Understanding Engine Nameplate Voltage Ratings: 230/400V and 400/690V Delta/Star

Hello. Someone please enlighten me, because I`ve wondered about this several times, I`ve also tried to find the answer on the Internet, but I still don`t know.

The star-connected engine operates at 230V
The motor connected in a triangle operates at a voltage of 400V

So why on some engines the nameplate says, say, 230/400 delta/star and not star/delta. After all, a triangle is probably 400V. What this is about? Isn`t such an engine adapted to work in the Polish network?

Or an ordinary motor that I connect during practice with a time relay in the starting system has a triangle/star on the plate 400/690. Delta ok 400V but star 690V?

cxzcxz123 wrote:

The star-connected engine operates at 230V
The motor connected in a triangle operates at a voltage of 400V

Where did you read that?

The star voltage is always √3 greater than the delta voltage, so Δ230 Y400V, Δ400V Y690V

I`ve gone a bit crazy now. Well, star/delta switches rather than delta/star switches are used.
So if you wrote that the star voltage is higher, so the engine starts on the 400V star and then we give it 230V on the triangle?

No, the voltage is always 400V, 230/400V motors cannot operate in a 400V network on the Δ/Y switch.

That`s why the engine you have in practice is 400/690. At the start, you connect it in a star, so it gets a lower voltage than it should for a star, it consumes less current and has less power, because in a star it should operate at a voltage of 690V, to obtain nominal parameters, you switch it in a delta, so it works at the correct voltage of 400V, because this is the voltage for which built for delta connection.

cxzcxz123 wrote:

...The star-connected motor operates at 230V
The motor connected in a triangle operates at a voltage of 400V...

It`s exactly the opposite. The motor windings connected in a star operate on phase voltage (230V for a 400V network), and connected in a delta on the phase-to-phase voltage (400V for a 400V network).
In practice:
* the D/Y 230/400V motor can only operate in a 400V network when connected in a star manner. When connected in a triangle, it will burn.
* the D/Y 400/690V motor can operate in a 400V network connected in a star or delta manner. You will only achieve optimal working conditions with a delta connection. When connected in a star manner, the motor operates at a lower voltage, produces less power, but consumes less current.

aaa... .And finally someone explained it to me in two sentences, short and to the point. In fact, it always works at 400V, only 230V is the phase voltage for the star and for the triangle Uf = 400V

And how is it that, let`s say, we have on the board:
in one engine 230/400 delta/star
and in the second engine 400/690 delta/star

And in the first triangle it is 230V and in the second triangle it is 400V?

This means that the coils of the first motor have been adapted to a phase-to-phase voltage of 230V in a triangle and we will not connect it here, because our voltage is Umf = 400V. And such a motor can only operate in a star, because its coils when connected in a star are adapted to Umf = 400V.

Do I understand correctly?

EDIT:
User zetdeel wrote the answer to my next question faster than I wrote the question I was about to ask. Thanks for your replies.

cxzcxz123 wrote:

This means that the coils of the first motor have been adapted to a phase-to-phase voltage of 230V in a triangle and we will not connect it here, because our voltage is Umf = 400V. And such a motor can only operate in a star, because its coils when connected in a star are adapted to Umf = 400V.

You can use the Δ connection of such a motor to power it with a "single-phase" inverter if you do not have three-phase voltage, e.g. at home. The inverter generates three-phase 230V voltage at the output.

Added after 12 [minutes]:

cxzcxz123 wrote:

The star-connected engine operates at 230V
The motor connected in a triangle operates at a voltage of 400V

The statement "motor" is confusing, if it were "motor winding", the above statement is correct because in a 230/400V motor connected to a 400V network in Y, the winding of each phase is powered by 230V phase voltage, in a 400/690V motor connected to a 400V network in Δ, the winding of each phase is supplied with phase-to-phase voltage.

This drawing illustrates it best

Right, the phrase motor winding is more accurate. I saw this drawing while looking for an answer to my question.

And related to the topic, I now have a month`s internship and I make control cabinets for engines. Why do star/delta cam switches have two stars and two delta? (i.e. both left and right).

These are the so-called Δ/Y switches. "reversible", i.e. a left-right and Δ/Y switch in one.

Thanks a lot for your answers. Topic to be closed.