More detail is needed to answer this question. It depends on how it is being used. What hydrocarbon industry? Water, gasoline and sugar are all hydrocarbons.
Undervoltage relays are used to detect low voltage.
In my question, by writing hydrocarbon industry,what I meant was Oil Refinery or LNG processing plant etc. This question was asked to one of my friends in an interview.
The basic function of an undervoltage relay (27 device) is to detect undervoltage. The question then becomes what equipment do you need to protect from a UV condition. This could range from large motors (most small motors will stop because the motor contactor will not hold in past a certain voltage on decline) to a undervoltage load shedding scheme.
