O comercializador de eletricidade anunciou a interrupção programada.

It refers to the company that sells electricity to customers — in other words, an electricity supplier or retailer.

In Portugal, comercializador is a fairly technical and official word. It does not literally mean a person in a shop or a marketer here; it is the company responsible for the commercial supply contract.

Portuguese often uses a noun + de + noun structure where English prefers a compound noun.

So:

• comercializador de eletricidade = electricity supplier
• literally: supplier of electricity

This is very common in Portuguese:

• fatura de eletricidade = electricity bill
• rede de transportes = transport network

Portuguese uses definite articles much more often than English.

• o comercializador = the supplier
• a interrupção = the interruption/outage

The articles also show grammatical gender:

• o for masculine singular
• a for feminine singular

Here:

• comercializador is masculine
• interrupção is feminine

Anunciou is the pretérito perfeito do indicativo, which usually corresponds to the English simple past:

• anunciar = to announce
• anunciou = announced

So the sentence states a completed past action: the supplier announced the scheduled interruption.

Because anunciou simply reports a completed event in the past.

Compare:

• anunciou = announced
• tem anunciado = has been announcing / has announced repeatedly or over a period, depending on context
• estava a anunciar = was announcing

In a neutral news-style sentence, anunciou is the most natural form.

It means a planned or scheduled interruption. In the context of electricity, it usually means a planned outage or scheduled power cut.

• interrupção = interruption
• programada = scheduled / planned

So this is not an unexpected blackout; it is one that was arranged in advance.

Because adjectives in Portuguese must agree with the noun they describe.

• interrupção is feminine singular
• so the adjective must also be feminine singular: programada

Compare:

• corte programado = scheduled cut-off
• interrupção programada = scheduled interruption

In Portuguese, adjectives often come after the noun, especially in neutral, factual language.

So:

• interrupção programada = scheduled interruption

Putting the adjective before the noun is sometimes possible in Portuguese, but it often sounds more literary, emphatic, or changes the nuance. In this kind of official statement, the normal order is noun + adjective.

It is a correct and fairly formal word, especially in official notices.

Depending on context, you may also see:

• corte de eletricidade = power cut
• falha de energia = power failure
• apagão = blackout, usually more dramatic or large-scale

Interrupção programada is especially common in formal utility-company language.

Because anunciar normally takes a direct object.

• anunciar algo = to announce something

So:

• anunciou a interrupção programada = announced the scheduled interruption

No extra preposition is needed before a interrupção.

Yes, eletricidade is the modern standard spelling.

You may also come across the older spelling electricidade, especially in older texts. But in current standard Portuguese, eletricidade is the usual form.

In European Portuguese, anunciou is roughly pronounced like ah-noon-see-OH, but with Portuguese sounds and reduced unstressed vowels.

A few useful points:

• ci here sounds like see
• the ending -ou is a diphthong, roughly like oh
• the stress falls on the last syllable: anunciou

As always, European Portuguese vowels are often more reduced than an English speaker expects.

Yes, and it would be understandable. Fornecedor de eletricidade means electricity provider/supplier.

However, comercializador de eletricidade is more specific and more typical in the Portuguese energy-sector context, especially in official or regulatory language.

So:

• fornecedor = more general
• comercializador = more technical/industry-specific

Yes. It sounds quite formal and official, like something from:

• a utility company notice
• a news report
• an administrative announcement

In everyday speech, people might say something simpler, such as:

• A empresa da eletricidade anunciou um corte programado.
• Vai haver uma interrupção de eletricidade programada.

The original sentence is correct, but definitely on the more formal side.