feszültségekbl
The term "feszültségekbl" appears to be a misspelling or a non-standard transliteration, likely from Hungarian. In Hungarian, "feszültség" translates to "voltage" or "tension." The suffix "bl" is not a standard grammatical element in Hungarian that would modify this word in a way that is commonly understood.
If "feszültségekbl" is intended to be a plural form with a case ending, "feszültségekből" would be the
Alternatively, it could be a typographical error where the intended word was simply "feszültség" (voltage/tension) or