Incorrect spelling, explanation: this is tricky, as the [ə] sound in pronunciation can be represented by both a and e in writing. Still, seperator is an incorrect word, because the base word here is separate, from the Latin separare. There is no reason why the English borrowing would change vowels in this kind of manner, so separator is the only correct version.

Correct spelling, explanation: separator is a word created out of a verb separate and a noun suffix -or. The word separate itself, however, comes from Latin separare, dictating the spelling, so there is not much room to change the spelling, as words of Latin origin tend to stay rather similar to their old, original forms.

Definition of separator:
Noun
1. A thing, often a machine, that separates (disconnects) two or more components of something
At the back of the facility, there is a huge oil-water separator.
When sending an e-mail to multiple recipients use commas as separators between their addresses.

Incorrect spelling

Incorrect spelling

Incorrect spelling