Is 4x2.5 mm Cable Sufficient for an 11 kW Motor?

Hello
What will be the appropriate cable for an 11 kW motor, or will 4x2.5 mm be enough?

A 4x2.5 cable should be enough for this engine.

Hello
Well, I would disagree with the previous statement
First of all, the cable should have five wires
Secondly, what about the starting current!
Personally, I would use at least 5 x 6 mm2
Regards

I`m not really an expert in this topic :/ that`s why my question: what is the 5th wire for and what is the starting current?

Specific and to the point answer:

I assume that the motor works in a star, we do not use N, we connect PE, i.e.:

4x4mm2 for electrical installation pipe, maximum cable length is about 90 meters.
For cables laid directly on the wall or on the floor, 4x2.5mm2 is enough, but the maximum length is about 50 meters.

If the motor has a delta-star start, unfortunately it will have more veins. If you want to keep the engine, you have to give it a larger cross-section...

There should be a 6mm2 cable in the switchboard.

The cross-section and length of the cables will guarantee (if the protection devices are selected correctly) the correct operation of the engine and protection devices.

Quote:

I assume that the motor works in a star, we do not use N, we connect PE,

Hmmm This is probably a new theory
I always thought that the N cable was not needed for the triangle

Quote:

so my question: what is the 5th wire for and what is the starting current?

The fifth wire I wrote about is protection, or grounding
The starting current occurs when the engine starts. Its value may reach several amperes. The operating time of the starting current depends on the time when the engine accelerates to the nominal speed.
Correct me if I`m wrong
Regards

Quote:

Hmmm This is probably a new theory
I always thought that the N cable was not needed for the triangle

And did I write differently? I pointed out that we do not use N, so I don`t know why you need five veins - you suggested marking the matter this way, because I understood this:

U, V, W, N, PE, so there are your five wires and I indicated that N is redundant... so there are four wires left...

Apart from that... finally a three or a star, because you write about a triangle, I write about a star...

Kobra wrote:

First of all, the cable should have five wires

There is no need for this, the motor itself only needs three phase wires to work, the fourth is PE.

Quote:

And did I write differently?

Yes, yes

I think you`ve mixed up some concepts
The star (you wrote about) requires a five-wire power supply
A triangle of just four
Either way, protection is required and unfortunately people forget about it

kiecio wrote:

Hello
What will be the appropriate cable for an 11 kW motor, or will 4x2.5 mm be enough?

The fairies went on vacation. Maybe some data from the tablet? E.g. In? Un?
The starting current may be as high as 10xIn (often it is several hundred amperes, not a dozen or so). In case of heavy (long boot) this is a serious load on the network.
I wouldn`t recommend less than 4mm2. I once saw an 11kW motor connected to the test with 1.5mm2 wires, which boiled the insulation after two minutes.

Kobra wrote:

The star (you wrote about) requires a five-wire power supply

It requires three phases and PE (or PEN), just like a triangle.

if it is 11 kW, it has a rated current of approximately 23 amperes, on average it is assumed to be 5-6 amps per mm2, so 4 mm2 may get warm when the engine is fully loaded
I recommend 6mm2
the motor should probably be connected in a delta via a star-delta switch, so there is no contactor for control and the 5th wire of the cable (blue) is not needed
a 6mm2 cable will easily withstand the starting current on the star (but after acceleration, you need to switch to the triangle because on the star it has 1/3 of the power)
but three phases and grounding yes

Hello
A little bit of data (what boot and connection).
It`s best to check it using a slider like:
http://www.moeller.pl/Programs/suwak_pkz.exe
Regards

SZYMKA10 wrote:

the motor should probably be connected in delta via a star-delta switch

so I can connect it to T/G even if I have the markings 290/500v?

As above

Madrik wrote:

The fairies went on vacation. Maybe some data from the tablet? ...

The engine does not always require G/T switching, what is it for, is it hard to start, what is the power supply.
When determining the cross-section, it is also important how the cable is routed and how the motor is protected... (in most cases, a 4x4 is enough for an 11kW motor).

I have several 11kW units with direct start and it is not a problem at all.
Moreover, I have the impression that some people treat this forum as for clairvoyants and unnecessary discussions begin.
You just need to ask the question well. I have an engine of ... power ... etc., located at a distance ... from the switchboard, starting ... (e.g. light), the cables will be laid ... (e.g. in a gutter), etc.
To answer the question - when it comes to current carrying capacity - a 4x2.5 cable is insufficient in some cases, it is better to use a 4x4 cable.

Gentlemen, please note that this is a 500 V motor, so the rated current is approximately 17 A.
A cable with three loaded conductors, laid in air at a design temperature of 30°C, with a cross-section of 2.5 mm^2 conductors, has a long-term load capacity of 25 A and a permissible short-circuit density of 1 second is 143A/mm^2. (PN EN 60364-5-523:2001 and Telefonica catalogue)
Regards.

