
Actually, for these reasons, large loads are not connected through an isolating transformer with an isolated neutral:
- a violation of the insulation does not knock out the machine - this is the main reason, and it’s not far from a fire when the insulation is completely broken and an interphase occurs.
- even with good insulation, the capacitance of the transformer and installation remains, and the larger the transformer, the better this connection. This is more relevant for high voltages, over 1kV.