Tek hat şeması kaçak akım rölesini de içeriyor.

It means single-line diagram or one-line diagram.

• tek = single, one
• hat = line
• şema = diagram, schematic
• şeması = its diagram / diagram of ... in a compound structure

As a whole, tek hat şeması is a standard technical expression for an electrical single-line schematic.

This is a technical term meaning residual current relay, earth-leakage relay, or sometimes more generally RCD/RCCB, depending on context.

Breaking it down:

• kaçak = leaking, leakage
• akım = current
• röle = relay
• rölesi = relay of ...

So kaçak akım rölesi is literally something like leakage current relay.

Because it is the direct object of the verb içeriyor (includes/contains), and in Turkish a definite direct object usually takes the accusative ending.

Here is the structure:

• kaçak akım rölesi = the residual current relay
• kaçak akım rölesini = the residual current relay as the object

So in this sentence, the diagram is including that item, so the object appears as rölesini.

Because kaçak akım rölesi is a noun compound.

In Turkish, in many compounds, the second noun takes a compound ending, often the 3rd person possessive form:

• akım rölesi = current relay
• kaçak akım rölesi = leakage current relay

Then, when that whole compound becomes a definite direct object, Turkish adds the accusative:

• rölesi
  • -ni → rölesini

So rölesini contains both:

• the compound ending
• the accusative ending

Here de means also, too, or as well.

So:

• kaçak akım rölesini de içeriyor = it also includes the residual current relay

The de adds the idea that this is one more thing included.

A very important spelling point:

• this de is written separately
• it is not the same as the suffix -de meaning in/on/at

Because de usually comes right after the word or phrase it emphasizes.

Here:

• kaçak akım rölesini de = the residual current relay too / also the residual current relay

So the focus is on that object: the diagram includes that item as well.

If you moved de, the emphasis could change. For example:

• Tek hat şeması da kaçak akım rölesini içeriyor.
  = The single-line diagram also includes the residual current relay / The single-line diagram, too, includes ...

That version puts more focus on the subject.

içeriyor means contains or includes.

It comes from the verb içermek = to contain / include.

The -yor form is the Turkish present continuous, but in modern Turkish it is also very commonly used for:

• actions happening now
• general present statements
• descriptions in speech and writing

So here içeriyor is very natural, even though English might simply say includes.

You may also see içerir, which is more like a simple or formal general present:

• Tek hat şeması kaçak akım rölesini de içerir.

Both are possible, but içeriyor sounds very natural in everyday Turkish.

Because Turkish normally prefers Subject–Object–Verb word order.

So this sentence is:

• Tek hat şeması = subject
• kaçak akım rölesini de = object + also
• içeriyor = verb

This is a very typical Turkish sentence pattern.

Yes, it can be understood as definite from context.

Turkish does not use articles like a and the in the same way English does. Very often, whether something is a or the is understood from:

• context
• sentence structure
• whether the object has accusative marking

So Tek hat şeması can naturally mean:

• the single-line diagram
• or sometimes a single-line diagram

In this sentence, English will often use the.

Yes. Depending on the technical context, possible translations include:

• The single-line diagram also includes the residual current relay.
• The one-line diagram also includes the leakage current relay.
• The single-line schematic also includes the earth-leakage relay.

The exact English term may vary by industry, country, or document style, but the Turkish grammar stays the same.

A fairly literal breakdown would be:

• Tek hat şeması = single-line diagram
• kaçak akım rölesini de = the residual current relay also
• içeriyor = is including / includes

So the sentence is literally something like:

The single-line diagram also includes the residual current relay.

That is both a natural translation and a good grammatical match.