JK60 -

Quote:

I have several 11kW units with direct start and it is not a problem at all.

At "home" - I guess it means in the company where you work... / your own transformer station / and not connected to the public network. As for the cable for this 11KW, definitely 4x4, even if it is 500V. The norm is the norm, and life and common sense have their own... By the way... recently I saw an engine /11KW, 400V/ drawing almost 40A from the network during operation... of course, the "expert" had previously set the thermal limiter to max-42A. The light was dimming... but he kept walking... until, of course, he burned out...

Akrzy74 wrote:

JK60 -

Quote:

I have several 11kW units with direct start and it is not a problem.

At "home" - I guess it means in the company where you work... / your own transformer station / and not connected to the public network. As for the cable for this 11KW, definitely 4x4, even if it is 500V. The norm is the norm, and life and common sense have their own... By the way... recently I saw an engine /11KW, 400V/ drawing almost 40A from the network during operation... of course, the "expert" had previously set the thermal limiter to max-42A. The light was dimming... but he kept walking... until, of course, he burned out...

My posts are about electricians, not idiots who set thermal protection "so that it doesn`t go off".

But how can you tell a patsy/gardener apart? /, from a veteran electrician - such a new profession: electrical gardener... .Such reasoning "so as not to knock out" can often be found in mines... - someone else will come, diagnose and repair...

How long should this cable be? 4x2.5mm² may not be too much, but I recommend 4x4mm², it will have a slight margin.

Akrzy74 wrote:

At "home" - I guess it means in the company where you work... / your own transformer station / and not connected to the public network.

Of course it is, and this 11kW engine is supposed to work in the kitchen of a residential building as a fan. I wrote earlier, there was little data (if I were a clairvoyant, I would receive about 37 bubbles today), and the answer to this question has already been given many times.

Since the engine is quite old, it is difficult to read anything from the nameplate, but it provides some detailed data:
TYPE S1-160-L-3
IP-44
290/500V 50 ?
0.80 ? 311/18.1 ?
960 rpm B-3
I couldn`t read where there was a question mark :/
The engine will drive 2 circular saws with a diameter of 630 cm
I don`t know what type of current, I can only say that it will work in a private household on a cable about 50-60 m long.
Currently, half of the section has a cable of probably 4x1.5mm (aluminium) and the other half has a cable of 4x2.5mm (copper) (the 5.5kW motor runs without any problems), now it is being replaced with an 11kW one and hence these questions:
-what cable
-what security
- how many amperes of the switch and whether the connection is G or T or G/T
Well, I guess now this data is enough and I also have fuses... I have B25 in front of the meter and C25 behind it
And now they`re asking for some feedback

You won`t be able to fight much with these safeguards.
500V motor in a 400V network, for now try it without major investments and see how it will work. Maybe someone has already tried it and will comment.

From what I found out, it won`t work without rewinding, a new 11kW with these speeds costs about PLN 2,000

[I am adding for clarity] With a new or rebuilt engine:

First, replace the protection in front of the counter with C25. In the long run, you need to increase the power allocation because you will not be able to use other devices during startup.
G/T switch, 4x2.5 Cu cable but from the contactors to the motor 7x (for peace of mind I would use 4x4)

How many amperes is the switch and is it really G/T?

So this will be the data from the table
TYPE S1-160-L-3
IP-44
290/500V 50Hz
cos φ 0.80 31.1/18.1 A
960 rpm B-3

it looks like a mine engine, I haven`t dealt with anything like that before, but from what I remember from school, this engine will spin when powered from the 230/400V network, but it will be weaker, i.e. it will have less than 11kW

I don`t agree with the suggestion JK60 replacing the fuse behind the meter with a slow-blowing C25 fuse because there is such a thing as gradation of protections and why do you need two C25s one after the other and you never know which one will work first.

As for rewinding, the cost with shipping and replacement of bearings would be around PLN 1,500 or less

So a 25A switch will be enough for this engine, because the seller in the electrical store offered me a 63A for this engine for PLN 160 and the 25A one costs PLN 80, so I`d be pretty pumped :/
The engine is quite old and from what I can see, it is star-bridged and apparently it used to work that way, so according to @Daj`s opinion, can I use the Star/Triangle switch without any worries?
As for the B25 protection that I have in front of the meter, when I turn on the 5.5 kW engine, something sizzles in it :/

To calculate protection and cable cross-section, I recommend the Suwak3 program. From 0.06 to 355 kW.

Sorry, I was a bit hasty, the plate states that the motor operates at a voltage of 290/500V, i.e. the phase band has a calculated rated voltage of 290 V, and when using the Y/Δ switch and powered from the 3x400 V network, each phase of the motor will receive a voltage of 400 when connected in Δ. So V probably won`t stand it and will burn

This means that the Y/Δ switch cannot be used in this engine